SUBSEQUENT EVENTS	6 Months Ended
Mar. 27, 2026
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	19. SUBSEQUENT EVENTS On April 7, 2026, the Company completed the sale of its HDPE business, which had been classified as held for sale as of March 27, 2026. See Note 4, “Assets Held for Sale” for additional details. On April 28, 2026, the Company entered into settlement agreements (the "Settlement Agreements") with two of the three putative classes in a case captioned In re PVC Pipe Antitrust Litigation (“Class Action Litigation”). These two classes were the Direct Purchaser Plaintiffs ("DPP Plaintiffs") and the Non-Converter Seller Purchaser Plaintiffs ("NCSP" Plaintiffs) (together, the "DPP and NCSP Plaintiffs"), individually and on behalf of the putative DPP and NCSP Plaintiff class members. The Settlement Agreements totaled $136.5 million and was recognized in the Company’s financial statements for the quarter ended March 27, 2026. On April 30, 2026, Atkore’s Board of Directors approved a quarterly dividend payment of $0.33 per share of common stock payable on May 29, 2026 to stockholders of record on May 19, 2026. On April 30, 2026, the Company completed the sale of its Vergo Coating SRL and Vergo Galva NV businesses in Belgium. These businesses did not meet the criteria to be classified as assets held for sale as of March 27, 2026.

SUBSEQUENT EVENTS

6 Months Ended

Mar. 27, 2026

19. SUBSEQUENT EVENTS

On April 7, 2026, the Company completed the sale of its HDPE business, which had been classified as held for sale as of March 27, 2026. See Note 4, “Assets Held for Sale” for additional details.

On April 28, 2026, the Company entered into settlement agreements (the "Settlement Agreements") with two of the three putative classes in a case captioned In re PVC Pipe Antitrust Litigation (“Class Action Litigation”). These two classes were the Direct Purchaser Plaintiffs ("DPP Plaintiffs") and the Non-Converter Seller Purchaser Plaintiffs ("NCSP" Plaintiffs) (together, the "DPP and NCSP Plaintiffs"), individually and on behalf of the putative DPP and NCSP Plaintiff class members. The Settlement Agreements totaled $136.5 million and was recognized in the Company’s financial statements for the quarter ended March 27, 2026.

On April 30, 2026, Atkore’s Board of Directors approved a quarterly dividend payment of $0.33 per share of common stock payable on May 29, 2026 to stockholders of record on May 19, 2026.

On April 30, 2026, the Company completed the sale of its Vergo Coating SRL and Vergo Galva NV businesses in Belgium. These businesses did not meet the criteria to be classified as assets held for sale as of March 27, 2026.