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The following description of the SiteOne Savings and Investment Plan (“the Plan”) provides only general information. Participants should refer to the Plan document for a more complete description of the Plan’s provisions.

General

The Plan is a defined contribution plan under Section 401(k) of the Internal Revenue Code covering substantially all employees of SiteOne Landscape Supply, Inc. and its subsidiaries (“the Company”), except for collective bargaining employees, leased employees, non-resident aliens with no U.S. source income, and seasonal employees. The administrator of the Plan (the “Plan Administrator”) is the Company’s Benefits Committee. The Plan is subject to the provisions of the Employee Retirement Income Security Act of 1974, as amended (“ERISA”).

From time to time, the Company enters into strategic acquisitions in an effort to better service existing customers and to attract new customers. The Company’s policy is to have the seller terminate any benefit plans that they had in place prior to or concurrent with the sale. Any onboarded employees are offered participation in the Plan in accordance with the Plan’s eligibility provisions.

On December 23, 2022, Congress passed the Consolidated Appropriations Act of 2023 which included SECURE Act 2.0. SECURE Act 2.0 contains approximately 90 retirement provisions, with varying effective dates through 2027. Since SECURE Act 2.0 provisions include both required and optional elements, the Plan Administrator has determined the optional provisions it plans to elect and expects to amend the Plan document accordingly by December 31, 2026.

Contributions

Eligible employees are automatically enrolled into the Plan after 30 days of employment unless the employee elects otherwise. Pre-tax contributions are withheld at 3% of eligible compensation and increased by 1% each year until they reach 50% of eligible compensation unless the employee elects differently. Each year, participants may make pre-tax or Roth after-tax contributions up to 50% of eligible compensation, as defined by the Plan document, not to exceed a maximum of $23,500 for the Plan year. Participants who have attained age 50 before the end of the Plan year are eligible to make catch-up contributions of up to $7,500 for the Plan year. Participants age 60 through 63 have an increased “super” catch up limit that is the greater of $10,000 (indexed) or 150% of the regular catch-up contribution limit. Participants may also contribute amounts representing distributions from other qualified defined benefit or defined contribution plans. The Company may make discretionary matching contributions. For the year ended December 31, 2025, the Company made matching contributions equal to 120% of the first 2% of the participant’s eligible compensation plus 40% of the next 4% of the participant’s eligible compensation.

Participant Accounts

Each participant’s account is credited with the participant’s contributions and any Company matching contributions as well as allocations of Plan earnings and losses and charged with certain administrative expenses. The benefit to which a participant is entitled is the benefit that can be provided from the participant’s vested account. Participants direct the investment of their contributions into various investment options offered by the Plan. The Plan currently offers mutual funds, a Company Stock Fund, a money market fund, self-directed brokerage accounts, and collective investment trust funds as investment options for participants.

Vesting

Participants are vested immediately in their voluntary contributions plus actual earnings and losses thereon. A participant is 100% vested in employer matching contributions after three years of credited service if employed after December 23, 2013. If employed prior to that date, a participant is always 100% vested in the employer matching contribution. Certain matching contributions from prior employers of merged plans are subject to vesting schedules in place at the time of the merger.

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The framework for measuring fair value provides a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (level 1 measurements) and the lowest priority to unobservable inputs (level 3 measurements). The three levels of the fair value hierarchy under the Financial Accounting Standards Board Accounting Standards Codification 820, Fair Value Measurement (“FASB ASC 820”) are described as follows:

Level 1: Inputs to the valuation methodology are unadjusted quoted prices for identical assets or liabilities in active markets.

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Although it has not expressed any intent to do so, the Company has the right under the Plan to discontinue its contributions at any time and to terminate the Plan subject to the provisions of ERISA. In the event of Plan termination, participants would become fully vested in their Company contributions. The Plan’s assets would be distributable to the participants in accordance with the respective values of their accounts.

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The Company has adopted a pre-approved Plan document, which has received a determination letter dated June 30, 2020, that the Plan document is designed in accordance with applicable sections of the Internal Revenue Code (“IRC”). The Plan Administrator and the Plan’s management believe that the Plan, as restated, is designed and is currently being operated in compliance with the applicable requirements of the IRC and therefore believe the Plan is qualified and the related trust is tax-exempt.

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The Plan invests in various investments. Investments are exposed to various risks such as interest rate, market, and credit volatility. Market risks include U.S. and global events that could impact the value of Plan investments. Due to the level of risk associated with certain investments, it is at least reasonably possible that changes in the values of investments will occur in the near term and that such changes could materially affect participants’ account balances and the amounts reported in the statements of net assets available for benefits.

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The Plan held 32,145 and 31,790 shares of Company common stock valued at $4,006,292 and $4,191,157 at December 31, 2025 and 2024, respectively. There were no dividends declared on the Company common stock during 2025.

Plan investments include shares of mutual funds, a money market fund, self-directed brokerage accounts, and a collective investment trust fund managed by Fidelity. Fidelity is the trustee and recordkeeper for the Plan; therefore, transactions in these investments qualify as party-in-interest transactions. Fees incurred by the Plan for investment management services are included in net appreciation in fair value of investments, as they are paid through revenue sharing rather than a direct payment.

SiteOne Savings and Investment Plan

Schedule H, Part IV, Line 4i - Schedule of Assets (Held at End of Year)

December 31, 2025

Plan #: 002

EIN: 36-4485550