Company: WFG
Filing Date: 2025-04-22
Form Type: 6-K
Source: 0001628280-25-018887
Chunk: 0

Company: WEST FRASER TIMBER CO., LTD
Filing Date: 2025-04-22
Form: 6-K
Chunk 0
---
### 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 April 2025

#### Commission File Number: 001-39974

#### WEST FRASER TIMBER CO. LTD.
<div align='center'>(Exact name of Registrant, as specified in its charter)</div>

#### 1500 - 885 West Georgia Street

#### Vancouver, British Columbia

#### Canada, V6C 3E8

#### Tel: (604) 895-2700
<div align='center'>(Address and Telephone Number of Registrant's Principal Executive Offices)</div>

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

<div align='center'>Form 20-F ☐ Form 40-F ☒</div>

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): ☐

The information contained in Exhibits 99.1 and 99.2 of this Form 6-K is incorporated by reference into the Registrant’s registration statements on Form S-8: File Nos. 333-257254 and 333-252631.

### EXHIBIT INDEX
| Exhibit 
 99.1    
 99.2    |     | Description                                                                                                        
 Unaudited Condensed Consolidated Financial Statements for the three months ended March 28, 2025 and March 29, 2024 
 Management's Discussion and Analysis for the three months ended March 28, 2025                                     |
|:--------|:----|:-------------------------------------------------------------------------------------------------------------------|
| 99.3    |     | CEO - Certification of Interim Filings                                                                             |
| 99.4    |     | CFO - Certification of Interim Filings                                                                             |
| 99.5    |     | News release dated April 22, 2025 re: West Fraser Announces First Quarter 2025 Results                             |

### SIGN