Commitments and Contingencies	3 Months Ended
Jun. 30, 2026
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Matters The Company is involved from time to time in various legal proceedings and administrative actions related to the normal conduct of its business, including general liability claims, putative class action lawsuits and litigation concerning its products. Although it is impossible to predict the outcome of any pending legal proceeding, management believes that such proceedings and actions should not, individually or in the aggregate, have a material adverse effect on the Company’s condensed consolidated financial position, results of operations or cash flows, except as described in these condensed consolidated financial statements. Australia Class Action Securities Claim On May 8, 2023, a group proceeding (class action) was filed in The Supreme Court of Victoria, Australia by Raeken Pty Ltd against James Hardie Industries plc on behalf of persons who purchased certain James Hardie equity securities from February 7, 2022 through November 7, 2022. The litigation is being funded by a litigation funder in Australia, CASL Funder Pty Ltd. The proceeding includes allegations that James Hardie breached relevant provisions of the Corporations Act 2001 (Cth) and the Australian Securities and Investment Commissions Act 2001 (Cth), including with respect to certain forward-looking statements James Hardie made about forecasted financial performance measures during the period specified above. The Company believes the challenged statements were proper and is defending the matter. On July 10, 2026, with consent of the Company, the plaintiffs filed their substitute statement of claim. The trial date remains set for February 15, 2027. The Company is actively defending the matter. As of June 30, 2026, the Company has not recorded a reserve related to this matter as the Company believes the chance of loss is not probable and the amount of loss, if any, cannot be reasonably estimated. On April 6, 2026, a group proceeding (class action) was filed in The Supreme Court of Victoria, Australia by Alexander W. Garton, an individual, against James Hardie Industries plc on his own and on behalf of persons who purchased certain James Hardie equity securities from May 21, 2025 to August 19, 2025. The proceeding includes allegations that James Hardie breached relevant provisions of the Corporations Act 2001 (Cth), the Australian Securities and Investment Commissions Act 2001 (Cth), and Australian Consumer Law, including that James Hardie misled investors and breached continuous disclosure obligations by failing to disclose material issues in its North American Fiber Cement segment and by maintaining its full year FY26 guidance until August 20, 2025. The Company believes its disclosures and the challenged statements were proper and is defending the matter. Currently, the Company is awaiting scheduling of a case management conference and issuance of a case schedule by the Court. The Company is actively defending the matter. As of June 30, 2026, the Company has not recorded a reserve related to this matter as the Company believes the chance of loss is not probable and the amount of loss, if any, cannot be reasonably estimated. U.S. Class Action Securities Claims On October 24, 2025, a putative shareholder class action was filed in the United States District Court for the Northern District of Illinois against James Hardie Industries plc and its CEO and then-CFO on behalf of persons who purchased or otherwise acquired James Hardie common stock between May 20, 2025, through August 18, 2025. The case asserts claims for violations of Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, alleging that the Defendants made material misstatements and omissions throughout the class period related to the strength of the Company’s North America Fiber Cement segment despite alleged customer inventory destocking. On February 17, 2026, the Court appointed Oklahoma Firefighters Pension and Retirement System as lead plaintiff, and an amended complaint was filed on April 20, 2026. On June 22, 2026, the Company filed its motion to dismiss the complaint, and briefing on this motion is scheduled to be completed by October 5, 2026. During February and March 2026, shareholders filed two additional putative class actions in the Circuit Court of Cook County, Illinois and a third shareholder filed a putative class action in the Supreme Court of the State of New York, County of New York against James Hardie Industries plc and certain of its current and former directors and officers on behalf of former AZEK stockholders who received James Hardie common stock in exchange for shares of AZEK common stock in connection with the acquisition of AZEK (collectively, the “State Court Securities Actions”). One of the Illinois cases also named Ernst & Young LLP as a defendant. The State Court Securities Actions assert claims for violations of Sections 11, 12(a)(2) and 15 of the Securities Act of 1933, alleging that defendants made material misstatements and omissions regarding the strength of operations and customer inventory destocking in filings made in connection with James Hardie’s acquisition of AZEK. The Illinois actions were consolidated into a single action on April 20, 2026, and on May 12, 2026, the New York action was voluntarily discontinued. On June 26, 2026, Plaintiffs in the consolidated Illinois action filed the consolidated complaint. The Company is preparing and will file in due course its motion to dismiss in response. The Company believes the U.S. securities claims are without merit and is vigorously defending against them. As of June 30, 2026, the Company has not recorded a reserve related to these matters as the Company believes a loss is not probable and the amount of loss, if any, cannot be reasonably estimated. Environmental The operations of the Company, like those of other companies engaged in similar businesses, are subject to a number of laws and regulations on air, soil and water quality, waste handling and disposal. The Company’s policy is to accrue for environmental costs when it is determined that it is probable that an obligation exists and the amount can be reasonably estimated.

Although it is impossible to predict the outcome of any pending legal proceeding, management believes that such proceedings and actions should not, individually or in the aggregate, have a material adverse effect on the Company’s condensed consolidated financial position, results of operations or cash flows, except as described in these condensed consolidated financial statements.

On May 8, 2023, a group proceeding (class action) was filed in The Supreme Court of Victoria, Australia by Raeken Pty Ltd against James Hardie Industries plc on behalf of persons who purchased certain James Hardie equity securities from February 7, 2022 through November 7, 2022. The litigation is being funded by a litigation funder in Australia, CASL Funder Pty Ltd. The proceeding includes allegations that James Hardie breached relevant provisions of the Corporations Act 2001 (Cth) and the Australian Securities and Investment Commissions Act 2001 (Cth), including with respect to certain forward-looking statements James Hardie made about forecasted financial performance measures during the period specified above. The Company believes the challenged statements were proper and is defending the matter. On July 10, 2026, with consent of the Company, the plaintiffs filed their substitute statement of claim. The trial date remains set for February 15, 2027. The Company is actively defending the matter. As of June 30, 2026, the Company has not recorded a reserve related to this matter as the Company believes the chance of loss is not probable and the amount of loss, if any, cannot be reasonably estimated.

On April 6, 2026, a group proceeding (class action) was filed in The Supreme Court of Victoria, Australia by Alexander W. Garton, an individual, against James Hardie Industries plc on his own and on behalf of persons who purchased certain James Hardie equity securities from May 21, 2025 to August 19, 2025. The proceeding includes allegations that James Hardie breached relevant provisions of the Corporations Act 2001 (Cth), the Australian Securities and Investment Commissions Act 2001 (Cth), and Australian Consumer Law, including that James Hardie misled investors and breached continuous disclosure obligations by failing to disclose material issues in its North American Fiber Cement segment and by maintaining its full year FY26 guidance until August 20, 2025. The Company believes its disclosures and the challenged statements were proper and is defending the matter. Currently, the Company is awaiting scheduling of a case management conference and issuance of a case schedule by the Court. The Company is actively defending the matter. As of June 30, 2026, the Company has not recorded a reserve

On October 24, 2025, a putative shareholder class action was filed in the United States District Court for the Northern District of Illinois against James Hardie Industries plc and its CEO and then-CFO on behalf of persons who purchased or otherwise acquired James Hardie common stock between May 20, 2025, through August 18, 2025. The case asserts claims for violations of Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, alleging that the Defendants made material misstatements and omissions throughout the class period related to the strength of the Company’s North America Fiber Cement segment despite alleged customer inventory destocking. On February 17, 2026, the Court appointed Oklahoma Firefighters Pension and Retirement System as lead plaintiff, and an amended complaint was filed on April 20, 2026. On June 22, 2026, the Company filed its motion to dismiss the complaint, and briefing on this motion is scheduled to be completed by October 5, 2026.

During February and March 2026, shareholders filed two additional putative class actions in the Circuit Court of Cook County, Illinois and a third shareholder filed a putative class action in the Supreme Court of the State of New York, County of New York against James Hardie Industries plc and certain of its current and former directors and officers on behalf of former AZEK stockholders who received James Hardie common stock in exchange for shares of AZEK common stock in connection with the acquisition of AZEK (collectively, the “State Court Securities Actions”). One of the Illinois cases also named Ernst & Young LLP as a defendant. The State Court Securities Actions assert claims for violations of Sections 11, 12(a)(2) and 15 of the Securities Act of 1933, alleging that defendants made material misstatements and omissions regarding the strength of operations and customer inventory destocking in filings made in connection with James Hardie’s acquisition of AZEK. The Illinois actions were consolidated into a single action on April 20, 2026, and on May 12, 2026, the New York action was voluntarily discontinued. On June 26, 2026, Plaintiffs in the consolidated Illinois action filed the consolidated complaint. The Company is preparing and will file in due course its motion to dismiss in response.

The Company believes the U.S. securities claims are without merit and is vigorously defending against them. As of June 30, 2026, the Company has not recorded a reserve related to these matters as the Company believes a loss is not probable and the amount of loss, if any, cannot be reasonably estimated.

The operations of the Company, like those of other companies engaged in similar businesses, are subject to a number of laws and regulations on air, soil and water quality, waste handling and disposal. The Company’s policy is to accrue for environmental costs when it is determined that it is probable that an obligation exists and the amount can be reasonably estimated.