Proxy Statement - Form DEF 14A

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF

PROXY MATERIALS FOR THE ANNUAL MEETING

TO BE HELD ON JUNE 13, 2024:

The Notice of Annual Meeting, this Proxy Statement and

the Company's 2023 Annual Report are available at www.proxyvote.com.

TABLE OF CONTENTS

ITEM 1 - ELECTION OF DIRECTORS

On the recommendation of the Nominating, Governance and Social Responsibility Committee ("Governance Committee"), our Board has nominated the seven persons listed below for election at the Annual Meeting. All nominees are current directors of the Company. Mr. Templin will continue as Chair of the Board subject to his reelection as a director at the Annual Meeting. Current Board member James C. Melville, who joined the Board in 2012, will be ending his Board service effective as of the conclusion of the Annual Meeting. During his time on the Board, Mr. Melville served on several committees of the Board and made valuable contributions to shaping the Company's strategic priorities that have led to value creation for shareholders. The Board thanks him for his service. Effective as of the conclusion of the Annual Meeting, the size of the Board will be reduced from eight members to seven members.

All nominees, with the exception of our President and Chief Executive Officer ("CEO"), Victor D. Grizzle, have been determined by the Board to be independent under the guidelines of the listing standards of the New York Stock Exchange ("NYSE") and our Corporate Governance Principles. Each nominee's term would, if elected, run from the date of such nominee's election until the election at our next annual meeting of shareholders and qualification of such individual's successor, or until earlier disqualification, resignation, removal, death or incapacity. We have no reason to believe that any of the nominees will be unwilling or unable to serve if elected.

The Governance Committee believes that aligning director qualifications, experience and skill sets with our business, strategy, risks and opportunities in

addition to the functional responsibilities of the Board is necessary to maintaining a Board of Directors that remains capable of effectively performing its oversight and decision-making responsibilities on behalf of the Company and its shareholders in a dynamic environment. As part of its annual Board evaluation process, the Governance Committee solicits the view of the entire Board regarding Board composition and factors the responses received into its Board succession planning and refreshment process.

Our Board does not have term limits or a mandatory retirement age. The Board believes that instituting fixed limits on the tenure of directors could deprive the Company of important experience and knowledge. While Board refreshment is an important consideration in the assessment of the Board's composition, the Board believes that the interests of the Company are best served by being able to take advantage of all available talent, and that the Board should not make determinations with regard to its membership solely on the basis of age and tenure. Performance concerns or changes in the skill sets or experience appropriate to meet the needs of the Company, the Board and its committees are addressed directly through the Board's evaluation, succession planning and refreshment processes.

Our Board believes that a board of directors composed of individuals with diverse attributes and backgrounds enhances the quality of our Board's deliberations and decisions. Our Board has an expansive view of diversity, going beyond the traditional concepts of race, gender and national origin, and we seek to ensure that our Board is composed of directors with diverse viewpoints, educational backgrounds and professional experience and expertise. Our Board

ITEM 1 - ELECTION OF DIRECTORS (CONTINUED)

recognizes that this diversity, coupled with strong personal and professional ethics, integrity and values, results in a board of directors that is well-qualified to guide the Company with good business judgment.

The Governance Committee expects each of the Company's directors to have proven leadership qualities, sound judgment, integrity and a commitment to the success of the Company. In evaluating director candidates and considering incumbent directors for

nomination to the Board, the Governance Committee evaluates a variety of factors. These include each nominee's independence, financial literacy, personal and professional accomplishments, and experience in light of the needs of the Company. For incumbent directors, the factors also include past performance on our Board and contributions to their respective committees. Our Board is also particularly interested in maintaining a mix of skills and qualifications that include the following:

OUR BOARD RECOMMENDS THAT YOU VOTE FORTHE ELECTION OF THE FOLLOWING NOMINEES:

ITEM 1 - ELECTION OF DIRECTORS (CONTINUED)

Mr. Grizzle was appointed as our President and Chief Executive Officer in March 2016. Previously, Mr. Grizzle served as Executive Vice President and Chief Executive Officer of Armstrong Building Products, a business unit of Armstrong, since January 2011. Prior to joining Armstrong, Mr. Grizzle served as Group President of Global Engineered Support Structures Coatings & Tubing and President of International Division for Omaha at Valmont Industries, Inc., an infrastructure and agricultural equipment manufacturer, since January 2006. Prior to Valmont, he served as President of the Commercial Power Division of EaglePicher Corporation, a manufacturing and resource extractive company. Before that, Mr. Grizzle spent 16 years at General Electric Corporation, where he served as an American business leader for General Electric's Silicones Division. Mr. Grizzle also serves on the board of directors of Franklin Electric, a global leader in the production and marketing of systems and components for water and automotive fuels. As President and Chief Executive Officer of AWI, Mr. Grizzle provides our Board with significant insight regarding our operations, strategic planning and operational design. In addition, Mr. Grizzle brings to our Board broad leadership and business expertise, as well as comprehensive experience in global operations and manufacturing matters.

Mr. Holder is currently the Chief Executive Officer of Loparex, Inc., a leading supplier of engineered release liner solutions. With a strong focus on material science expertise and industry-leading technology, Loparex, Inc. enables sustainable performance for customers worldwide. Prior to his role at Loparex, Inc., Mr. Holder served as the President and CEO of HZO, Inc., a provider of thin-film nanocoatings for electronics. Before that, he held the position of President and CEO at NN, Inc., a publicly-traded diversified industrial manufacturing company, from June 2013 to September 2019. Mr. Holder's professional journey also includes significant leadership roles at Eaton Corporation, where he served for over a decade. His experience extends to the aerospace industry, and he is a veteran of the U.S. Marine Corps. In addition to his current position, Mr. Holder serves on the board of Enerpac Tool Group Corp., a publicly-traded industrial tools and services company, where he is a member of the Audit Committee. He also holds positions on several private company boards. With extensive operating experience, senior executive leadership, and a background in manufacturing, Mr. Holder brings valuable insights to our Board. His expertise as a former public company CEO further enhances his contributions to our organization.

ITEM 1 - ELECTION OF DIRECTORS (CONTINUED)

Ms. Loughran served as a partner with PricewaterhouseCoopers LLP (PwC) from 1998 until her retirement in June 2018. Ms. Loughran has held various positions at PwC, including serving in its National Office from 2016 to 2018 and from 2000 to 2003, as Industrial Products Business Unit Leader of PwC's New York Metro market from 2013 to 2015, and as Retail & Consumer Business Development Leader of PwC's New York Metro market from 2010 to 2012. As a client service partner, Ms. Loughran led the global relationship and audit of numerous large, publicly-traded companies across a broad range of industries, and led the National Office effort on leveraging new and innovative technologies. Ms. Loughran also serves on the board of directors of Jacobs Solutions Inc., a publicly-traded engineering company, where she serves as chair of the Audit Committee and as a member of the ESG and Risk Committee. Ms. Loughran brings to our Board an extensive public accounting background, international experience, financial and capital markets expertise, and experience in mergers and acquisitions, risk management, and financial oversight and reporting.

Mr. Osborne served as Senior Vice President of Total Quality and Operations for Boeing Defense, Space & Security, one of The Boeing Company's three business units from May 2020 until October 2022. He was part of Boeing's Executive Council and became the chair of Boeing's Manufacturing Operations Council. Boeing is the world's largest aerospace company and leading manufacturer of commercial jetliners and defense systems. In his role, Mr. Osborne maintained oversight for Environment, Health & Safety and was responsible for Boeing's factory operations. Previously, he was Boeing's Senior Vice President, Enterprise Operations from May 2018 until April 2020. Before joining Boeing, Mr. Osborne served as Senior Vice President of Global Manufacturing and Quality at Navistar International Corporation, a holding company whose subsidiaries and affiliates produce International^® brand commercial and military trucks, from August 2013 to May 2018. He was also Senior Vice President of Custom Products at Navistar from May 2011 to August 2013. Before joining Navistar, he served as President and Chief Executive Officer of Federal Signal Corporation, a designer and manufacturer of a suite of products and integrated solutions for municipal, governmental, industrial and airport customers, from September 2008 to October 2010. Mr. Osborne began his career at Ford Motor Company. He currently serves on the board of directors of Quaker Houghton, a publicly traded global manufacturer of industrial process fluids and on the board of directors of Invitae Corporation, a publicly traded firm specializing in genetic testing. Mr. Osborne brings to our Board deep manufacturing, quality control, and executive leadership proficiencies, combined with valuable experience from his time as a public company chief executive officer and board member.

ITEM 1 - ELECTION OF DIRECTORS (CONTINUED)

Mr. Shurts served as the Executive Vice President and Chief Technology Officer at Sysco Corporation, a publicly-traded global leader in food service distribution, from 2012 until February 2019. Prior to this, Mr. Shurts served as Executive Vice President and Chief Information Officer at SUPERVALU, a publicly traded U.S. grocery retailer and wholesaler, from 2010 to 2012, and Chief Information Officer at Cadbury PLC, a British multinational confectionary company, from 2008 to 2010. Prior to this, Mr. Shurts has held various roles at Nabisco, including in finance, sales, supply chain, marketing, and technology. Mr. Shurts served on the board of directors of Con-Way Incorporated in 2015 until its acquisition by XPO Logistics Inc., where he served as a technology expert and a member of its Audit Committee and Nominating and Governance Committee. Mr. Shurts also serves on the board of directors of Stater Bros. Markets, a privately held grocery retailer, where he serves on the audit committee. Mr. Shurts brings to our Board extensive technology experience as a former Chief Information Officer, and in applying technology to improve and successfully transform business processes.

Mr. Templin served as Chair of the Board of Directors of Con-Way Incorporated, a multinational freight transportation and logistics company, from January 2014 until its acquisition by XPO Logistics Inc. in 2015. He previously served as Executive Vice President and Chief Financial Officer of Whirlpool Corporation, a multinational manufacturer and marketer of home appliances, from 2004 to 2012, and as Vice President and Controller of Whirlpool Corporation from 2003 to 2004. Prior, he served as Vice President, Finance and Chief Accounting Officer of Kimball International, Inc. He also previously served on the Board of Trustees of the Goldman Sachs Mutual Funds from 2013 to 2022. Mr. Templin brings to our Board extensive experience as a senior executive, public company board member and executive of manufacturing industries, as well as experience in risk management, strategic planning, finance, and mergers and acquisitions.

ITEM 1 - ELECTION OF DIRECTORS (CONTINUED)

Ms. Thomas is the Chief Strategy Officer and Vice President of Ardmore Roderick, a Chicago-based provider of civil engineering and construction management services and, prior to The Roderick Group's merger with Ardmore Associates, LLC, previously served as President and Chief Executive Officer of Ardmore Associates, LLC, where she was responsible for all financial, operational and management activities since 2003. Prior to founding Ardmore Associates, LLC, Ms. Thomas served as chair of the board of the United States Railroad Retirement Board from 1998 until 2003, and as Commissioner of the Chicago Department of Buildings of the city of Chicago from 1989 until 1994. During her tenure as Buildings Commissioner, the Department updated the building codes regarding the use of building materials for new construction and renovation projects. Ms. Thomas also serves on the board of directors of Wintrust Bank, a banking corporation, where she is a member of their credit and audit committees and on the board of directors of Spraying Systems Co., a privately held manufacturer of industrial spray nozzles, where she serves on the audit committee. Ms. Thomas serves on the boards of numerous local and civic organizations and foundations, including the Lyric Opera of Chicago (since 2007), the Chicago Zoological Society (since 2000), the Polk Bros Foundation (since 2009), the Brach Foundation (since 2015) and the Big Shoulders Foundation (since 2013). Ms. Thomas brings to our Board significant senior executive leadership experience, as well as relevant experience in manufacturing, construction, distribution and risk management.

ITEM 1 - ELECTION OF DIRECTORS (CONTINUED)

ITEM 1 - ELECTION OF DIRECTORS (CONTINUED)

CORPORATE GOVERNANCE

CORPORATE GOVERNANCE PRINCIPLES AND OTHER CORPORATE GOVERNANCE DOCUMENTS

Our Corporate Governance Principles include guidelines regarding the responsibilities, duties, service and qualifications of our Board, the determination of a director's independence and any conflict of interests, Board access to management and independent advisors, director compensation and stock ownership requirements, Board committees and other matters relating to corporate governance. Our Corporate Governance Principles are available on our website under "About Us" and then "Governance" or at https://investors.armstrongworldindustries.com/governance/governance-documents/default.aspx. Also available on our website under "About Us" and then "Governance" are the charters of the Audit Committee, the Finance Committee, the Management Development and Compensation Committee ("Compensation Committee"), and the Governance Committee of the Board, along with the Armstrong Code of Business Conduct and the Armstrong Code of Ethics for Financial Professionals. Our website is not part of this proxy statement and references to our website address in this proxy statement are intended to be inactive textual references only.

DIRECTOR INDEPENDENCE

It is the policy of the Company that our Board consist of a majority of directors who are not employees and are independent under all applicable legal and regulatory requirements, including the independence requirements of the NYSE and the U.S. Securities and Exchange Commission (the "SEC"). For purposes of evaluating the independence of directors, in accordance with our Corporate Governance Principles, our Board will consider all relevant facts and circumstances from the standpoint of the director, and also from that of persons or organizations with which the director has affiliations. Consistent with our Corporate Governance Principles, to be considered "independent," a director must meet qualifications established by the Governance Committee to assist in the determination, which qualifications either meet or exceed the independence requirements of the NYSE and the SEC. Each of our standing Board committees must be composed entirely of independent directors and comply with all applicable rules and requirements of the NYSE and the SEC.

Our Board has determined that all of our director nominees, with the exception of Mr. Grizzle, our President and CEO, are independent under NYSE listing standards and our Corporate Governance Principles. In addition, our Board has further determined that each of the members of the Audit Committee, the Compensation Committee, the Finance Committee and the Governance Committee are independent within the meaning of the NYSE listing standards, any applicable minimum standards required by the Securities Exchange Act of 1934, as amended (the "Exchange Act"), and enhanced standards required for membership on such committees by our Bylaws, namely that directors serving on such committees meet the independence criteria under both NYSE rules and Rule 10A-3(b)(1)under the Exchange Act.

BOARD'S ROLE IN RISK MANAGEMENT OVERSIGHT

Our Board oversees the Company's management processes for assessing and managing risk, both as a full Board and through its committees, which meet regularly and report to the full Board. Management is charged with managing risk through robust internal policies and controls.

Enterprise Risk Management The Company actively maintains an enterprise risk management program. Risk management is an integral part of the Company's culture. Management's role is to identify, mitigate, guide and review the efforts of our business units, consider whether the residual risks are acceptable, and approve plans to deal with serious risks. Our Board's role in risk management is to review the performance and functioning of the Company's overall risk management efforts and management's establishment of appropriate systems for managing risk. Specifically, our Board reviews our:

CORPORATE GOVERNANCE (CONTINUED)

Pursuant to its charter, the Audit Committee has primary oversight responsibility with respect to the design of our enterprise risk management program, including for periodically reviewing the process, methodology, and tools used by management to identify, evaluate, organize, assess and mitigate significant risks.

Management regularly provides input and feedback on business segment risks during periodic business reviews and annual strategic planning discussions. Senior management regularly meets with designated individuals responsible for mitigating risks to review and assess risk mitigation and control measures. In addition, senior management regularly reevaluates the appropriateness of risk assessments and priorities. This process includes identifying risks that could prevent achievement of business goals and strategic plans. Our internal audit team uses the resulting information as a basis for developing its annual audit plan.

Cybersecurity RiskOur Board has responsibility for oversight of management's cybersecurity risk program and receives regular updates from our Chief Information Officer. The updates, provided on a semi-annual basis, cover a range of topics, including the performance of our cybersecurity program against established goals and external standards, insights into the evolving cybersecurity landscape, current events and recent cybersecurity threats, and progress in enhancing the Company's cybersecurity posture. Additional information about the Company's cybersecurity risk program is available in Item 1C of the Company's Annual Report on Form 10-Kfiled with the SEC on February 20, 2024.

Responsibilities of our Board and its CommitteesIn addition to audit and assurance reports provided by our internal audit team, our Board periodically reviews summary reports from senior management that assess the strategic, operational, infrastructure and external risks facing the Company. These reports generally utilize our Enterprise Risk Management framework to identify the likelihood and impact of such risks and identify appropriate mitigation strategies and efforts. Each Board committee, consistent with its charter,

reviews and evaluates risks associated with their respective areas of oversight responsibility, reports on those oversight activities to our Board, and assists our Board in its ongoing monitoring and review of those risks, including as described in "BOARD MEETINGS AND COMMITTEES" below.

BOARD OVERSIGHT OVER SUSTAINABILITY MATTERS

Pursuant to its charter, our Governance Committee is responsible for oversight of our corporate social responsibility program and practices, including its priorities, objectives, strategy and performance, and periodic sustainability reporting and disclosures. The Governance Committee receives updates from management on our sustainability program at least quarterly. Other Board committees assist the Governance Committee in fulfilling this responsibility by overseeing related risks in their areas of responsibility, including:

BOARD'S ROLE IN STRATEGIC PLANNING

Our Board oversees and advises on the Company's overall strategy and annually reviews the strategic priorities and initiatives of each business segment. In evaluating significant investments or capital allocation decisions, the Board generally considers the Company's strategic plan and the potential impact on long-term shareholder value creation.

BOARD'S ROLE IN SUCCESSION PLANNING

Our Board is actively engaged and involved in talent management. Our Board reviews the Company's "Organization Vitality" initiatives in support of its business strategy at least annually. This includes a detailed discussion of the Company's leadership bench and succession plans with a focus on key positions at the senior officer level, including CEO. During 2023, our Board and the Compensation Committee met in furtherance of these initiatives. In addition, each committee of the Board regularly discusses the talent pipeline for specific critical roles. High potential leaders are given exposure and visibility to Board members

CORPORATE GOVERNANCE (CONTINUED)

through formal presentations and informal events. More broadly, our Compensation Committee and our Board are regularly updated on key talent indicators for the overall workforce, including diversity, recruiting and development programs.

BOARD LEADERSHIP STRUCTURE

Our Bylaws and Corporate Governance Principles provide our Board with the flexibility to determine what leadership structure works best for us, including whether the same individual should serve as both Chair of the Board and CEO. Since 2010, our Board has determined to split the positions of Chair of the Board and CEO. The split of these positions allows Mr. Grizzle, our President and CEO, to focus on managing the business, while Mr. Templin, as Chair of the Board, oversees our Board's functions. Our Board will continue to evaluate its leadership and governance structure within the context of the specific needs of the business, current Board composition, and the best interests of the Company and our shareholders.

Responsibilities of the Chair of the Board include recruiting new Board members, overseeing the evaluation and compensation of the CEO, ensuring an appropriate succession plan, overseeing independent evaluation of risk, coordinating Board meeting schedules and agenda, chairing and leading the discussions at the Board meetings, and assisting with the annual performance evaluations of the Board, its committees and its individual members coordinated by the Governance Committee. The Chair ensures that information provided by management to the Board is sufficient for the Board to fulfill its duties and communicates with other directors on key issues and concerns outside regularly scheduled meetings. The Chair is also responsible to ensure the effective functioning of Board committees through appropriate delegation to, and membership of, the committees. Finally, the Chair of the Board facilitates the independent oversight required by our Bylaws and Corporate Governance Principles, including by ensuring that the Board meets at regularly scheduled executive sessions, outside the presence of management. Our Chair presides at these sessions. In addition, each of the Board's four standing committees regularly meet at similar executive sessions, at which the respective committee chairs preside.

COMMUNICATION WITH THE BOARD

Any person who wishes to communicate with the Board, nonemployee directors as a group, or individual directors, including the Chair of the Board, may direct a written communication to the attention of the Corporate Secretary at the Company's corporate offices at 2500 Columbia Avenue, Lancaster, Pennsylvania 17603. The Corporate Secretary will forward these communications to the intended recipient director(s), as appropriate, depending on the facts and circumstances outlined in the communication. Any person may also send general messages to directors by email to [email protected]. An individual wishing to send an email message to the Governance Committee, including a recommendation regarding a prospective director, may send the message to [email protected]. The Corporate Secretary will forward these messages, as appropriate.

SHAREHOLDER OUTREACH

The Company's relationships with its shareholders and other stakeholders are a critical part of our corporate governance profile, and the Board recognizes the value of taking their views into account. Among other things, this engagement helps the Board and management understand the larger context and impact of the Company's operations, learn about expectations for our performance, assess emerging issues that may affect our business or other aspects of our operations, and shape policy.

We maintain a formal shareholder outreach program to obtain investor perspectives on key topics of interest, such as corporate governance, executive compensation, sustainability and other matters. On an annual basis, we intend to continue to solicit feedback from institutional investors, including asset managers, pension funds and social responsibility investors.

Shareholder communications and inquiries are shared with Company management, and with the Chair of the Board and the Board Committees, as appropriate. In 2023, members of Company management engaged in discussions with shareholders to discuss topics relating to sustainability, executive compensation and other matters.

CORPORATE GOVERNANCE (CONTINUED)

BOARD MEETINGS AND COMMITTEES

The Board met six times during 2023, one of which was a special meeting.

There are four standing committees of the Board: the Audit Committee, the Compensation Committee, the Finance Committee and the Governance Committee, as described below.

Consistent with our Corporate Governance Principles, each standing committee has a charter and consists solely of "independent" or "outside" directors who meet applicable independence standards required by the NYSE, the SEC, and our Bylaws. Each committee reports to the Board regularly and evaluates the effectiveness of its performance annually. The membership of each committee is determined by the Board on the recommendation of the Governance Committee. The Company's Corporate Governance Principles provide that (i) directors who are currently fully employed should not serve on more than two other public company boards, and (ii) other directors should not serve on more than four other public company boards.

All director nominees who served on the Board during 2023 participated in over 75% of the meetings of the Board during their tenure and over 75% of the meetings of the Committees on which they served. Board members are expected to attend annual meetings in person or virtually, via the Internet. All Board members except one director attended the 2023 Annual Meeting.

AuditCommitteeThe Audit Committee met five times during 2023. The members of the Audit Committee are Barbara L. Loughran (Chair), Richard D. Holder, Wayne R. Shurts, and Roy W. Templin. Under its charter, the Audit Committee:

CORPORATE GOVERNANCE (CONTINUED)

Each member of the Audit Committee meets the NYSE and SEC financial literacy requirements. The Board has determined that each of Ms. Loughran and Mr. Templin qualifies as an "Audit Committee Financial Expert" as defined pursuant to the Exchange Act. The Audit Committee regularly meets independently with the Company's internal and independent auditors, with the leader of the Company's compliance function, and with various members of management in furtherance of its responsibilities.

Finance CommitteeThe Finance Committee met four times during 2023, two of which were special meetings. The members of the Finance Committee are Roy W. Templin (Chair), Richard D. Holder, Barbara L. Loughran, and James C. Melville. Under its charter, the Finance Committee:

Management Development and Compensation CommitteeThe Compensation Committee met seven times during 2023, two of which were special meetings. The members of the Compensation Committee are Wayne R. Shurts (Chair), James C. Melville, William H. Osborne, and Cherryl T. Thomas. Under its charter, the Compensation Committee:

Nominating, Governance and Social Responsibility CommitteeThe Governance Committee met five times during 2023. The members of the Governance Committee are Richard D. Holder (Chair), Barbara L. Loughran, William H. Osborne and Cherryl T. Thomas. Under its charter, the Governance Committee:

CORPORATE GOVERNANCE (CONTINUED)

Other CommitteesIn addition to the four standing committees described above, members of the Board may meet on an ad hoc basis to discuss, review and, as appropriate, approve matters through other committees established by the Board. These ad hoc committees report to the Board and may review subjects such as environmental matters, succession planning and crisis response.

COMPENSATION COMMITTEE INTERLOCKS AND INSIDER PARTICIPATION

None of the members of the Compensation Committee has ever been an officer or employee of

the Company or its subsidiaries, or had any relationship with the Company that requires disclosure under applicable SEC regulations.

REVIEW OF RELATED PERSON TRANSACTIONS

For the fiscal year ended December 31, 2023, one transaction with related persons, as defined in Item 404 of the SEC's Regulation S-K("Item 404") was approved. Alexander K. King, the son of Ms. Dawn Kirchner-King, was a Production Manager for the period January 1, 2023 through February 28, 2023 at Architectural Components Group, Inc., a wholly owned subsidiary of the Company, and thereafter a Project Manager with the Company. Ms. Dawn Kirchner-King was the Senior Vice President and Chief Information Officer of the Company until her resignation as of June 30, 2023. For the year ended December 31, 2023, Mr. King received a base salary of $135,000, a cash bonus of $7,550 as part of the Company's Annual Incentive Program, retirement contributions of $8,437, and a cash payment of $20,000 in lieu of relocation benefits. He also participates in the Company's other benefit programs on the same basis as other employees at the same level.

We have written policies pertaining to related person transactions. Any related person transaction that may arise is required to be reviewed and approved by the Governance Committee, who must have no connection with the transaction. Related person transactions would include transactions by the Company or any subsidiary with any director, director nominee, executive officer, shareholders owning more than 5% of the Company's outstanding common shares, per share par value $0.01 ("Common Stock"), or immediate family member of any of the foregoing, and transactions with businesses affiliated with any director or director nominee that meet the specifications in Item 404. The Chair of the Governance Committee has authority to approve transactions involving sums less than the disclosure threshold set in Item 404. The material details of any such matters are required to be disclosed to the Governance Committee at its next regular meeting.

POLICY ON MAJORITY VOTING IN THE ELECTION OF DIRECTORS

Our Board maintains a Policy on Majority Voting as one of our Corporate Governance Principles. The

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Policy provides that in an uncontested election of directors, any nominee who receives a greater number of votes "withheld" from the nominee's election than votes "for" the nominee's election will, within 10 business days following the certification of the shareholder vote, tender written resignation to the Board. Such tendered resignation will be considered by the Governance Committee taking into account any factors or other information it considers appropriate and relevant and, within 60 days following the date of the shareholders' meeting at which the election occurred, will make a recommendation to the Board concerning the acceptance or rejection of such resignation. The Board will take formal action on the Governance Committee's recommendation no later than 90 days following the date of the shareholders' meeting at which the election occurred. The Board will consider the information, factors and alternatives considered by the Governance Committee and such additional factors, information and alternatives as the Board deems relevant.

Following the Board's decision on the Governance Committee's recommendation, the Company, within four business days after such decision is made, will publicly disclose, in a current report on Form 8-Kfiled with the SEC, the Board's decision, and, if applicable, the Board's reasons for rejecting the tendered resignation. A director whose resignation is accepted by the Board may not be re-appointedto fill the vacancy created by such director's resignation.

No director who is required to tender such director's resignation shall participate in the Governance Committee's deliberations or recommendation, or in the Board's deliberations or determination, with respect to accepting or rejecting the resignation as a director. If a majority of the members of the Governance Committee are required to tender their

resignations, then the independent directors who are not required to tender their resignations will appoint an ad hoc Board committee from amongst themselves, consisting of such number of independent directors as they may determine to be appropriate, solely for the purpose of considering and making a recommendation to the Board with respect to the tendered resignations. If such ad hoc committee would have been created but fewer than three directors would be eligible to serve on it, then the entire Board (other than the director whose resignation is being considered) will make the determination to accept or reject the tendered resignation without any recommendation from the Committee and without the creation of an ad hoc committee.

SHAREHOLDER-RECOMMENDEDDIRECTOR CANDIDATES

The Governance Committee will consider director candidates nominated by shareholders. The procedures for recommending candidates are posted at https://investors.armstrongworldindustries.com/governance/contact-the-board/default.aspx.Shareholders who wish to suggest individuals for service on the Board are requested to review Article II, Section 4 of our Bylaws and supply the information required in (a) through (l) of that Section in a written request to the Corporate Secretary at the Company's corporate offices at 2500 Columbia Avenue, Lancaster, Pennsylvania 17603.

When evaluating the candidacy of nominees proposed by shareholders, the Governance Committee may request additional information as it may consider reasonable to determine the proposed nominee's qualifications to serve as a member of the Board.

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SUSTAINABILITY

Sustainability is an important part of our approach to doing business. We aim to continually improve the environmental sustainability of our products and operating processes, build a more diverse, equitable and inclusive workforce, and provide meaningful support for our communities.

Our sustainability program is organized around three functional "pillars": People, Planet and Product. Each pillar encompasses specific 2030 goals and key performance targets.

Our program pillars are focused on these key priorities and objectives:

Healthy and Circular ProductsWe intend to create products and solutions from healthy, sustainably sourced materials by eliminating chemicals of concern through sustainable supply chains. We aim to design our products to be recycled, reused or repurposed and drive circularity in our operations, with customers, and throughout our value chain. We aim to make a positive contribution to spaces and the environment by decreasing our products' carbon and water footprint, and by creating solutions that actively contribute to health and wellness.

Healthy PlanetWe intend to reduce our greenhouse gas emissions and increase our reliance on renewable energy using climate science-based targets that include, among other things, a reduction of Scope 1 and Scope 2 greenhouse gas (GHG) emissions by 30% from their respective 2019 baselines, which reduction is aligned with a well below 2-degreeCelsius scenario and has been verified by the Science Based Target initiative ("SBTi"). We aim to eliminate waste through innovative manufacturing processes and by creating circular systems from order to delivery.

Thriving People and CommunitiesWe intend to continue engaging in communities where we operate to contribute to the vibrant places to live and work by strengthening and supporting local programs and fostering impactful relationships. We aim to continue developing an inclusive culture and diverse workforce at all locations. We aim to continue to cultivate a culture that leads to safe, healthy, fulfilled employees.

2023 SUSTAINABILITY REPORT

In July 2023, we published our third Sustainability Report ("2023 Sustainability Report"), in which we discussed the progress made in 2022 towards our 2030 goals and targets for each of our pillars.

We prepared our 2023 Sustainability Report using the frameworks of the Sustainability Accounting Standards Board (SASB) Building Products & Furnishings standards, the Global Reporting Initiative (GRI), and the Task Force on Climate-Related Financial Disclosures (TCFD).

GOVERNANCE, CORPORATE LEADERSHIP AND MANAGEMENT

The Governance Committee has responsibility for overseeing our sustainability program and practices. The Audit Committee maintains responsibility for overseeing management's processes for validating data prior to management issuing material public disclosures related to the Company's sustainability program. Additional information regarding the Governance Committee's oversight responsibilities and the involvement of other Committees of the Board can be found in the "BOARD OVERSIGHT OVER SUSTAINABILITY MATTERS" Section on page 10.

Our sustainability program is led by a dedicated sustainability leader, Kelsey Herring, Director of Sustainability. Reporting to Austin K. So, Senior Vice President, General Counsel, Secretary and Chief Compliance Officer, Ms. Herring is responsible for designing and implementing action plans towards our enterprise-wide goals.

Our Sustainability Council, comprising senior leaders from various functions within the organization, is responsible for embedding and implementing our sustainability goals and initiatives throughout the organization.

In support of these goals and initiatives, cross-functional employee pillar teams - for each of the People, Planet and Product pillars - help assess our current state and develop action plans and interim targets to enable us to achieve those goals.

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THE ARMSTRONG WORLD INDUSTRIES FOUNDATION

We created the Armstrong World Industries Foundation as our philanthropic arm in 1985. Today, the Foundation's strategy is primarily focused on making a positive difference in the lives of people where they live, work, learn, heal and play, through awarding grants to qualified charitable organizations that meet at least two of the following criteria:

Today, the Foundation's mission is to support: (a) current and future employees and retirees through gift matching programs, hardship support, and emergency/disaster relief support; (b) communities in which we operate; and (c) the qualified charitable efforts of architects, designers, contractors and others in the building and construction community who are dedicated to elevating the importance of healthy and sustainable spaces for people's lives.

MORE INFORMATION

More information about our sustainability program and practices, including the 2023 Sustainability Report, is available in the "Sustainability" section of our website at https://armstrongceilings.com. Our website, 2023 Sustainability Report and other information available on our website are not part of, nor are they incorporated by reference into, this proxy statement and references to our website address in this proxy statement are intended to be inactive textual references only.

Our Sustainability goals, key performance indicators, projects, plans, targets and expectations are aspirational and forward-looking. Statements of aspiration, future events or conditions are sometimes identified by the words "will," "should," "intend," "expect," "estimate," "believe," "could," "project," "target" or other similar words or expressions. By their nature, they are based upon current plans, estimates and expectations that are subject to risks, uncertainties and assumptions. As such, no guarantees or assurances are made that they will be achieved or successfully executed. Additionally, the Sustainability data, statistics and metrics included herein, unless otherwise specifically indicated, are non-auditedestimates, were not prepared in accordance with U.S. generally accepted accounting principles ("GAAP"), have not been externally assured, continue to evolve and may be based on assumptions believed to be reasonable at the time of preparation, but should not be considered guarantees. Except to the extent required by applicable law, we undertake no obligation to publicly update or revise any forward-looking Sustainability statement, whether as a result of new information, future events or otherwise.

MANAGEMENT

COMPENSATION OF DIRECTORS

In establishing compensation for our nonemployee directors, including the overall value of compensation and the mix of cash and equity, the Board analyzes competitive market data and any underlying director compensation trends generally, and compares our program to those of similarly sized companies in comparable industries. The Board is compensated through a combination of cash and equity annual retainers. Nonemployee directors receive more than half of their annual retainer in equity in order to align their compensation with the interests of shareholders. Directors do not receive meeting fees or perquisites. The Board believes that this level of compensation supports the Company's ability to

attract directors with suitable backgrounds and experiences. A director who is an officer or employee of the Company or its subsidiaries is not compensated for service on the Board or on any committee of the Board.

On an annual basis, the Governance Committee reviews the compensation program for nonemployee directors, which program includes the 2016 Directors Stock Unit Plan, as amended (the "2016 Directors Stock Unit Plan"). The review includes an analysis of competitive market data and any underlying director compensation trends with assistance from an independent compensation consultant, as required.

COMPENSATION OF DIRECTORS (CONTINUED)

Annual grants for the equity portion of the retainer are effective as of the first business day following the date of the Annual Meeting, and the amount of

each grant is determined by the NYSE closing price of our shares of Common Stock on that date.

SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS, MANAGEMENT AND DIRECTORS

SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS, MANAGEMENT AND DIRECTORS (CONTINUED)

SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS, MANAGEMENT AND DIRECTORS (CONTINUED)

SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS, MANAGEMENT AND DIRECTORS (CONTINUED)

Stock Ownership Guidelines

In accordance with our Corporate Governance Principles, each nonemployee director must acquire as reasonably promptly as practicable following such director's appointment as a director (taking into account, among other things, the applicable director's individual financial and other circumstances and the then-current price of our securities) and then hold until six months following the end of such director's service, shares of Common Stock equal in value to three times the director's annual cash retainer fee at the time such director joined the Board. Once the share ownership requirement is reached by a

director, any later fluctuation in stock price is disregarded and no additional stock acquisition is required by such director. This requirement is waived as to directors designated by shareholders who, while not holding shares individually, nevertheless have an equity interest in Common Stock of the Company by virtue of being a designee of the shareholder. All of the current directors have achieved this ownership requirement. For further details regarding stock ownership by nonemployee directors, see page 24 of this proxy statement. As an officer of the Company, Mr. Grizzle is not subject to the stock ownership guidelines for nonemployee directors but is subject to separate stock ownership guidelines for executives.

ITEM 2 - RATIFICATION OF THE APPOINTMENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

The Audit Committee selected KPMG LLP to audit our consolidated financial statements and our internal control over financial reporting for 2024. In accordance with past practice, this selection will be presented to the shareholders for ratification at the Annual Meeting; however, consistent with the requirements of the Sarbanes-Oxley Act of 2002, the Audit Committee has ultimate authority in respect of the selection of our independent

registered public accounting firm. The Audit Committee may reconsider its selection if the appointment is not ratified by the shareholders.

A representative of KPMG LLP will be in attendance at the Annual Meeting to respond to appropriate questions and will be afforded the opportunity to make a statement at the meeting, if he or she desires to do so.

THE BOARD OF DIRECTORS RECOMMENDS THAT SHAREHOLDERS VOTE FORTHE RATIFICATION OF THE APPOINTMENT OF KPMG LLP.

AUDIT COMMITTEE REPORT

FEES PAID TO INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

FEES PAID TO INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM (CONTINUED)

ITEM 3 - ADVISORY APPROVAL OF EXECUTIVE COMPENSATION

The Company is seeking your advisory vote on our executive compensation program. The Company asks that you support the compensation of our named executive officers as disclosed in the Compensation Discussion and Analysis section and the accompanying tables contained in this proxy statement. Because your vote is advisory, it will not be binding on the Board or the Company. However, the Board will review the voting results and take them into consideration when making future decisions regarding executive compensation. This item, which is provided pursuant to Section 14A of the Exchange Act, is commonly referred to as a "say-on-pay"resolution.

The Company has in the past sought approval from shareholders regarding the incentive plans that we use to motivate, retain, and reward our executives. Those incentive plans, including the 2016 Long-Term Incentive Plan and the Equity and Cash Incentive Plan adopted in 2022, make up a majority of the pay that the Company provides to our executives. Over the years, the Company has made a number of changes to its disclosures concerning executive compensation, as well as to its executive compensation programs, in response to shareholder input, including a number of enhancements mentioned in this proxy statement.

Our executive compensation program has played a material role in our ability to drive strong financial results and attract and retain a highly experienced, successful team to manage our company.

We believe that our executive compensation program is structured appropriately to support our company and our business objectives.

Our Compensation Committee has developed and maintained a compensation program that is intended to: align executive interests with shareholders' interests; link pay and performance by placing a significant portion of compensation "at risk" based on performance against pre-establishedgoals; and provide a competitive level of compensation globally to enable access to high-quality executives in a competitive way.

As reflected in the total shareholder return components of our new program, if the value we deliver to our shareholders increases, so does the compensation we deliver to our executives.

We maintain strong corporate governance over our executive pay programs. We closely monitor the compensation programs and pay levels of executives from companies of similar size and complexity, so that we may ensure that our compensation programs are within the norm of a range of market practices.

Our Compensation Committee, our Chief Executive Officer, and our head of Human Resources engage in a talent review process annually to address succession and executive development for our CEO and other key executives.

THE BOARD OF DIRECTORS RECOMMENDS THAT SHAREHOLDERS VOTE FORTHE COMPANY'S COMPENSATION OF OUR NAMED EXECUTIVE OFFICERS AS DISCLOSED IN THE COMPENSATION DISCUSSION AND ANALYSIS SECTION AND THE ACCOMPANYING COMPENSATION TABLES CONTAINED IN THIS PROXY STATEMENT.

COMPENSATION DISCUSSION AND ANALYSIS

Victor D. GrizzlePresident and CEO

Christopher P. CalzarettaSenior Vice President and CFO

Mark A. HersheySenior Vice President, Americas

Austin K. SoSenior Vice President, General Counsel, Secretary and Chief Compliance Officer

Monica MaheshwariSenior Vice President, Human Resources⁽¹⁾

COMPENSATION DISCUSSION AND ANALYSIS (CONTINUED)

Please also see our Consolidated Financial Statements in our Annual Report on Form 10-Kfiled with the SEC on February 20, 2024.

2023 Compensation Plan Design

Our Compensation Committee reviews our compensation plans at least annually and, in 2023,

determined to continue and maintain the Annual Incentive Plan design established in recent years but made some changes to our Long-Term Incentive Program. Our plans are designed to work together to directly link compensation opportunities to meaningful achievements in Company strategy and performance and long term stock price performance.

COMPENSATION DISCUSSION AND ANALYSIS (CONTINUED)

Shareholder Engagement

In 2023, we continued to engage with our shareholders to seek their perspectives on corporate governance, our executive compensation program, sustainability and other matters. We conducted formal outreach over the course of the year with shareholders representing approximately 25% of our outstanding shares at the time of outreach. These discussions were conducted by Austin So, our Senior Vice President, General Counsel, Secretary and Chief Compliance officer, and Monica Maheshwari, our Senior Vice President, Human Resources, as well as other subject matter experts within the Company. These discussions were complemented by our ongoing outreach initiatives led by our Investor Relations team. Detailed summaries of these discussions were shared with the Compensation Committee and our Nominating, Governance and Social Responsibility Committee, which considers and incorporates shareholder feedback in our governance processes. Noteworthy topics from our outreach discussions in 2023 included discussions on talent acquisition and retention considering current labor market challenges and incremental investment required for meeting our 2030 sustainability targets. We consistently received positive feedback on our sustainability disclosure program. Our 2023 nonbinding shareholder advisory vote on executive

compensation approval vote of 95% reflects strong shareholder support for the design and outcomes of our executive compensation programs. Shareholder communications and inquiries are shared with Company management and with the Chairs of the Board and its Committees, as appropriate. The Company considers shareholder feedback as it shapes its governance and executive compensation programs and policies and disclosures. Past examples of disclosure added after communications with shareholders includes a Board skill matrix, enhanced disclosure on Board diversity and additional information on environmental and social initiatives.

Our Executive Compensation Philosophy, Objectives, Elements and Characteristics

Compensation Philosophy and Objectives

Our long-term success and growth depend on highly capable leaders with appropriate experience and skills to deliver our strategy in a variable and challenging market environment. Our executive compensation program is designed to attract, motivate and retain those leaders. In developing and maintaining this program, our Compensation Committee focuses on the following key objectives:

COMPENSATION DISCUSSION AND ANALYSIS (CONTINUED)

COMPENSATION DISCUSSION AND ANALYSIS (CONTINUED)

Compensation Characteristics

At the direction of our Compensation Committee, we subscribe to a "pay-for-performance"philosophy. Our compensation program maintains the following attributes:

COMPENSATION DISCUSSION AND ANALYSIS (CONTINUED)

Our Compensation Committee is responsible for executive compensation program design and the decision-making process relative to NEOs specifically, and broadly, as these programs apply to other senior leaders and participating employees. The Compensation Committee solicits input from

the independent members of the Board, our CEO, other members of management and its independent compensation consultant to assist with its responsibilities. The following summarizes the roles of each of the key participants in the executive compensation decision-making process.

COMPENSATION DISCUSSION AND ANALYSIS (CONTINUED)

Independent Compensation Consultant

After partnering with Willis Towers Watson for the past ten years as its independent consultant, in July 2023 the Compensation Committee terminated this relationship and engaged Meridian Compensation Partners, LLC ("Meridian") as its independent compensation consultant ("Compensation Consultant") on executive compensation matters.

Willis Towers Watson performed the following services relating to 2023 compensation decisions:

The Compensation Committee determined the work of Willis Towers Watson and Meridian did not raise any conflicts of interest in 2023. In making this assessment, the Compensation Committee considered the independence factors enumerated in Rule 10C-1(b)under the Exchange Act and corresponding rules of NYSE. After considering all of the factors provided in the SEC and the NYSE rules and all other factors relevant to Willis Towers Watson's or Meridian's independence, the Compensation Committee has determined both were independent.

Use of Competitive Data

In setting NEO compensation, the Compensation Committee considers independent survey data, peer compensation data, tally sheets, wealth accumulation analyses and related benchmark information.

Annual Compensation Benchmarking

Annually, the Compensation Committee reviews all components of NEO compensation compared to the Competitive Market (defined below) data.

In general, we target NEO pay to be at or near the 50th percentile of our defined Competitive Market, but we may deviate from this target based on an individual's performance, internal equity with peers situated at similar levels, or to attract the required level of business knowledge and leadership needed to achieve our strategic objectives.

The principal sources of market data include the following ("Competitive Market"):

Consideration of 2023 Advisory Shareholder Vote on Executive Compensation

At our 2023 Annual Meeting, our shareholders expressed a preference that advisory votes on executive compensation occur every year. Accordingly, the Board is continuing the practice of an annual advisory vote on executive compensation until the next required vote on the frequency of shareholder votes on the compensation of executives. The next vote concerning the frequency of the advisory vote on executive compensation is scheduled to occur at the 2029 annual meeting of shareholders.

Our Board and Compensation Committee appreciate and value the views of our shareholders regarding our executive compensation program.

The strongly favorable (95%) results of the 2023 advisory vote on executive compensation, provided further support to the Compensation Committee that our executive compensation programs have been effective in implementing our stated compensation philosophy and objectives in a manner consistent with shareholder preference.

The Compensation Committee recognizes executive pay practices and notions of sound governance principles continue to evolve. While no specific changes were implemented as a result of the 2023 advisory vote, the Compensation Committee intends to continue monitoring trends and invites our shareholders to communicate any concerns or opinions on executive pay directly to the Compensation Committee or the Board. Please refer to "COMMUNICATION WITH THE BOARD" on page 11 for further information about communication with the Compensation Committee or the Board.

COMPENSATION DISCUSSION AND ANALYSIS (CONTINUED)

Tally Sheets and Wealth Accumulation Analyses

The Compensation Committee uses tally sheets and wealth accumulation analyses when evaluating compensation-related decisions for each NEO.

Compensation Mix

To facilitate the link between NEO pay and Company performance, a significant amount of TDC is performance-based and "at risk."

In 2023, 86% of our CEO's target TDC, and 64% of the average target TDC of our other NEOs, was variable and "at risk." The following chart shows the 2023 compensation mix, consisting of base salary, AIP, and RSUs/PSUs as the LTIP grants.

2023 COMPENSATION DESIGN AND OUTCOMES

Base Salary

In 2023, the Compensation Committee reviewed the base salaries of our NEOs. After consideration of individual performance and the competitiveness of each NEO's base salary compared to the Competitive Market, the Compensation Committee increased base salaries for each of our NEOs. Pay increases were approved during the Compensation Committee meeting held in February 2023 effective April 1, 2023.

COMPENSATION DISCUSSION AND ANALYSIS (CONTINUED)

The table below represents each NEO's base salary as of December 31, 2023. This information differs from the Summary Compensation Table ("SCT"), which reflects the total base salary received for the year.

Annual Incentive Plan Awards

AIP awards provide an annual incentive opportunity for achieving financial results based on short-term performance goals tied to the Company's annual operating plan.

Each NEO's target AIP opportunity (expressed as a percent of base salary) is based on the NEO's role, responsibility and alignment with similar internal positions and the external Competitive Market. Actual payout varies based upon actual business performance relative to performance targets, and may be subject to individual performance modifiers against pre-establishedindividual goals, including, performance related to sustainability initiatives.

For 2023, AIP awards were determined based on the following formula, measures and weightings all subject to the approval of our Compensation Committee.

2023 Target AIP Opportunity

2023 target AIP opportunities for NEOs are set forth in the table below. With the exception of Mr. Grizzle, there were no changes to these target percentages from 2022.

2023 AIP Performance Metrics

Our Compensation Committee selected revenue and adjusted EBITDA as performance metrics in order to create strong alignment with shareholders and reflect key measures of value creation. Revenue was weighted 30% and adjusted EBITDA was weighted 70%.

These performance metrics align to key elements of our operating plan and financial goals, including revenue growth, manufacturing productivity, optimization of invested capital and competitive SG&A levels, and they are strong indicators of our overall operating performance.

For purposes of the 2023 AIP, the Compensation Committee defined: (i) revenue to be gross sales minusreturns, discounts and allowances and minusintercompany sales, and (ii) adjusted EBITDA to be operating income plusdepreciation and amortization plus/minusnon-cashpension impact and plus/minusearnout/deferred purchase price accruals and certain acquisition-related charges, subject to certain exceptions which is consistent with the calculation of adjusted EBITDA that we report with our quarterly earnings. The revenue and adjusted EBITDA definitions did not change from the prior year. The 2023 revenue target of $1,299 million and adjusted EBITDA target of $414 million, represented a 5% increase and a 7% increase, respectively, from prior-year results. These targets were directly tied to the Company's annual operating plan.

COMPENSATION DISCUSSION AND ANALYSIS (CONTINUED)

2023 Individual Performance

The Board and the Compensation Committee also considered individual performance when finalizing AIP awards for the CEO and other NEOs and decided not to make any upward or downward adjustments for individual performance.

2023 Final AIP Awards

The Compensation Committee determined the final 2023 AIP payouts by multiplying each NEO's target AIP opportunity by the final weighted payout factors as outlined below.

Long-Term Incentive Program Awards 2023-2025 Performance Period

The goal of our LTIP is to provide equity-based long-term incentive awards that link management interests to shareholder returns and focus management on our long-term performance.

In determining the LTIP award opportunity for the CEO and other NEOs, our Board and Compensation Committee consider a number of factors, including the Competitive Market, internal equity with peers at similar levels and cost (dilution and accounting cost), as well as tally sheet and wealth accumulation analyses.

COMPENSATION DISCUSSION AND ANALYSIS (CONTINUED)

LTIP awards for a given year are typically made shortly following the release of our financial results for our prior fiscal year. This governance practice is designed to allow the equity markets to absorb the announcement of earnings and performance guidance.

The Compensation Committee after discussion with its Compensation Consultant, decided to change the mix of vehicles for our LTIP to NEOs from 100% PSUs to 60% PSUs and 40% RSUs beginning in 2023 in order to better align with market practice and our compensation objectives, including access to high quality executives in a highly competitive talent market. The high proportion of PSUs reflects our pay-for-performancephilosophy. The time-based awards support retention and are linked to shareholder value and ownership, which are important goals of our executive compensation program.

The RSU grants will fully vest and be issued if the NEO is still actively employed and in good standing on March 1, 2026 (three-year cliff vesting). Three-year vesting is common in our industry and supports executive retention and alignment with shareholder value.

The 2023 LTIP PSU grants for the 2023 - 2025 performance period ("2023 LTIP PSU Awards") consisted of awards based on achievement of Absolute TSR (60% of the award), adjusted FCF (25% of the award) and MF adjusted EBITDA (15% of the award). The Compensation Committee recognized there is a strong market influence on MFV outside of leadership's control including expected macro-economic weakness. Therefore, the Committee moved from MFV to Mineral Fiber adjusted EBITDA, which is directly connected to leadership's decisions and actions to manage MFV growth investments and profitability.

Mr. Grizzle has post-vesting holding requirements for amounts payable above target for the 2023 performance-based equity grants. If earned, any shares earned above target must be held for one year following the vesting date.

2023 LTIP Performance Metrics and Weighting

The number of shares eligible to vest under the 2023 LTIP PSU Awards is based on the achievement of applicable performance targets relative to Absolute TSR, adjusted FCF and MF adjusted EBITDA targets during the performance

COMPENSATION DISCUSSION AND ANALYSIS (CONTINUED)

period (January 1, 2023 to December 31, 2025). The grants, intended to compensate based on long-term value creation, have a three-year performance period to allow a reasonable timeframe for value creation, challenging targets with a substantial payout upside for breakout performance, and a payout scale that defines meaningful performance hurdles. The PSUs for the NEOs can vest 50% of target at threshold performance to 275% of target at maximum performance, on a weighted-average basis. There is no payout below threshold performance.

Absolute TSR tracks the appreciation in share price of the Company's Common Stock, including dividends, and is annualized for the performance period. The ending share price for the Absolute TSR calculation will be based on the volume-weighted, average closing price of the Company's Common Stock for the highest consecutive 30 trading days in the 60-trading-day-periodbeginning with and immediately following January 2, 2026. The starting price was based on the volume-weighted average of the highest consecutive 30 trading days in the subsequent 60-trading-day-periodclosing price of the Company stock for the highest 30 trading days immediately following January 2, 2023, resulting in $79.00 per share. Share repurchases only impact Absolute TSR to the extent they affect our stock price.

Adjusted FCF is defined as cumulative three-year cash flow from operations, minus (i) cash payments to purchase property, plant and equipment (Cap Ex), plus (ii) the return of investment from WAVE. The Adjusted FCF definition differs from that used for external reporting purposes due to the exclusion of proceeds from company-owned life insurance, which are classified as a component of Cash Flows from Investing Activities on our Consolidated Statements of Cash Flows within our Annual Report on Form 10-K.

MF adjusted EBITDA is defined as cumulative three-year operating income plusdepreciation, plus/minusenvironmental site expenses, plus/minusrestructuring charges and related costs and certain acquisition-related charges, subject to certain exceptions which is consistent with the calculation of adjusted EBITDA that we report with our quarterly earnings. The Mineral Fiber definition is consistent with that used for the external reporting segment.

2023 Target LTIP

The Compensation Committee annually determines the LTIP target opportunity (expressed as a percent of base salary) based on each NEO's role, responsibility, alignment with similar positions internally and the external Competitive Market, as well as a review of tally sheets and wealth accumulation analyses.

After a review of individual performance and Competitive Market data during the Compensation Committee meeting held in February 2023, the Compensation Committee increased Mr. Grizzle's target LTIP opportunity in 2023 to $5 million. 

COMPENSATION DISCUSSION AND ANALYSIS (CONTINUED)

Other Long Term Awards - Issued in 2023

On April 28, 2023, the independent directors, following the recommendation of the Compensation Committee, approved a grant of time-based restricted stock units to Mr. Grizzle with a target value of $5.0 million that vests in full on the third anniversary of the grant date. The award is intended to incentivize Mr. Grizzle, who on the date of grant was 61 years old, to continue his employment as President and CEO of the Company. In making the award, the independent directors considered Mr. Grizzle's strong performance and leadership of the Company, his importance to the execution of the Company's strategic priorities, and to facilitate a comprehensive CEO succession planning process. The independent directors determined to grant this award to serve as an additional retention tool in a highly competitive environment for senior executives with Mr. Grizzle's skills, experience and track record of strong performance.

In addition, Ms. Maheshwari received a one-timeRSU grant upon hire valued at $150,000. The RSU award was scheduled to vest over three years, vesting one-thirdeach year. Ms. Maheshwari left the organization on February 29, 2024.

Payout of 2021-2023 Performance-Based Restricted Stock Units

The performance for PSUs awarded in 2021 for the 2021 to 2023 performance period was determined on April 4, 2024. The awards were based on Absolute TSR, adjusted FCF and MFV over the performance period. In 2021, the Compensation Committee granted PSUs to Tier I (CEO and his direct reports) to vest based on achievement of

Absolute TSR (60% of the award), adjusted FCF (30% of the award) and MFV (10% of the award) and Tier II (below CEO and his direct reports) to vest based on achievement of Absolute TSR (30% of the award), adjusted FCF (60% of the award) and MFV (10% of the award).

Based upon performance during the measurement period, the Absolute TSR achievement for the 2021 to 2023 period was 12.01%, with a calculated price of $124.04 compared to the starting price for the TSR PSUs of $88.27. This exceeded our 10% annualized TSR target, resulting in a 130% payout under this metric. The cumulative adjusted FCF was $670 million for the performance period, below our target of $687 million. The Compensation Committee approved a payout factor of 94%. The MFV was below threshold for the performance period, resulting in no payout under this metric. Based on the metrics and the certified Absolute TSR and adjusted FCF results, the PSUs for Messrs. Grizzle and Hershey vested at 106% of target (Tier I). Mr. Calzaretta was in Tier II at the time of the 2021 - 2023 PSU grant. His PSUs vested at 96% of target. Mr. So and Ms. Maheshwari were not employed by us at the time of the commencement of the measurement period.

COMPENSATION DISCUSSION AND ANALYSIS (CONTINUED)

2024 Compensation Program Design

For 2024, the Compensation Committee reviewed the design of our executive compensation program and decided to maintain the 2023 metrics for our AIP (Revenue and adjusted EBITDA) and PSUs, namely Absolute TSR, adjusted FCF and MF adjusted EBITDA.

ADDITIONAL INFORMATION REGARDING OUR COMPENSATION PROGRAMS

Qualified and Non-QualifiedDefined Benefit Pension Plans

None of our NEOs participated in the Company's qualified defined benefit pension plan, the U.S. Retirement Income Plan ("RIP"), which was closed to newly hired salaried employees after January 1, 2005. Pension benefits were frozen for all salaried employees on December 31, 2017.

A non-qualifieddefined benefit pension plan, the Retirement Benefit Equity Plan ("RBEP"), pays benefits that cannot be paid under the RIP due to statutory limits. This plan was also closed to newly hired salaried employees after January 1, 2005 and RBEP benefits were frozen on December 31, 2017. None of our NEOs participated in the Company's RBEP.

Qualified Defined Contribution Savings Plan and Non-qualified Deferred Compensation Plan

The Company maintains a 401(k) plan. For salaried employees, we provide a 401(k) match of 100% on the first 4% of employee contributions and a 50% match on the next 4% of employee contributions for a maximum company match of 6%. All NEOs participated in this program in 2023.

The Company offers an unfunded, nonqualified deferred compensation plan, the Armstrong Nonqualified Deferred Compensation Plan ("NQDCP"), to restore Company contributions that would be lost due to Internal Revenue Code limits on compensation that can be taken into account under the Company's tax-qualified401(k) plan and to allow participants to voluntarily elect to defer base salary and AIP until a future date.

Participants in the NQDCP receive a Company match identical to the 401(k) Company match on compensation in excess of the Internal Revenue Code limits, up to a maximum contribution of 6% of eligible earnings. All NEOs participated in this program in 2023.

Severance Arrangements

Each NEO has a severance agreement with the Company. These agreements are designed to:

COMPENSATION DISCUSSION AND ANALYSIS (CONTINUED)

Payments upon Termination of Employment

Our severance arrangements provide for certain cash severance benefits if the executive's employment is terminated by the Company without Cause or by the executive for Good Reason (as such terms are defined in the severance agreement). Under the severance agreements that apply in absence of a change in control, the severance benefit is equal to (i) 1.5 times (two times in the case of Mr. Grizzle) the executive's then-current annual base salary plus target annual incentive under the AIP program, payable in a lump sum, and (ii) a pro-ratedannual incentive bonus based on actual performance for the year of termination, payable at the time that bonuses are paid to employees of the Company generally.

Under each executive's severance agreement, the executive is entitled to receive severance payments upon involuntary termination without Cause or termination for Good Reason within two years following a change in control ("CIC"), or within six months preceding a CIC if the termination is in connection with a potential CIC. In a CIC, the severance is equal to (i) two times (2.5 times in the case of Mr. Grizzle) the executive's then-current annual base salary plus target annual incentive under the AIP program, payable in a lump sum, and (ii) a pro-ratedannual incentive bonus based on actual performance for the year of termination, payable at the time that bonuses are paid to employees of the Company generally.

None of the severance agreements provide for tax gross-upsunder Sections 280G and 4999 of the Internal Revenue Code. For more information regarding our NEO separation arrangements, please refer to the "Potential Payments upon

Termination or Change in Control" section on page 54.

Stock Ownership Guidelines

The Compensation Committee reviews our NEOs' compliance with applicable stock ownership guidelines to foster long-term ownership of company stock and further align the NEOs' interests with those of shareholders. Ownership requirements and progress toward their achievement are reviewed annually as part of the compensation planning process. A significant percentage of each NEO's compensation is directly linked to our stock price performance via LTIP awards. In 2023, Meridian benchmarked our stock ownership guidelines and recommended modifications which were implemented after consultation with the Compensation Committee: create three tiers of ownership based on position, cease counting "in-the-money"stock options towards compliance with the guidelines, and modify the retention ratio from 100% to 50% of the net shares acquired upon any vesting or exercise of equity awards until the stock ownership guidelines are met.

The stock ownership guidelines for our NEOs are calculated as a fixed number of shares using a required ownership multiple, the executive's annual base salary as of a certain date, and the stock price as of a fixed date. The required ownership multiple is six times annual base salary for our CEO, three times annual base salary for Messrs. Calzaretta and Hershey and one and one-halftimes base salary for Mr. So (and was for Ms. Maheshwari).

For purposes of the stock ownership guidelines, we include direct ownership of shares and stock units held under employee plans. Stock Options and PSUs are not included in determining whether an executive has achieved the ownership levels.

The stock ownership guidelines require achievement of the ownership multiple within five years from date of hire or promotion into the role for the NEOs.

The Compensation Committee last reviewed the NEOs' progress toward meeting the stock ownership requirements in December 2023. As of December 2023, Messrs. Grizzle and Hershey had met their ownership requirements. Messrs. Calzaretta and So have five years from date of hire or promotion to achieve the guidelines.

COMPENSATION DISCUSSION AND ANALYSIS (CONTINUED)

Restrictive Covenants

Each NEO has a restrictive covenants agreement as part of their severance agreement. The agreements require the following:

Recoupment (Clawback) Policies

Mandatory Clawback Policy

Effective October 18, 2023, the Board of Directors implemented an Incentive Compensation Recoupment Policy. The policy was adopted in compliance with the rules implemented by the SEC under the Dodd-Frank Wall Street Reform and Consumer Protection Act and corresponding NYSE listing standards.

If the Company is required to prepare an accounting restatement (including a "Big R" or a "little r" restatement) due to material noncompliance with any federal securities laws, any Erroneously Awarded Compensation Received by a Covered Executive during the applicable three-year lookback period must be forfeited or paid back to the Company reasonably promptly (as such terms are defined in the Mandatory Clawback Policy).

"Erroneously Awarded Compensation" is limited to certain Section 16 officer compensation, including our NEOs, that is granted, earned or vested based wholly or in part upon the attainment of a financial reporting measure, such as PSUs and annual incentive plan pay outs.

Compensation must be "Received" (as defined by the NYSE listing standards) on or after the effective date of the applicable NYSE listing standards to be subject to recovery, among other limitations. Compensation is deemed "Received" in the Company's fiscal period during which the financial reporting measure specified in or otherwise relating to the applicable award is attained.

Amounts of Erroneously Awarded Compensation are recoverable to the extent they exceed the amount that otherwise would have been granted, vested or paid had such amount been determined based on the applicable restatement, computed on a pre-taxbasis.

The Compensation Committee is generally required to pursue (and does not have discretion to waive) recovery in the event of an accounting restatement, except if it determines that recovery is impracticable, in accordance with narrow exceptions described in the Incentive Compensation Recoupment Policy and in accordance with the SEC clawback rule and corresponding NYSE listing standards. Accordingly, whether recovery is sought under the Incentive Compensation Recoupment Policy is not dependent on a Covered Executive's commission of fraud or misconduct or consideration of any other mitigating circumstances, including the relative culpability, if any, of any Covered Executive in the events that gave rise to the triggering of an accounting restatement.

Other Recoupment Provisions

Under our 2022 ECIP, the Compensation Committee has the ability to exercise discretion and take action to recoup settled or unsettled stock-based and cash awards from a plan participant in the following events:

COMPENSATION DISCUSSION AND ANALYSIS (CONTINUED)

All of our NEOs are subject to the above recoupment terms of the plan.

Prohibition on Hedging and Derivative Trading

All members of our Board and senior management, including our NEOs and certain other employees, are required to clear any transaction involving Company securities with our General Counsel's office prior to entering into such transaction.

By policy, we prohibit derivative transactions in our Company securities, including:

We permit senior management to use stock trading plans that comply with Rule 10b5-1of the Exchange Act. All such plans are subject to our

pre-approval,and the ability to enter into such plans remains subject to policy prohibitions on trading while in possession of material non-publicinformation.

Assessment and Management of Risk

We monitor the risks associated with our compensation program on an ongoing basis. In addition, we are committed to performing formal assessments on a periodic basis. At the conclusion of the most recent analysis (conducted in 2023) of our compensation programs and associated risks, it was the assessment of the Compensation Committee that our compensation programs are structured and operated with an appropriate balance of risk and reward and, by their design, do not encourage executives to take unnecessary, excessive, or inappropriate risks and do not create risks reasonably likely to have a material adverse effect on the Company. Accordingly, there were no material adjustments made to our compensation policies and practices. We will continue to monitor our compensation policies and practices to determine whether our risk management objectives are being met with respect to incentivizing the Company's employees.

Tax Deductibility of Compensation

Section 162(m) of the Internal Revenue Code imposes a $1 million limit on the amount a public company may deduct for compensation paid to certain of the Company's highest paid officers.

For 2023, the executive officers to whom the Section 162(m) deduction limit applies included the Company's Chief Executive Officer and the Chief Financial Officer, the next three most highly compensated executive officers, and any persons who were such "covered employees" in 2017 or a later year.

The Compensation Committee considers both tax and accounting treatment in establishing our compensation program. The Compensation Committee retains discretion to authorize compensation arrangements that are not fully tax deductible as it deems appropriate.

COMPENSATION COMMITTEE REPORT

2023 SUMMARY COMPENSATION TABLE

GRANTS OF PLAN-BASED AWARDS

OUTSTANDING EQUITY AWARDS AT FISCAL YEAR-END