Virtual Meeting Only – No Physical Meeting Location

This proxy statement is furnished to stockholders of NCICornerstone Building Systems,Brands, Inc. (“NCI,Cornerstone Building Brands,” the “Company,” “we,” and “us”) in connection with the solicitation of proxies to be used at our Annual Meeting of Stockholders (the “Annual Meeting”) to be held virtually solely online via live webcast on Thursday, May 23, 201920, 2021 at 10:00 a.m. EDT.EDT at www.proxydocs.com/CNR. By granting a proxy, you authorize the persons named in the proxy to represent you and vote your shares at the Annual Meeting. Those persons will also be authorized to vote your shares to adjourn the Annual Meeting from time to time and to vote your shares at any adjournments or postponements of the Annual Meeting. Stockholders have a choice of voting over the Internet, at www.investorvote.com/NCSwww.proxypush.com/CNR(registered stockholders only), by telephone using the number 1-800-652-8683,1-844-927-1815, or by mail using a traditional proxy card. The deadline for voting by telephone or electronically is 5:00 p.m. EDT, on May 22, 2019.

If you give a proxy on the enclosed form, or by telephone or the Internet, you may revoke it at any time before it is exercised at the Annual Meeting by (1) delivering written notice of revocation to the Corporate Secretary of NCI,the Company, (2) signing, dating and delivering to the Corporate Secretary of NCIthe Company a later dated proxy at our principal executive offices, which are located at 5020 Weston Parkway, Suite 400, Cary, North Carolina 27513, or (3) virtually attending the Annual Meeting and voting in person by completing a ballot at the Annual Meeting. Attendanceonline. Virtual attendance at the Annual Meeting will not, in itself, constitute revocation of a completed and delivered proxy card.

If you are a street name stockholder (meaning that your shares are held in a brokerage account by a bank, broker or other nominee) and you vote by proxy, you may change your vote by submitting new voting instructions to your bank, broker or nominee in accordance with that entity’s procedures.

We are first sending this proxy statement and the enclosed proxy form to stockholders on or about April 22, 2019.

When you have appropriately specified how your proxy should be voted, the proxy will be voted accordingly. If you properly complete and return a proxy, but do not indicate any contrary voting instructions, your shares will be voted as follows:

At the discretion of the proxy holders, either FOR or AGAINST any other matter or business that may properly come before the Annual Meeting.

Unless otherwise noted, the following tables set forth, as of April 8, 20192021 (the “Ownership Date”), the number of shares of our equity securities beneficially owned by (1) each person or group known by us to own beneficially more than 5% of the outstanding shares of any class of our equity securities, (2) each director and nominee for director, (3) each of our named executive officers identified under the caption “Executive Compensation,” and (4) all current directors and executive officers as a group. Except as otherwise indicated, each of the persons or groups named below has sole voting power and investment power with respect to the Common Stock. Unless otherwise noted, the mailing address of each person or entity named below is 5020 Weston Parkway, Suite 400, Cary, North Carolina 27513.

CD&R Pisces GP, as the general partner of CD&R Pisces, may be deemed to beneficially own the shares of Common Stock shown as beneficially owned by CD&R Pisces. CD&R Pisces GP expressly disclaims beneficial ownership of the Common Stock of which CD&R Pisces has beneficial ownership.

Investment and voting decisions with respect to the shares of Common Stock held by CD&R Pisces or CD&R Pisces GP are made by an investment committee comprised of more than ten individuals (the “CD&R Pisces Investment Committee”). All members of the CD&R Pisces Investment Committee disclaim beneficial ownership of the shares of Common Stock shown as beneficially owned by CD&R Pisces.

CD&R Pisces GP expressly disclaims beneficial ownership of the shares held by CD&R Pisces and the restricted shares held by CD&R, LLC as assignees of director compensation payable to Messrs. Krenicki, Sleeper and Zrebiec. Each of CD&R Pisces and CD&R Pisces GP expressly disclaim beneficial ownership of the restricted shares held by CD&R, LLC as assignees of director compensation payable to Messrs. Krenicki, Sleeper and Zrebiec. CD&R, LLC expressly disclaims beneficial ownership of the shares held by CD&R Pisces.

The address for CD&R Pisces and CD&R Pisces GP is c/o Maples Corporate Services Limited, P.O. Box 309, Ugland House, South Church Street, George Town, Grand Cayman, KY1-1104, Cayman Islands. The address for CD&R, LLC is 375 Park Avenue, 18^th Floor, New York, NY 10152.

Does not include 120,626141,050 restricted shares of Common Stock and 20,424 restricted stock units issued to Clayton, Dubilier & Rice, LLC (“CD&R, LLC”), as assignee of director compensation payable to Messrs. John Krenicki, Nathan K. Sleeper and Jonathan L. Zrebiec.

The general partner of each of the CD&R Fund VIII Investors is CD&R Associates VIII, Ltd., whose sole stockholder is CD&R Associates VIII, L.P. The general partner of CD&R Associates VIII, L.P. is CD&R Investment Associates VIII, Ltd.

CD&R Investment Associates VIII, Ltd. is managed by a two-person board of directors. Donald J. Gogel and Kevin J. Conway, as the directors of CD&R Investment Associates VIII, Ltd., may be deemed to share beneficial ownership of the shares of Common Stock shown as beneficially owned by the CD&R Fund VIII Investors. Such persons expressly disclaim such beneficial ownership.

Investment and voting decisions with respect to the shares of Common Stock held by each of the CD&R Fund VIII Investors are made by an investment committee comprised of more than ten individuals (the “CD&R Fund VIII Investment Committee”). All members of the CD&R Fund VIII Investment Committee disclaim beneficial ownership of the shares of Common Stock shown as beneficially owned by the CD&R Fund VIII Investors.

The presence in person or by proxy of the holders of a majority of the voting power of the stock entitled to vote at an Annual Meeting is necessary to constitute a quorum at the Annual Meeting. Each outstanding share of Common Stock is entitled to one vote. All routine matters will be decided by the vote of a majority of the votes cast by the stockholders present in person or by proxy and entitled to vote on the matter, a quorum being present.

Pursuant to the terms of the Merger Agreement, on November 16, 2018, the Company entered into a stockholders agreement (the “New Stockholders“Stockholders Agreement”) between the Company, CD&R Pisces, the CD&R Fund VIII Investors (together with CD&R Pisces, the “CD&R Investors”), Atrium Intermediate, GGC BP, and AIC Finance Partnership, L.P., a Cayman Islands exempted limited partnership (“AIC”, and together with Atrium Intermediate and GGC BP, each individually, a “Golden Gate Investor,” and collectively, the “Golden Gate Investors”).

Those nominees receiving a plurality of all of the votes cast on Proposal 1 at the Annual Meeting shall be elected to our Board. Pursuant to the New Stockholders Agreement, the CD&R Investors and the GG Shareholders, which own or beneficially own shares of Common Stock representing approximately 49.4%49.28% and 13.3%5.96%, respectively, of our outstanding voting power as of April 8, 2019,2021, are required to vote for the election as directors each of the nominees listed under “Election of Directors,” other than Mr. Zrebiec.

The total number of votes cast on Proposal 2, regarding the frequency of required stockholder approval of the Company’s compensation philosophy, policies and procedures described in the Compensation Discussion & Analysis, or “CD&A” must represent at least the majority of the outstanding voting power of NCI entitled to vote on the proposal on the record date for determining stockholders entitled to vote at the Annual Meeting. The CD&R Investors, which own or beneficially own shares of Common Stock representing approximately 49.4% of our outstanding voting power as of April 8, 2019, have expressed their intention to vote for a frequency of  “every year” (an annual vote) in Proposal 2.

Our Third Amended and Restated Certificate of Incorporation (the “Certificate of Incorporation”) and SixthSeventh Amended and Restated By-Laws (the “By-Laws”“By-Laws”), together with the New Stockholders Agreement, provide that the number of directors on our Board initially following the consummation of the Merger shall be fixed at twelve, and shall be fixed from time to time exclusively pursuant to a resolution adopted by a majority of our Board. The number of members constituting our Board is currently fixed at twelve, including one vacancy as of the date hereof.

In accordance with our Certificate of Incorporation and By-Laws, our Board is divided into three classes, as nearly equal in number as reasonably possible, and members are elected for a term of office expiring at the third succeeding annual stockholders’ meeting following their election to office or until a successor is duly elected and qualified. Except as otherwise provided by the New Stockholders Agreement, under our By-Laws, newly created directorships resulting from any increase in the authorized number of directors or any vacancies on our Board resulting from death, resignation, retirement, disqualification, removal from office or other cause shall be filled only by a majority of the votes that can be cast by directors then in office, though less than a quorum, and directors so chosen hold office until the Annual Meeting of stockholders at which the term of office of the class to which the director has been elected expires. The terms of office of each of the Class III directors expire at this Annual Meeting and the terms of office of each of the Class III and Class III directors expire at the Annual Meetings in 20212022 and 2020,2023, respectively. Under our By-Laws, no person may stand for election as a director if, on the date of any annual or special meeting held for the purpose of electing directors, such person shall have surpassed the age of 75; however, those directors who are then serving on the boardBoard of directorsDirectors and have already reached the age of 75 as of November 16, 2017 may stand for election as a director if, on the date of any annual or special meeting held for the purpose of electing directors, such person shall not have surpassed the age of 78.

Four Class III directors are to be elected at the Annual Meeting for a term expiring at the Annual Meeting to be held in 2022,2024, or until their respective successors are duly elected and qualified or until their resignation. If, at the time of or prior to our Annual Meeting, any of the nominees should be unable or decline to serve, the discretionary authority provided in the proxy may be used to vote for a substitute or substitutes designated by our Board. Our Board has no reason to believe that any substitute nominee or nominees will be required. However, if a nominee should become unable or unwilling to serve for any reason, proxies may be voted for another person nominated as a substitute by our Board, or our Board may reduce its size. No proxy will be voted for a greater number of persons than the number of nominees named herein.

Our Board believes that each of our directors is highly qualified to serve as a member of our Board. Each of the directors has contributed to the mix of skills, core competencies and qualifications of our Board. Our directors are highly educated and have diverse backgrounds and talents and extensive track records of success in what we believe are highly relevant positions with some of the most reputable organizations in the world. Our Board has also considered the fact that all of our directors have worked for, or served on the boards of directors of, a variety of companies in a wide range of industries. Many of our directors also have served as directors of our companyCompany for many years and benefit from an intimate knowledge of our operations and corporate philosophy. Our Board believes that through their varying backgrounds, our directors bring a wealth of experiences and new ideas to our Board.

Described in the following pages are the principal occupations and positions and directorships for at least the past five years of our directors and director nominees, as well as certain information regarding their individual experience, qualifications, attributes and skills that led our Board to conclude that they should serve on the Board. There are no family relationships among any of our directors or executive officers.

Nominees for Election as Director

Class III Nominees for Election as Directors Who Will Serve Until the Annual Meeting to be Held in 2024:

Wilbert W. James, Jr.

Mr. James, age 65, has served as a director since May 2019. Mr. James is a member of the Compensation Committee and the Affiliated Transactions Committee. Mr. James had a 30-year career with Toyota Motors, with his most recent role as President of Toyota Motor Manufacturing of Kentucky (July 2010 – December 2017). In that role, he led Toyota’s largest automotive manufacturing plant in the world and oversaw a nearly $6 billion operation, which employed over 7,500 people. Additionally, he championed quality initiatives for Toyota’s fourteen North American manufacturing plants. Mr. James currently serves as a director on the boards of Columbia Forest Products and Atkore International. Mr. James earned an Associates in Applied Science from Old Dominion, a Bachelor of Science in Mechanical Engineering Technology from Old Dominion University, as well as an honorary doctorate of engineering from the University of Kentucky and an honorary degree from the University of Pikeville in 2015.

Director Qualifications: Mr. Zrebiec’s experience in the financial and investing community provides our Board with insight into business strategy, improving financial performance and the economic environment in which we operate. Mr. Zrebiec is a CD&R Investor Nominee (as defined in the New Stockholders Agreement).

Our current executive officers are as follows:

Alena S. Brenner, age 46,44, has served as Seniorour Executive Vice President, Chief Accounting OfficerGeneral Counsel and TreasurerCorporate Secretary since November 16, 2018. Mr. BoyleApril 2021. Before joining the Company, Ms. Brenner was Ply Gem Industries,employed by Ryder System, Inc.’s Chief Accounting Officer, where she advanced through various leadership roles since January 2012, most recently serving as Vice President and Treasurer from 2016 until November 16, 2018. Prior to this role, Mr. Boyle served as Ply Gem’s Corporate Controller from 2008 to 2016 participating in Ply Gem’s initial public offering process in 2013.Deputy General Counsel. Prior to joining Ply Gem, Mr. Boyle wasRyder System, Inc., Ms. Brenner served as Legal Director, Commercial and M&A for Anheuser-Busch InBev from July 2010 to January 2012. Ms. Brenner began her legal career at Hunton Andrews Kurth LLP from September 2001 to July 2010. Ms. Brenner has a senior manager in the audit practice with PricewaterhouseCoopers LLP in Raleigh, NC working predominantly with manufacturing clients. Mr. Boyle graduatedB.S. from theCornell University of North Carolina-Chapel Hill in 1995 with a BSBA and a MasterJ.D. from Fordham University School of Accounting.

John L. Buckley, age 54,56, has served as our President, Siding Business Unit — Residential (formerly known as the Siding Division) since November 16, 2018. Prior to that, Mr. Buckley served as Ply Gem Industries, Inc.’s President of Siding, Fencing and Stone group from 2012 until November 16, 2018. Mr. Buckley joined Ply Gem in 1999, and prior to his appointment as President of the Siding, Fencing and Stone group he had served as Senior Vice President of Sales for Ply Gem’s siding and accessories subsidiaries. Prior to joining Ply Gem, Mr. Buckley worked for CertainTeed from 1991 to 1999, holding a variety of sales management positions. Mr. Buckley currently serves as the Chairman of the VSI Board of Directors and Chairman of the VSI Steering Committee and Primary Marketing Committee. Mr. Buckley received a BA in communications from the University of Michigan in 1986, and a MSA from Madonna University in 1991.

Jeffrey S. Lee, age 59, has served as our Executive Vice President, Chief Legal, Risk & Compliance Officer and Corporate Secretary since May 2017. Mr. Moore served as our Executive Vice President and General Counsel from December 2007 to May 2017, and as our Vice President and General Counsel from March 2003 to December 2007. Mr. Moore has served as a Vice President and General Counsel of all NCI divisions since January 1999 and as our Corporate Secretary since March 2005. Before joining NCI in January 1999, Mr. Moore was a partner in the Trial Section of Gardere Wynne Sewell LLP, a law firm based in Texas. Mr. Moore has a B.A. in Political Science from Southern Methodist University and a J.D. from the University of Tulsa College of Law. He is licensed to practice law in the State of Texas.

James F. Keppler, age 53, has served as our Executive Vice President, of Ply Gem Holdings, Inc.Operations since September 2020. Mr. Keppler was employed by Whirlpool Corporation (“Whirlpool”) from August 2004 until November 16, 2018. He2011 to 2020, where he served as Vice President, of Finance of Ply Gem Holdings Inc. from March 2000 to August 2004. He served as Corporate Controller and various other accounting positions at Nordyne, Inc., joining in 1990. Mr. Poe graduated from Southeast Missouri State University in 1984 with a BS in Accounting. Mr. Poe graduated from Fontbonne College in 1994 with an MBA.

This Compensation Discussion & Analysis (“CD&A”) provides information regarding NCI’sthe Company’s compensation programs for our Chief Executive Officer (“CEO”), our Chief Financial Officer (“CFO”), our former CEO, our former interim CFO,Commercial Business Unit, and our three other most highly compensated executive officers during the Transition Period. The CD&A is also intended to place in perspective the information for the Transition Period contained in the executive compensation tables that follow this discussion.

Throughout this discussion, the following individuals are referred to collectively as the “Named Executive Officers” or “NEOs” and are included in the Summary Compensation Table that follows this discussion:

To ensure the period described herein. However, as further describedsafety of our employees, we:

Despite the challenges presented by the COVID-19 pandemic in Item 112020, we made notable progress with several initiatives aimed at improving profitability and strengthening our balance sheet. In 2020, Adjusted EBITDA was on all time high of Amendment No. 1$609 million, an increase of 2.6% over prior year and adjusted EBITDA margin was 13.2%, a 120 basis point improvement versus 2019. We delivered cost savings of approximately $113 million throughout 2020, which was approximately $13 million more than target. We reduced cost in many areas of the businesses, including material sourcing, plant and back office rationalizations, process and labor savings from automation and many others. We ended 2020 with our seventh consecutive quarter of year-over-year pro forma adjusted EBITDA margin expansion, a 260 basis point improvement since 2018. For additional information regarding Adjusted EBITDA, including a detailed calculation and reconciliation to the Company’smost comparable GAAP measure, see page 39 of our Annual Report on Form 10-K filedfor the fiscal year ended December 31, 2020, under the heading “Non-GAAP Financial Measures.”

At our most recent shareholder advisory vote on executive compensation at our 20172020 Annual Meeting, more than 98% of the votes cast on the advisory “say-on-pay”“say-on-pay” resolution were voted in favor of the compensation philosophy, policies and procedures and the compensation of the NEOs as disclosed in our 20172020 proxy statement. The Compensation Committee viewed the result of this advisory vote as strongly supportive of our pay-for-performance philosophy. Our Compensation Committee continually evaluates NCI’sthe Company’s compensation practices so as to best align the interests of our senior executives and our stockholders and will continue to do so such that they remain aligned with our compensation objectives. Our Board, Compensation Committee and management team all value the opinions of our stockholders and are committed to considering their opinions in making these important decisions. In light of these results, the Compensation Committee maintained many of our existing executive compensation programs during the Transition Period, and made such changes to the long-term incentive compensation program that the Compensation Committee determined were necessary to align the goals of the Company’s management team and provide a unified incentive structure following the Merger.Fiscal 2020. See “Compensation Discussion & Analysis — Long-Term Incentive Compensation.”

To further align the interests of our senior management team with those of our stockholders, we have also have implemented stock ownership guidelines that requireunder which each of our NEOs is expected to acquire and hold a number of shares of our common stock having a value equal to a multiple of his or her annual salary. See “Compensation Discussion & Analysis — Stock Ownership Guidelines.”

Decisions regarding executive compensation are based primarily on the assessment by the Compensation Committee of each Named Executive Officer’s leadership and operational performance, and potential to enhance long-term value to NCI’sthe Company’s stockholders. Since Fiscal 2014 (with the exception of Fiscal 2016),February 2015, the Compensation Committee has retained a compensation consultant, Frederic W. Cook & Co. (“FW Cook”), to assist it in its comprehensive review of NCI’sthe Company’s executive compensation program. During the Transition Period,Fiscal 2020, FW Cook continued to advise the Compensation Committee regarding compensation packages for new hires and promotions and other governance related matters, as well as our director compensation arrangements (see “Executive Compensation — Compensation of Directors”). The Compensation Committee also relies on its judgment, prior experience, and the judgment of our CEO, Mr. Metcalf, about each individual Named Executive Officer in determining the amount and combination of compensation elements and whether each payment or award appropriately encourages and rewards performance. Key factors considered by the Compensation Committee in this regard include:

The Compensation Committee’s charter provides that it may retain advisors, including compensation consultants, in its sole discretion. In engagingThe Compensation Committee has assessed the independence of FW Cook the Compensation Committeepursuant to SEC and NYSE rules and has determined that FW Cook diddoes not have any economic interest or other relationship that would create a conflict with its services to the Compensation Committee.

In assessing compensation elements and making compensation decisions for our executive officers, our Compensation Committee considers the executive compensation practices of a peer group of companies of similar size to the Company in related industries. As disclosed in the Fiscal 2018Transition Period CD&A, our Compensation Committee substantially updated the compensation peer group in November 2018 with the assistance of FW Cook in order to reflect changes to the Company’s size, projected revenuenet sales and scope of business resulting from the Merger. The following peer group was used in making compensation decisions for our NEOs during the Transition Period: