Cornerstone Building Brands : 1Q2021 Supplemental EarningsPresentation

1Q 2021

Supplemental Earnings Presentation

May 11, 2021

Disclaimers

Forward-Looking Statements

Certain statements and information in this presentation may constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as "believe," "anticipate," "guidance," "plan," "potential," "expect," "should," "will," "forecast," "target" and similar expressions are forward-looking statements within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995. These forward-looking statements reflect our current expectations, assumptions and/or beliefs concerning future events. As a result, these forward-looking statements rely on a number of assumptions, forecasts, and estimates and, therefore, these forward-looking statements are subject to a number of risks and uncertainties that may cause the Company's actual performance to differ materially from that projected in such statements. Such forward-looking statements may include, but are not limited to, statements concerning our market commentary and performance expectations, including our second quarter 2021 forecasted net sales, gross profit, and Adjusted EBITDA, and our fiscal year 2021 forecasted capital spending, cost savings initiatives, return of near-term expenses, net debt leverage, cash interest expense, cash tax rate and other consolidated financial performance guidance. Among the factors that could cause actual results to differ materially include, but are not limited to, industry cyclicality and seasonality and adverse weather conditions; challenging economic conditions affecting the nonresidential construction industry; downturns in the residential new construction and repair and remodeling end markets, or the economy or the availability of consumer credit; volatility in the United States ("U.S.") economy and abroad, generally, and in the credit markets; the severity, duration and spread of the COVID-19 pandemic, as well as actions that may be taken by the Company or governmental authorities to containCOVID-19 or to treat its impact; impairment of goodwill and/or intangible assets; our ability to successfully develop new products or improve existing products and market acceptance of such products; the effects of manufacturing or assembly realignments; seasonality of the business and other external factors beyond our control; commodity price volatility and/or limited availability of raw materials, including steel, PVC resin, glass and aluminum; our ability to identify and develop relationships with a sufficient number of qualified suppliers and to avoid a significant interruption in our supply chains; retention and replacement of key personnel; enforcement and obsolescence of our intellectual property rights; costs related to compliance with, violations of or liabilities under environmental, health and safety laws; changes in building codes and standards; competitive activity and pricing pressure in our industry; our ability to make strategic acquisitions accretive to earnings and achieve expected cost savings from historical acquisitions; our ability to carry out our restructuring plans and to fully realize the expected cost savings; global climate change, including legal, regulatory or market responses thereto; breaches of our information system security measures; damage to our computer infrastructure and software systems; necessary maintenance or replacements to our enterprise resource planning technologies; potential personal injury, property damage or product liability claims or other types of litigation; compliance with certain laws related to our international business operations; inability to attract and retain employees, increases in labor costs, potential labor disputes, union organizing activity and work stoppages at our facilities or the facilities of our suppliers; significant changes in factors and assumptions used to measure certain of our defined benefit plan obligations and the effect of actual investment returns on pension assets; the cost and difficulty associated with integrating and combining acquired businesses; volatility of the Company's stock price; substantial governance and other rights held by the Investors; the effect on our common stock price caused by transactions engaged in by the Investors, our directors or executives; our substantial indebtedness and our ability to incur substantially more indebtedness; limitations that our debt agreements place on our ability to engage in certain business and financial transactions; our ability to obtain financing on acceptable terms; downgrades of our credit ratings; and the effect of increased interest rates on our ability to service our debt. See also the "Risk Factors" in the Company's Annual Report on Form 10-K for the fiscal year ended December 31, 2020 to be filed with the SEC on the date hereof and other risks described in documents subsequently filed by the Company from time to time with the SEC, which identify other important factors, though not necessarily all such factors, that could cause future outcomes to differ materially from those set forth in the forward-looking statements. The Company expressly disclaims any obligation to update these forward-looking statements, whether as a result of new information, future events, or otherwise.

Non-GAAP Financial Measures

This presentation includes certain "non-GAAP financial measures" as defined under the Securities Exchange Act of 1934 and in accordance with Regulation G. Management believes the use of such non-GAAP financial measures assists investors in understanding the ongoing operating performance of the Company by presenting the financial results between periods on a more comparable basis. Such non-GAAP financial measures should not be construed as an alternative to reported results determined in accordance with U.S. GAAP. We have included reconciliations of these non-GAAP financial measures to the most directly comparable financial measures calculated and provided in accordance with U.S. GAAP in the Appendix to this presentation. A reconciliation of the forecasted range for Adjusted EBITDA for the second quarter of 2021 is not included in this presentation due to the number of variables in the projected range and because we are currently unable to quantify accurately certain amounts that would be required to be included in the GAAP measure or the individual adjustments for such reconciliation. In addition, we believe such reconciliation would imply a degree of precision that would be confusing or misleading to investors.

2

Financial Results Summary

1Q 2021 vs Pro Forma1 1Q 2020

RECORD FIRST-QUARTER FINANCIAL RESULTS

Net Sales	Adjusted EBITDA1	Adj. EBITDA1 Margin	Net Debt Leverage2
$1,267 million	$139 million	11.0%	4.6x

+13%	+42%	+230bps	Improved
			>1/2 turn
First quarter 2021 had ~5% fewer ship days than first quarter 2020
1 See Appendix for reconciliations of non-GAAP financial measures.			3
2 Net debt leverage is defined as net debt divided by LTM pro forma Adjusted EBITDA.

Key Takeaways

Robust residential end-market momentum across all channels

• Incoming order rate is increasing and significantly higher than prior year
• Utilization rates are higher, restoring our service proposition

Improving outlook for low-risenon-residentialend-market

• American Institute of Architects' ABI reaches highest point in over a decade
• Commercial segment volumes 5% higher sequentially; incoming order rates increasing

Material supply shortages and rising commodity costs persist

• Aggressive price actions taken to combat commodity costs at historic highs
• Strong supplier collaboration to effectively navigate through material constraints

Track record of profitable growth and margin expansion

• Capturing value from automation investments and continuous improvement initiatives
• Inflationary environment expected to compress margins in the short term

Advancing strategy and market penetration with inorganic investments

• Recent acquisitions increase scale, strengthen product portfolio and provide value from synergies

Stronger capital structure from debt refinancing and redemption of unsecured notes

4

Positioning for Sustainable Growth

2021 KEY PRIORITIES

Advance	Elevate the	Operate	Maintain
Our Strategy	Customer	with Excellence	Financial
through market	Experience	through automation	Discipline
penetration, inorganic	by being the	and process optimization	through higher
opportunities and	partner of choice	with safety as the priority	earnings and lower
product innovation			net debt leverage

The information on this slide represents management's expectations of future performance and is subject to a number of risks and uncertainties.		5
See "Forward-Looking Statements" on slide 2.