BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)

12 Months Ended

Sep. 30, 2025

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Presentation

Basis of Presentation — The accompanying audited consolidated financial statements of the Company and all of its subsidiaries included herein have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”).

The audited consolidated financial statements include the assets and liabilities used in operating the Company's business. All intercompany balances and transactions have been eliminated in consolidation. The results of companies acquired or disposed of are included in the audited consolidated financial statements from the effective date of acquisition or up to the date of disposal.

Fiscal Periods

Fiscal Periods — The Company has a fiscal year that ends on September 30. The Company's fiscal quarters typically end on the last Friday in December, March and June as it follows a 4-5-4 calendar.

Use of Estimates

Use of Estimates — The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclose contingent assets and liabilities at the date of the consolidated financial statements and report the associated amounts of revenues and expenses. Actual results could differ materially from these estimates.

Revenue Recognition

Revenue Recognition — The Company’s revenue arrangements primarily consist of a single performance obligation to transfer promised goods which is satisfied at a point in time when title, risks and rewards of ownership, and subsequently control have transferred to the customer. This generally occurs when the product is shipped to the customer, with an immaterial amount of transactions in which control transfers upon delivery. The Company primarily offers assurance-type standard warranties that do not represent separate performance obligations.

Under the Inflation Reduction Act of 2022 (“IRA”), the Company is eligible for tax credits related to the manufacturing and selling of components used in the solar energy industry. These tax credits are transferable under the IRA when they meet certain criteria. When credits do not meet the transferability criteria, the benefit is recognized within income tax expense in accordance with ASC 740, “Income Taxes.” Beginning in fiscal 2024, the Company has concluded that the credits generated are transferable. As such, the benefit of the solar energy tax credits is recognized as a reduction of cost of sales.

The Company has contractual arrangements with certain customers to transfer a portion of the tax credits or to otherwise provide a rebate based on an agreed-upon value of the tax credits generated. Pursuant to such contractual arrangements, if the tax credits will be transferred to the customer, the Company identifies two separate performance obligations: (1) transfer of the promised goods; and (2) transfer of the defined portion of the tax credits earned. The Company allocates the total value of these transactions between the two performance obligations. As a result of this allocation, the Company recognizes a reduction to revenue, similar to a rebate. For arrangements with no transfer of tax credits there is only a single performance obligation to transfer the promised goods and a rebate, which is recognized as a reduction of revenue, is granted based on the agreed-upon value of the tax credits generated.

The solar energy tax credit receivable is recorded in Prepaid Expenses and Other Current Assets and the liability to transfer the defined portion of the tax credits or the economic value is recorded in Customer Liabilities.

For the year ended September 30, 2025, the Company has recognized a reduction of revenue of $52,989 for the economic value of tax credits to be transferred and a benefit to cost of sales of $58,369. As of September 30, 2025, the Company has a liability of $12,985 for credits to be transferred or the value thereof. As of September 30, 2025, all activity related to the solar energy tax credits is within the Safety & Infrastructure segment.

The Company has certain arrangements that require it to estimate at the time of sale the amounts of variable consideration that should not be recorded as revenue as certain amounts are not expected to be collected from customers, as well as an estimate of the value of products to be returned. The Company principally relies on historical experience, specific customer agreements, and anticipated future trends to estimate these amounts at the time of sale and to reduce the transaction price. These arrangements include sales discounts and allowances, volume rebates, and returned goods. The Company records its obligations related to these items within the Customer Liabilities line on the balance sheet.

To the extent that the Company receives cash payments for performance obligations that have not yet been met, the Company records these amounts as deferred revenue within the Customer Liabilities line on the balance sheet.

The Company has elected to utilize certain practical expedients available under GAAP. The Company records amounts billed to customers for reimbursement of shipping and handling costs within revenue. Shipping and handling costs associated with outbound freight after control over a product has transferred to a customer are accounted for as fulfillment costs and are included in cost of sales. Sales taxes and other usage-based taxes are excluded from revenue. The practical expedient not to disclose information about remaining performance obligations has also been elected as these obligations have an original duration of one year or less. The Company does not evaluate whether the

selling price includes a financing interest component for contracts that are less than a year. The Company also expenses costs incurred to obtain a contract, primarily sales commissions, as all obligations will be settled in less than one year.

The Company typically receives payment 30 to 60 days from the point it has satisfied the related performance obligation.

Cost of Sales

Cost of Sales — The Company includes all costs directly related to the production of goods for sale in cost of sales in the statement of operations. These costs include direct material, direct labor, production related overheads, excess and obsolescence costs, lower of cost or market provisions, freight costs, and the depreciation and amortization of assets directly used in the production of goods for sale.

Selling, General and Administrative Expenses

Selling, General and Administrative Expenses — These amounts primarily include payroll-related expenses for both administrative and selling personnel, compensation expense from stock-based awards, restructuring-related charges, third-party professional services and transactional gains or losses for foreign currency transactions, excluding the foreign exchange exposure for intercompany loan transactions, which is included in Other expense, net.

Cash and Cash Equivalents

Cash and Cash Equivalents — The Company considers all highly liquid investments with a maturity of three months or less, when purchased, to be cash equivalents.

Accounts Receivable and Allowance for Doubtful Accounts

Accounts Receivable and Allowance for current and expected credit losses — The Company carries its accounts receivable at their face amounts less an allowance for current and expected credit losses. The allowance for current and expected credit losses reflects the best estimate of current and expected losses inherent in the Company’s accounts receivable portfolio determined on the basis of historical experience, specific allowances for known troubled accounts and other available evidence.

Inventories

Inventories — Inventories are recorded at the lower of cost (primarily LIFO) or market value. The Company estimates losses for excess and obsolete inventory through an assessment of its net realizable value based on the aging of the inventory and an evaluation of the likelihood of recovering the inventory costs based on anticipated demand and selling price.

Property, Plant and Equipment

Property, Plant and Equipment — Property, plant and equipment, net, is recorded at cost less accumulated depreciation. Maintenance and repair expenditures are charged to expense when incurred. Depreciation is calculated using the straight-line method over the estimated useful lives of the related assets as follows:

Buildings	4 to 40 years
Building improvements	3 to 20 years
Machinery and equipment	1 to 20 years
Leasehold improvements	Lesser of remaining term of the lease or useful life
Software	2 to 10 years

The internal and external costs incurred to develop internal use computer software during the application development stage of the implementation, including the design of the chosen path, are capitalized. Other costs, including expenses incurred during the preliminary project stage, training expenses, data conversion costs and expenses incurred in the post implementation stage are expensed in the period incurred. Capitalized costs are amortized ratably over the useful life of the software when the software becomes operational. Upgrades and enhancements to internal use software are capitalized only if the costs result in additional functionality. The Company does not plan to sell or market its internal use computer software to third parties.

Business Combinations

Business Combinations — The Company accounts for business combinations using the acquisition method of accounting, which requires that once control is obtained, all the assets acquired and liabilities assumed, including amounts attributable to noncontrolling interests, are recorded at their

respective fair values at the date of acquisition. The determination of fair values of identifiable assets and liabilities requires estimates and the use of valuation techniques when market value is not readily available. For intangible assets acquired in a business combination, the Company typically use the income method. Significant estimates in valuing certain intangible assets include, but are not limited to, the amount and timing of future cash flows, growth rates, discount rates and useful lives. The excess of the purchase price over fair values of identifiable assets and liabilities is recorded as goodwill

Long-Lived Asset and Finite - Lived Intangible Asset Impairments

Long-Lived Asset and Finite - Lived Intangible Asset Impairments — The Company reviews long-lived assets, including property, plant and equipment and finite-lived intangible assets for impairment whenever events or changes in business circumstances indicate that the carrying amount of the asset may not be fully recoverable.

The Company groups assets at the lowest level for which cash flows are separately identified in order to measure an impairment. Recoverability of an asset or asset group is first measured by a comparison of the carrying amount to its estimated undiscounted future cash flows expected to be generated by the asset or asset group. If the carrying amount exceeds its estimated undiscounted future cash flows, an impairment charge is recognized as the amount by which the carrying amount of the asset or asset group exceeds the estimated fair value. If impairment is determined to exist, any related impairment loss is calculated based on the estimated fair value. Impairment losses on assets to be disposed of or held for sale, if any, are based on the estimated proceeds to be received, less costs of disposal.

The Company also considers potential impairment indicators associated with other finite-lived intangible assets, including its customer relationships, patents, and non-compete agreements. An impairment is recognized if the carrying value of an asset or asset group exceeds the estimated undiscounted future cash flows expected to result from the use of the asset or asset group and its eventual disposition. The Company's key customers are primarily wholesale and national distributors. The terms of these relationships are based on purchase orders and are not contractually based. Customer relationships are amortized on a straight-line basis over their useful lives, ranging from 6 to 14 years. The Company evaluates the appropriateness of remaining useful lives based on customer attrition rates. Other intangible assets are amortized on a straight-lined basis over their estimated useful lives, ranging from 1 to 20 years.

Goodwill and Indefinite-Lived Intangible Assets Impairments

Goodwill and Indefinite-Lived Intangible Asset Impairments — The Company assesses the recoverability of goodwill and indefinite-lived trade names on an annual basis in accordance with Accounting Standards Codification (“ASC”) 350 “Intangibles - Goodwill and Other.” The measurement date is the first day of the fourth fiscal quarter, or more frequently, if events or circumstances indicate that it is more likely than not that the fair value of a reporting unit or the respective indefinite-lived trade name is less than the carrying value. The Company can elect to perform a quantitative or qualitative test of impairment.

For fiscal 2025, 2024, and 2023, the Company performed a quantitative impairment assessment for goodwill. The Company calculated the fair value of its six reporting units considering three valuation approaches: (a) the income approach; (b) the guideline public company method; and (c) the comparable transaction method. The income approach calculates the fair value of the reporting unit using a discounted cash flow approach. Internally forecasted future cash flows, which the Company believes reasonably approximate market participant assumptions, are discounted using a weighted average cost of capital (Discount Rate) developed for each reporting unit. The Discount Rate is developed using market observable inputs, as well as considering whether or not there is a measure of risk related to the specific reporting unit’s forecasted performance. The key uncertainties in these calculations are the assumptions used in determining the reporting unit’s forecasted future performance, including revenue growth and EBITDA margins, as well as the perceived risk associated with those forecasts. Fair value under the guideline public company method is determined for each reporting unit by applying market multiples for comparable public companies to the reporting unit’s financial results. Fair value under the comparable transaction method is determined based on exchange prices in actual transactions and on asking prices for controlling interests in public or private

companies currently offered for sale by applying market multiples for comparable public companies to the unit’s financial results. The key uncertainties in the guideline public company method and the comparable transaction method calculations are the assumptions used in determining the reporting unit's comparable public companies, comparable transactions and the selection of the market multiples.  

As a result of the Company’s plans to exit its operations in Russia and expectation to sell the related business at a loss, the Company recognized a goodwill impairment of $1,721 in fiscal 2023 that was allocated from the reporting unit on a relative fair value basis. As a result of annual goodwill impairment testing performed in fiscal 2025, it was determined that the goodwill of the Mechanical reporting unit was impaired as the reporting unit’s book value exceeded its fair value. The Company recorded a goodwill impairment on the Mechanical reporting unit of $18,885. See Note 13, “Goodwill and Intangible Assets.” The Company did not record any goodwill impairments in fiscal 2024.

As noted above, ASC 350 also requires that the Company test the indefinite-lived intangible assets for impairment at least annually. Under ASC 350, if the carrying value of the indefinite-lived asset is higher than its fair value, then the asset is deemed to be impaired and the impairment charge is estimated as the excess carrying value over the fair value. The Company calculated the fair value of its indefinite-lived intangible assets using the income approach, specifically the relief-from-royalty method. The relief-from-royalty method is used to estimate the cost savings that accrue to the owner of an intangible asset who would otherwise have to pay royalties or license fees on revenues earned through the use of the asset. Internally forecasted revenues, which the Company believes reasonably approximate market participant assumptions, are multiplied by a royalty rate to arrive at the estimated net after tax cost savings. The royalty rate used in the analysis is based on an analysis of empirical, market-derived royalty rates for guideline intangible assets. The net after tax cost savings are discounted using the Discount Rate. The Discount Rate is developed using market observable inputs, as well as considering whether or not there is a measure of risk related to the specific indefinite lived intangible assets' forecasted performance. The key uncertainties in these calculations are the assumptions used in determining the revenue associated with each indefinite-lived intangible asset and the royalty rate.

Fair Value Measurements

Fair Value Measurements — Authoritative guidance for fair value measurements establishes a three-level hierarchy that ranks the quality and reliability of information used in developing fair value estimates. The hierarchy gives the highest priority to quoted prices in active markets and the lowest priority to unobservable data. In cases where two or more levels of inputs are used to determine fair value, a financial instrument's level is determined based on the lowest level input that is considered significant to the fair value measurement in its entirety. The three levels of the fair value hierarchy are summarized as follows:

Level 1-inputs are based upon quoted prices (unadjusted) in active markets for identical assets or liabilities which are accessible as of the measurement date.

Level 2-inputs are based upon quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, and model-derived valuations for the asset or liability that are derived principally from or corroborated by market data for which the primary inputs are observable, including forward interest rates, yield curves, credit risk and exchange rates.

Level 3-inputs for the valuations are unobservable and are based on management's estimates of assumptions that market participants would use in pricing the asset or liability. The fair values are therefore determined using model-based techniques such as option pricing models and discounted cash flow models.

Income Taxes and Uncertain Tax Positions

Income Taxes and Uncertain Tax Positions — The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements. Under this method, deferred tax assets and liabilities are determined based on the

differences between the financial reporting and tax basis of assets and liabilities using enacted tax rates in effect for the year it is expected the differences will reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period of the enactment date.

The Company periodically assesses the realizability of the deferred tax assets. In making this determination management considers all available evidence, both positive and negative, including earnings history, expectations of future taxable income and available tax planning strategies. A valuation allowance is recorded to reduce the Company’s deferred tax assets to the amount that is considered more likely than not to be realized. Changes in the required valuation allowance are recorded in income in the period such determination is made.

Certain tax positions may be considered uncertain requiring an assessment of whether an allowance should be recorded. Provisions for uncertain tax positions provide a recognition threshold based on an estimate of whether it is more likely than not that a position will be sustained upon examination. The Company measures its uncertain tax positions as the largest amount of benefit that is greater than a 50% likelihood of being realized upon examination. Interest and penalties related to unrecognized tax benefits are recorded as a component of income tax expense.

Leases

Leases — Starting in fiscal 2020, as a result of the adoption of ASC 842 “Leases,” the Company recognizes if an arrangement is a lease at the inception of the contract. The Company determines which party has the right to control an asset during the contract term and recognizes a Right of Use (“ROU”) asset and lease obligations based on the present value of the future minimum lease payments over the term of the lease.

The Company engages in leasing transactions to meet the needs of the business. The Company leases certain manufacturing facilities, warehouses and distribution centers, office space, forklifts, vehicles and other machinery and equipment. The determination to lease, rather than purchase, an asset is primarily contingent upon capital requirements, duration of the forecasted business investment, and asset availability.

The Company determines if an arrangement is a lease at inception and all arrangements deemed to be leases are subject to an assessment to determine the classification between finance and operating leases. The Company's significant assumptions and judgments in determining whether a contract is or contains a lease include establishing whether the supplier has the ability to use other assets to fulfill its service or whether the terms of the agreement enable the Company to control the use of a dedicated property, plant and equipment asset during the contract term. In the majority of the Company's contracts where it must identify whether a lease is present, it is readily determinable that the Company controls the use of the assets and obtains substantially all of the economic benefit during the term of the contract. In those contracts where identification is not readily determinable, the Company has determined that the supplier has either the ability to use another asset to provide the service or the terms of the contract give the supplier the rights to operate the asset at its discretion during the term of the contract, in which case the arrangement would not constitute a lease.

Right-of-use assets and lease obligations are recognized based on the present value of the future minimum lease payments over the lease term as of the commencement date. The Company’s lease agreements have terms that include both lease and non-lease components. Lease component fees are included in the present value of future minimum lease payments. Conversely, non-lease components are not subject to capitalization and are expensed as incurred. Per ASC 842 “Leases,” the contractual interest rate is used to calculate the present value of the future minimum lease payments. However, the majority of the Company’s leases do not provide an implicit rate. Therefore, the Company's significant assumption and judgments in determining the discount rate include determining the incremental borrowing rate. The Company’s incremental borrowing rates are based on the term of the lease, the economic environment of the lease and the effect of collateralization. The valuation of the ROU asset also includes lease payments made in advance of the lease commencement date and initial direct costs incurred to secure the lease and is reduced for lease incentives. The lease terms include options to extend or terminate the lease when it is reasonably certain the Company will exercise the options. Leases with an initial term of 12 months or less are classified as short-term leases and are not recorded on the consolidated balance sheets. The lease expense for short-term leases is recognized on a straight-line basis over the lease term.

The Company has certain leasing agreements, related to leased vehicles available to our sales personnel, that contain guaranteed residual value terms, which are not expected to be triggered. The Company’s leasing portfolio does not contain any material restrictive covenants.

Translation of Foreign Currency

Translation of Foreign Currency — For the Company's non-U.S. subsidiaries that report in a functional currency other than United States dollars, assets and liabilities are translated into United States dollars using period end exchange rates. Revenue and expenses are translated at the monthly average exchange rates in effect during the reporting period. Foreign currency translation adjustments are included as a component of accumulated other comprehensive loss within the consolidated statements of comprehensive income.

Recent Accounting Pronouncements

Recent Accounting Pronouncements

A summary of recently adopted accounting guidance is as follows. Adoption dates are on the first day of the fiscal year indicated below, unless otherwise specified.

ASU	Description of ASU	Impact to Atkore	Adoption Date
2023-07 Segment Reporting (Topic 280); Improvements to Reportable Segment Disclosures	The ASU requires companies to provide additional segment disclosures including disclosing title and position of the chief operating decision maker (“CODM”), disclosure of significant segment expenses provided to and reviewed by the CODM, and that public entities provide all annual disclosures about a reportable segment’s profit or loss and assets required by Topic 280 in interim periods.	The Company adopted the standard in fiscal 2025, including the required ASU disclosures in the Segment Information Footnote of the fiscal 2025 annual report, and will begin providing these disclosures in quarterly reports starting in fiscal 2026	2025
2023-09 Income Taxes (Topic 740); Improvements to Income Tax Disclosures	The ASU requires companies to provide additional tax disclosures including specific categories in the rate reconciliations and reconciling items that meet a quantitative threshold. Additional disclosures are also required for income tax paid and the disaggregation of domestic and foreign income tax expense.	The Company will adopt the standard in fiscal 2026 and include the disclosures required by the ASU within the Income Tax Footnote of the annual report.	2026
2024-03 Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40)	The ASU requires companies to disclose, in the notes to the financial statements, specified information about certain costs and expenses. The amendments in this update do not change or remove current expense disclosure requirements presented on the face of the income statement. However, the amendments require the disaggregation of certain expense captions into specified categories in the notes to financial statements and inclusion of certain current disclosures in the same tabular format as the other disaggregation requirements in the amendments.	The Company will adopt the standard in fiscal 2028 and include the disclosures required by the ASU within the annual report and quarterly reports beginning in fiscal 2029.	2028
2025-06 Intangibles-Goodwill and Other-Internal-Use Software (Topic 350-40); Targeted Improvements to the Accounting for Internal-Use Software	This ASU requires companies to consider project stages in determining whether a software development cost for internal-use software is capitalized or expensed. The amendment requires an entity to start capitalizing software costs when management has both authorized and committed to funding the software project and when it is probably that the project will be completed and the software will be used to perform the intended function. Additionally, disclosures are required for all capitalized internal-use software costs, regardless of how those costs are presented in the financial statements in accordance with Subtopic 360-10, Property, Plant, and Equipment-Overall.	The Company is still evaluating the future impact of this accounting standard.	2029