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4" x 4" #2 & Better Kiln-Dried Fir Dimensional Lumber, KDHT S4S
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4" x 4" #2 & Better Kiln-Dried Fir Lumber (KDHT, S4S)
Kiln-dried, heat-treated (KDHT) fir 4x4, graded #2 & Better and surfaced on four sides (S4S) to an actual 3-1/2 in. x 3-1/2 in. Stocked in 8, 10 and 12 ft. lengths.
Dry stock holds its size better than green lumber, which suits posts, framing and bracing where shrinkage matters. #2 & Better is a structural grade, not an appearance grade. Expect knots and natural character.
Features and Common Uses
- Kiln-dried and heat-treated (KDHT) for lower moisture content than green stock
- Surfaced on four sides (S4S) for uniform 3-1/2 in. x 3-1/2 in. dimensions
- #2 & Better structural grade fir
- Three stocked lengths: 8, 10 and 12 ft.
Commonly used for:
- Posts for decks, fences and pergolas (use pressure-treated stock for ground contact)
- Interior structural framing, including single- and multi-family homes and additions
- Barns, sheds, and commercial and industrial construction
- Bracing and concrete forming
Specifications
| Species | Fir |
|---|---|
| Grade | #2 & Better |
| Drying | Kiln-dried, heat-treated (KDHT) |
| Surfacing | S4S (surfaced four sides) |
| Nominal size | 4 in. x 4 in. |
| Actual size (T x W) | 3-1/2 in. x 3-1/2 in. (89 mm x 89 mm) |
| Available lengths | 8 ft., 10 ft., 12 ft. |
Actual 4x4 dimensions are 3-1/2 in. x 3-1/2 in. (89 x 89 mm). Dry (S-Dry) lumber has a moisture content of 19 percent or less. Source: Lumber 4x4 actual dimensions, dimensions.com.
Frequently Asked Questions
What is the actual size of a 4x4?
3-1/2 in. x 3-1/2 in. (89 mm x 89 mm). The 4x4 name is the nominal size.
What does KDHT mean?
Kiln-dried, heat-treated. The lumber has been dried in a kiln, so it carries less moisture than green stock.
Can I use this in the ground or on a deck exposed to the weather?
Untreated fir is not rated for ground contact. For buried posts, choose pressure-treated lumber.
Is #2 & Better an appearance grade?
No. It is a structural grade, and knots and other natural characteristics are allowed.
See our grading guide for what each grade allows: Source: Dimensional lumber grading guide (PDF).