GRIFFON CORP

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): August 10, 2026

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

On August 10, 2026, Griffon Corporation (the “Company”) entered into a Purchase Agreement (the “Purchase Agreement”) pursuant to which the Company agreed to issue and sell to the several initial purchasers named therein (the “Initial Purchasers”) $800 million aggregate principal amount of the Company’s 6.25% senior notes due 2034 (the “Notes”). The Purchase Agreement includes the terms and conditions of the offer and sale of the Notes, indemnification and contribution obligations and other terms and conditions customary in agreements of this type. A copy of the Purchase Agreement is filed herewith as Exhibit 99.1. The foregoing description of the Purchase Agreement does not purport to be complete and is qualified in its entirety by reference to the Purchase Agreement.

On August 10, 2026, the Company issued a press release announcing the pricing of the Notes. A copy of the press release is attached hereto as Exhibit 99.2 and is incorporated herein by reference.

(d)Exhibits

99.1*Purchase Agreement, dated as of August 10, 2026, by and among Griffon Corporation, the Guarantors named therein and BofA Securities, Inc., as Representative of the several Initial Purchasers named therein.

99.2 Press Release, dated August 10, 2026, regarding the Pricing of the Notes.

*A portion of the exhibit has been omitted pursuant to Item 601(b)(10)(iv) of Regulation S-K because it is of the type of information (i) that is not material to investors and (ii) that the registrant treats as private or confidential.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Exhibit Index

99.1 Purchase Agreement, dated as of August 10, 2026, by and among Griffon Corporation, the Guarantors named therein and BofA Securities, Inc., as Representative of the several Initial Purchasers named therein.

99.2 Press Release, dated August 10, 2026, regarding the Pricing of the Notes.