Fiscal 2023 Third Quarter Results DECEMBER 5, 2023

© Core & Main All Rights Reserved. Confidential and Proprietary Information. 2 CAUTIONARY STATEMENTS Cautionary Note Regarding Forward-Looking Statements This presentation and accompanying discussion may include “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements include, without limitation, all statements other than statements of historical or current facts relating to our intentions, beliefs, assumptions or current expectations concerning, among other things, our future results of operations and financial position, business strategy and plans and objectives of management for future operations, including, among others, statements regarding expected growth, future capital expenditures, capital allocation and debt service obligations, and the anticipated impact on our business. Som e of the forward-looking statements can be identified by the use of forward-looking terms such as “believes,” “expects,” “may,” “will,” “shall,” “should,” “would,” “could,” “seeks,” “aims,” “projects,” “is optimistic,” “intends,” “plans,” “estimates,” “anticipates” or the negative versions of these words o r other comparable terms. Forward-looking statements are subject to known and unknown risks and uncertainties, many of which may be outside our control. We caution you that forward-looking statements are not guarantees of future performance or outcomes and that actual performance and outcomes, including, without limitation, our actual results of operations, financial condition and liquidity, and the development of the market in which we operate, may differ materially from those made in or suggested by the forward-looking statements contained in this presentation. In addition, even if our results of operations, financial condition, cash flows and the development of the market in which we operate, are consistent with the forward-looking statements contained in this presentation, those results or developments may not be indicative of results or developments in subsequent periods. A number of important factors, including, without limitation, the risks and uncertainties discussed under the captions “Risk Factors” in our Annual Report on Form 10-K for the fiscal year ended January 29, 2023 and our Quarterly Report on Form 10-Q for the three months ended October 29, 2023, could cause actual results and outcomes to differ materially from those reflected in the forward-looking statements. Furthermore, new risks and uncertainties emerge from time to time, and it is not possible for us to predict all risks and uncertainties that could have an impact on the forward-looking statements contained in this presentation. Factors that could cause actual results and outcomes to differ from those reflected in forward-looking statements include, without limitation: declines, volatility and cyclicality in the U.S. residential and non-residential construction markets; slowdowns in municipal infrastructure spending and delays in appropriations of federal funds; our ability to competitively bid for municipal contracts; price fluctuations in our product costs; our ability to manage our inventory effectively, including during periods of supply chain disruptions; our ability to continue our customer relationships with short-term contracts; risks involved with acquisitions and other strategic transactions, including our ability to identify, acquire, close or integrate acquisition targets successfully; the fragmented and highly competitive markets in which we compete and consolidation within our industry; the development of alternatives to distributors of our products in the supply chain; our ability to hire, engage and retain key personnel, including sales representatives, qualified branch, district and regional managers and senior management; our ability to identify, develop and maintain relationships with a sufficient number of qualified suppliers and the potential that our exclusive or restrictive supplier distribution rights are terminated; the availability and cost of freight; the ability of our customers to make payments on credit sales; changes in supplier rebates or other terms of our supplier agreements; our ability to identify and introduce new products and product lines effectively; the spread of, and response to public health crises and the inability to predict the ultimate impact on us; costs and potential liabilities or obligations imposed by environmental, health and safety laws and requirements; regulatory change and the costs of compliance with regulation; changes in stakeholder expectations in respect of environmental, social and governance and sustainability practices; exposure to product liability, construction defect and warranty claims and other litigation and legal proceedings; potential harm to our reputation; difficulties with or interruptions of our fabrication services; safety and labor risks associated with the distribution of our products as well as work stoppages and other disruptions due to labor disputes; impairment in the carrying value of goodwill, intangible assets or other long-lived assets; interruptions in the proper functioning of our and our third-party service providers’ information technology systems, including from cybersecurity threats; risks associated with exporting our products internationally; our ability to m aintain effective internal controls over financial reporting and remediate any material weaknesses; our indebtedness and the potential that we may incur additional indebtedness; the limitations and restrictions in the agreements governing our indebtedness, the Second Amended and Restated Agreement of Limited Partnership of Core & Main Holdings, LP as amended, and the Tax Receivable Agreements (as defined in our Quarterly Report on Form 10-Q); increases in interest rates and the impact of transitioning away from LIBOR, generally to Term SOFR (as defined in our Quarterly Report on Form 10-Q), as a benchmark rate in contracts; changes in our credit ratings and outlook; our ability to generate the significant amount of cash needed to service our indebtedness; our organizational structure, including our payment obligations under the Tax Receivable Agreements, which may be significant; our ability to sustain an active, liquid trading market for our Class A common stock; the significant influence that CD&R (as defined in our Quarterly Report on Form 10-Q) has over us and potential conflicts between the interests of CD&R and other stockholders; and risks related to other factors described under “Risk Factors” in our Annual Report on Form 10-K and our Quarterly Report on Form 10-Q for the three months ended October 29, 2023. These factors are not exhaustive, and new factors may emerge or changes to the foregoing factors may occur that could impact our business. Except to the extent required by law, we undertake no obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, which speak only as of the date of this presentation. Use of Non-GAAP Financial Measures In addition to providing results that are determined in accordance with U.S. Generally Accepted Accounting Principles (“GAAP” ), we present EBITDA, Adjusted EBITDA, Adjusted EBITDA margin, Operating Cash Flow Conversion and Net Debt Leverage, all of which are non-GAAP financial measures. These measures are not considered measures of financial performance or liquidity under GAAP and the items excluded therefrom are significant components in understanding and assessing our financial performance or liquidity. These measures should not be considered in isolation or as alternatives to GAAP measures such as net income or net income attributable to Core & Main, Inc., as applicable, cash provided by or used in operating, investing or financing activities, or other financial statement data presented in the financial statements as an indicator of our financial performance or liquidity. We use EBITDA, Adjusted EBITDA, Adjusted EBITDA margin, Operating Cash Flow Conversion and Net Debt Leverage to assess the operating results and effectiveness and efficiency of our business. We present these non-GAAP financial measures because we believe investors consider them to be important supplemental measures of performance, and we believe that these measures are frequently used by securities analysts, investors and other interested parties in the evaluation of companies in our industry. Non-GAAP financial measures as reported by us may not be comparable to similarly titled metrics reported by other companies and may not be calculated in the same manner. These measures have limitations as analytical tools, and you should not consider them in isolation or as substitutes for analysis of our results as reported under GAAP. Reconciliations of such non- GAAP measures to the most directly comparable GAAP measure and calculations of the non-GAAP measures are set forth in the appendix of this presentation. No reconciliation of the estimated range for Adjusted EBITDA, Adjusted EBITDA margin or Operating Cash Flow Conversion for fiscal 2023 are included herein because we are unable to quantify certain amounts that would be required to be included in net income attributable to Core & Main, Inc. or cash provided by or used in operating activities, the most directly comparable GAAP measures, without unreasonable efforts due to the high variability and difficulty to predict certain items excluded from Adjusted EBITDA. Consequently, we believe such reconciliation would imply a degree of precision that would be misleading to investors. In particular, the effects of acquisition expenses cannot be reasonably predicted in light of the inherent difficulty in quantifying such items on a forward-looking basis. We expect the variability of these excluded items may have an unpredictable, and potentially significant, impact on our future GAAP results. Presentation of Financial Information The accompanying financial information presents the results of operations, financial position and cash flows of Core & Main, Inc. (“Core & Main” or the “Company”) and its subsidiaries, which includes the consolidated financial information of Core & Main Holdings, LP, a Delaware limited partnership (“Holdings”) and its consolidated subsidiary, Core & Main LP, as the legal entity that conducts the operations of the Company. Core & Main is the primary beneficiary and general partner of Holdings and has decision making authority that significantly af fects the economic performance of the entity. As a result, Core & Main consolidates the consolidated financial statements of Holdings. All intercompany balances and transactions have been eliminated in consolidation. The Company records non-controlling interests related to Partnership Interests (as defined in our Quarterly Report on Form 10-Q) held by the Continuing Limited Partners (as defined in our Quarterly Report on Form 10-Q) in Holdings. The Company’s fiscal year is a 52 or 53-week period ending on the Sunday nearest to January 31st. Quarters within the fiscal year include 13-week periods, unless a fiscal year includes a 53rd week, in which case the fourth quarter of the fiscal year will be a 14-week period. Each of the three months ended October 29, 2023 and three months ended October 30, 2022 included 13 weeks and each of the nine months ended October 29, 2023 and nine months ended October 30, 2022 included 39 weeks.

© Core & Main All Rights Reserved. Confidential and Proprietary Information. 3 TODAY’S PRESENTERS Steve LeClair Chief Executive Officer Mark Witkowski Chief Financial Officer Robyn Bradbury VP, Finance & Investor Relations

Business Update STEVE LECLAIR

© Core & Main All Rights Reserved. Confidential and Proprietary Information. ▪ Municipal repair & replacement activity remains stable ▪ New residential lot development continues to improve ▪ Non-residential demand supported by diverse project exposure ▪ Medium to long-term market fundamentals remain positive 5 BUSINESS UPDATE End Markets Pricing Margins Cash Flow & Capital Allocation ▪ Roughly flat price contribution to net sales growth in Q3 ▪ Expect low single-digit price contribution for fiscal 2023 ▪ Non-discretionary nature of demand provides a resilient pricing framework ▪ Gross margins continue to normalize at a slower pace than previously anticipated ▪ Margin initiatives and M&A synergies continue to drive structural margin improvement ▪ Exceptional operating cash flow performance in Q3 supporting capital allocation priorities ▪ Executed one share repurchase transaction during the quarter and another after the quarter, deploying nearly $300M of capital ▪ Repurchased and retired 30 million shares year-to-date for $770M ▪ Ample capacity to continue executing organic and inorganic growth strategies, while returning capital to shareholders

© Core & Main All Rights Reserved. Confidential and Proprietary Information. 6 DRIVING SUSTAINABLE GROWTH THROUGH M&A Status Closed November 2023 Signed November 2023 Signed November 2023 # of Locations 1 1 4 Geography Ohio Minnesota Pennsylvania, South Carolina & West Virginia Product Lines Geosynthetics & Erosion Control Pipes, Valves & Fittings Storm Drainage Pipes, Valves & Fittings Fusible HDPE Solutions Combined Annualized Net Sales of ~$135M Enviroscape Granite Water Works Lee Supply Company

© Core & Main All Rights Reserved. Confidential and Proprietary Information. 7 60 – 70% Operating Cash Flow Conversion 30 – 50 bps Adjusted EBITDA Margin Enhancement +2 – 4% Growth from Acquisitions +2 – 4% Organic Above Market Volume Growth +2 – 4% Market Volume Growth Meters Fire Protection Storm Drainage Strategic Accounts Fusible HDPE Solutions Treatment Plant Geosynthetics Greenfield Expansion Pricing Analytics Sourcing Optimization Private Label Operational Excellence ANNUAL VALUE CREATION TARGETS

Financial Results MARK WITKOWSKI

© Core & Main All Rights Reserved. Confidential and Proprietary Information. $0.39 $0.65 $0.65 Q3'21 Q3'22 Q3'23 9 Q3 2023 FINANCIAL RESULTS Net Sales Gross Profit Adjusted EBITDA(1) Diluted Earnings Per Share ($ in Millions, Except Per Share Amounts) (1) Adjusted EBITDA and Adjusted EBITDA margin are non-GAAP financial measures. Refer to the appendix of the presentation for a reconciliation to the nearest GAAP measure. $1,405 $1,818 $1,827 Q3'21 Q3'22 Q3'23 $371 $500 $494 Q3'21 Q3'22 Q3'23 $189 $275 $260 Q3'21 Q3'22 Q3'23 +29% 1% 26.4% 27.5%+110 bps 27.0%(50 bps)% Margin % Margin(1) 13.5% 15.1%+160 bps 14.2%(90) bps (5%) +46% (1%) +35% +67% +0%

© Core & Main All Rights Reserved. Confidential and Proprietary Information. 10 CASH FLOW & BALANCE SHEET Operating Cash Flow Net Debt Leverage(3) Liquidity ($ in Millions) ABL Facility Available Cash & Cash Equivalents (1) Adjusted EBITDA is a non-GAAP financial measure. Refer to the appendix of the presentation for a reconciliation to the nearest GAAP measure. (2) Represents operating cash taxes paid to the IRS and other state & local taxing authorities. Does not include the portion of our tax obligation distributed to non-controlling interest holders as a financing cash outflow. (3) Net Debt Leverage represents gross consolidated debt net of cash & cash equivalents divided by Adjusted EBITDA for the last twelve months, which is a non-GAAP financial measure. Refer to the appendix of the presentation for a reconciliation to the nearest GAAP measure. Q3’22 Q3’23 Y-o-Y $ Adjusted EBITDA(1) $275 $260 ($15) Working Capital (58) 167 $225 Cash Interest (15) (19) (4) Cash Taxes(2) (45) (21) 24 Other (3) (14) (11) Operating Cash Flow $154 $373 $219 1.7x 1.5x Q3'22 Q3'23 $1,151 $1,335 Q3'22 Q3'23

© Core & Main All Rights Reserved. Confidential and Proprietary Information. GUIDANCE UPDATE 11 Key Metric FY23 Outlook Net Sales ($ in Millions) $6,650 - $6,750 Adjusted EBITDA ($ in Millions) $890 - $910 Adjusted EBITDA Margin 13.4% - 13.5% Operating Cash Flow Conversion(1) (% of Adjusted EBITDA) 110% - 115% ▪ Expect FY23 net sales growth to range from flat to +1% ̶ Municipal demand expected to remain stable through Q4 ̶ New residential lot development growth expected to improve sequentially and benefit from easier year-over-year comparisons ̶ Expect non-residential volumes in Q4 to be flat to slightly down on a year-over- year basis ▪ Expect initiatives to sustain gross margins at higher levels than previously anticipated ▪ Raising expectation for Adjusted EBITDA due to gross margin performance and confidence in our ability to sustain margins ▪ Raising expectation for operating cash flow conversion due to disciplined inventory optimization efforts Considerations (1) Defined as net cash provided by (used in) operating activities divided by Adjusted EBITDA for the period presented.

Appendix

© Core & Main All Rights Reserved. Confidential and Proprietary Information. 13 CORE & MAIN AT A GLANCE Key Business Highlights Branch Footprint Corporate HQ (1) As of the fiscal year ended January 29, 2023 and based on management estimates. (2) Adjusted EBITDA is a non-GAAP financial measure. Refer to the appendix of the presentation for a reconciliation to the nearest GAAP measure. ▪ Leading U.S. specialty distributor focused on water, wastewater, storm drainage and fire protection products, and related services ▪ Highly fragmented $40 billion addressable market(1) ▪ 1 of only 2 national distributors where scale matters ▪ ~320 branches in 48 states across the U.S. ▪ $6.6 billion of LTM Q3’23 net sales and $914 million of LTM Q3’23 Adjusted EBITDA(2) ▪ Balanced mix of sales across end markets, construction sectors and product lines ▪ Highly fragmented customer base of 60,000+ including municipalities, private water companies and professional contractors ▪ More than 200,000 SKUs ▪ 4,500+ suppliers, many of which have long-standing, often exclusive or restrictive, relationships with CNM Market Share(1) Market Mix(1) ~$40B(1) 17% Core & Main 83% Remaining Market 39% Non-Residential39% Municipal 22% Residential

© Core & Main All Rights Reserved. Confidential and Proprietary Information. PRODUCT & SERVICE OFFERING 14

© Core & Main All Rights Reserved. Confidential and Proprietary Information. BALANCED MIX ACROSS END MARKETS 15 ResidentialNon-ResidentialMunicipal New Lot Development Repair & ReplacementNew Development Repair & ReplacementRepair & Replacement Expansion of Service ▪ New development of water, sewer and storm drainage infrastructure for residential building sites ▪ Underground contractors install water and sewer pipes to connect the new development to existing infrastructure ▪ Products installed before single-family home breaks ground ▪ Typically funded by developers ▪ Large majority of our residential market ▪ Improvements to or replacement of existing infrastructure as part of a brownfield site development ▪ Typically funded by developers ▪ Smaller percentage of our residential market ▪ New development of water, sewer and storm drainage infrastructure for new commercial or industrial sites ▪ Installation of new fire protection systems in newly constructed commercial or multi-family buildings ▪ Includes balanced mix of road and bridge projects (DOT), which benefits our storm drainage product line ▪ Typically funded by developers, or by state and federal entities ▪ Roughly half of our non- residential market ▪ Improvements to or partial replacement of existing infrastructure as part of a brownfield site development ▪ Includes retrofit of existing fire protection systems in existing commercial or multi-family buildings to comply with changing regulations or layout ▪ Typically funded by developers, or by state and federal entities ▪ Roughly half of our non- residential market ▪ Improvements to or replacement of existing infrastructure ▪ Repairs and upgrades tend to be non-discretionary in nature ▪ Funded by local and state entities, or by the federal government ▪ Majority of our municipal market ▪ Expansion of infrastructure into new areas due to growth or population shifts ▪ Funded by local and state entities, or by the federal government. May be part of a public-private partnership ▪ Smaller portion of our municipal market 39% 39% 22% (1) Represents estimated end market exposure based on net sales for the fiscal year ended January 29, 2023. (1) (1) (1)

© Core & Main All Rights Reserved. Confidential and Proprietary Information. 16 WELL-POSITIONED TO WIN WITHIN COMPLEX INDUSTRY Differentiated Industry Highly Complex Specification & Regulation Specialized Product Requirements Limited Distribution Rights Fragmented Industry ▪ Local regulation and specification needs; strong participation in governing / regulating bodies ▪ Pre-project specification influence ▪ Local, regional & national product specialists required to support complex project needs ▪ Suppliers require local knowledge & experience to secure limited distribution rights ▪ Highly diversified supplier base & fragmented customer base creates need for scaled distribution Branch Network & Logistics ▪ Coordinated jobsite delivery & customer support ▪ Differentiated delivery capabilities Our Competitive Advantages Deep knowledge of products and local specifications, supported by consultative sales approach and delivery expertise Industry Expertise 320 branches across 48 states Partnering with 4,500+ suppliers to reach 60,000+ diverse customers Size & Unique Scalability Strong, long-standing customer & supplier relationships with access to 200K+ products with limited distribution rights Deep Customer & Supplier Relationships “One-stop-shop” for customer solutions, enabled by project value engineering and jobsite support Differentiated Services & Deep Product Portfolio Proprietary technology platforms drive operational efficiency and enhance customer experience Technology & Innovation Specific to our Industry Best Industry Talent People-first approach is critical to developing industry leaders and enabling local expertise, nationwide

© Core & Main All Rights Reserved. Confidential and Proprietary Information. 17 OUR APPROACH TO M&A October 2017 June 2018 July 2018 August 2018 January 2019 February 2019 October 2019 October 2019 March 2020 August 2020 March 2021 August 2021 October 2021 November 2021 March 2022 May 2022 June 2022 August 2022 October 2022 December 2022 March 2023 April 2023 April 2023 July 2023 November 2023 TBD TBD Driving Sustainable Growth Through M&A… July 2019 August 2021 October 2022 July 2023 …Leveraging Our Disciplined Approach Maximize Market Presence Drive Value Creation Leverage Entrepreneurial Culture ▪ Significant opportunity to fill existing geographies and product lines or expand into new geographies and product lines ▪ Ability to access attractive markets, new technologies and product innovations ▪ Diligent assessment of macro growth trends and competitive landscape ▪ Our size, scale and differentiated capabilities drives immediate synergistic value with a focus on people, process and strategy ▪ Past synergies have driven highly attractive returns on capital and support shareholder value creation ▪ Successful track record of retaining and promoting management and associates of acquired companies ▪ Our “local service, nationwide” philosophy incentivizes acquired companies to be entrepreneurial, making decisions grounded in a customer-centric approach

© Core & Main All Rights Reserved. Confidential and Proprietary Information. Pipes, Valves & Fittings Meters $55B to expand access to clean drinking water $13.5B $50B to protect against droughts, floods, heat and wildfires, in addition to major investments in weatherization and cybersecurity $2.5B Pipes, Valves & Fittings Storm Drainage $110B to repair roads and bridges and support major transformational projects $1.0B Storm Drainage Erosion Control $25B to create more modern, resilient and sustainable airport infrastructure $0.2B Fire Protection CNM Serviceable Opportunity / Representative Product Lines 18 CRITICAL INVESTMENTS FROM THE INFRASTRUCTURE INVESTMENT & JOBS ACT

© Core & Main All Rights Reserved. Confidential and Proprietary Information. CAPITAL ALLOCATION FRAMEWORK 19 Priority Uses for Capital Normalized Operating Cash Flow Target to be ~60-70% of Adjusted EBITDA Organic Growth & Operational Initiatives M&A Share Repurchases or Dividends Expect future capital expenditures to average ~0.5% of net sales Maintain a robust M&A pipeline and a disciplined approach. Expect continued M&A focused on geographic expansion, product line expansion, the addition of key talent and additional operating capabilities, while driving synergistic value creation Deploy surplus capital towards share repurchases and/or dividends Capital Allocation Framework

© Core & Main All Rights Reserved. Confidential and Proprietary Information. RECONCILIATION OF NON-GAAP MEASURES 20 (1) Includes depreciation of certain assets which are reflected in “cost of sales” in our Statement of Operations. (2) Represents expenses associated with acquisition activities, including transaction costs, post-acquisition employee retention bonuses, severance payments, expense recognition of purchase accounting fair value adjustments (excluding amortization) and contingent consideration adjustments. (3) Represents costs related to secondary offerings reflected in SG&A expenses in our Statement of Operations. ($ in Millions) Adjusted EBITDA & Adjusted EBITDA Margin October 29, 2023 October 30, 2022 October 31, 2021 October 29, 2023 October 30, 2022 October 29, 2023 October 30, 2022 Net income attributable to Core & Main, Inc. 112$ 111$ 64$ 308$ 312$ 362$ 360$ Plus: net income attributable to non-controlling interest 46 67 45 147 185 177 216 Net income 158 178 109 455 497 539 576 Depreciation and amortization (1) 38 37 37 111 107 147 143 Provision for income taxes 39 40 25 110 108 130 125 Interest expense 20 16 12 59 46 79 59 EBITDA 255$ 271$ 183$ 735$ 758$ 895$ 903$ Loss on debt modification and extinguishment - - 1 - - - - Equity-based compensation 3 2 2 8 9 10 12 Acquisition expenses (2) 1 1 3 4 3 6 4 Offering expenses (3) 1 1 - 3 1 3 3 Adjusted EBITDA 260$ 275$ 189$ 750$ 771$ 914$ 922$ Adjusted EBITDA Margin: Net Sales 1,827$ 1,818$ 1,405$ 5,262$ 5,277$ 6,636$ 6,523$ Adjusted EBITDA / Net Sales 14.2% 15.1% 13.5% 14.3% 14.6% 13.8% 14.1% Three Months Ended Twelve Months EndedNine Months Ended

© Core & Main All Rights Reserved. Confidential and Proprietary Information. RECONCILIATION OF NON-GAAP MEASURES 21 ($ in Millions) Net Debt Leverage As of October 29, 2023 October 30,2022 Senior ABL Credit Facility due July 2026 - 90 Senior Term Loan due July 2028 1,466 1,481 Total Debt 1,466$ 1,571$ Less: Cash & Cash Equivalents (101) - Net Debt 1,365$ 1,571$ Twelve Months Ended Adjusted EBITDA 914 922 Net Debt Leverage 1.5x 1.7x