6-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of January 2026

Commission File Number: 001-39974

WEST FRASER TIMBER CO. LTD.

(Exact name of Registrant, as specified in its charter)

1500 - 885 West Georgia Street

Vancouver, British Columbia

Canada, V6C 3E8

Tel:(604) 895-2700

(Address and Telephone Number of Registrant’s Principal ExecutiveOffices)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F ☐   Form 40-F ☒

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1): ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): ☐

EXHIBIT INDEX

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, thereunto duly authorized.

EX-99.1

Exhibit 99.1

For Immediate Release

Notice of Fourth Quarter Results Conference Call

VANCOUVER, B.C., January 22, 2026 – West Fraser Timber Co. Ltd. (“West Fraser” or the “Company”) (TSX and NYSE: WFG) will hold an analysts’ conference call to discuss fourth quarter 2025 financial and operating results on Thursday, February 12, 2026 at 7:00 a.m. Pacific Time/10:00 a.m. Eastern Time.

To participate in the call, please dial: 1-888-510-2154 (Toll-free North America) or (437) 900-0527 (Toll number) or connect on the webcast.

Please let the operator know you wish to participate in the West Fraser conference call chaired by Mr. Sean McLaren, President and Chief Executive Officer.

Following management’s discussion of the quarterly results, the analyst community will be invited to ask questions.

The call will be recorded for webcasting purposes and will be available on our website at www.westfraser.com. West Fraser’s fourth quarter 2025 financial and operating results will be released on Wednesday, February 11, 2026.

About West Fraser

West Fraser is a diversified wood products company with more than 50 facilities in Canada, the United States, the United Kingdom, and Europe, which promotes sustainable forest practices in its operations. The Company produces lumber, engineered wood products (OSB, LVL, MDF, plywood, and particleboard), pulp, newsprint, wood chips, and other residuals. West Fraser’s products are used in home construction, repair and remodelling, industrial applications, papers and tissue. For more information about West Fraser, visit: westfraser.com.

ForMore Information

Investor Contact

Robert B. Winslow, CFA

Director, Investor Relations & Corporate Development

Tel. (416) 777-4426

[email protected]

Media Contact

Joyce Wagenaar

Director, Communications

Tel. (604) 817-5539

[email protected]