Spruce (Sitka)
Exceptional stiffness for its very low weight, which is why it is used for aircraft structures and instrument soundboards. A structural softwood with an unusually high strength-to-weight ratio.
Properties
- Family
- Wood
- Category
- wood
- Species
- Picea sitchensis
- Density
- 0.43 g/cm³ · 430 kg/m³
Densityhow spruce (sitka) compares
Wood propertiesUSDA clear-wood values at 12% moisture content
- Species measured
- Sitka spruce (Picea sitchensis)
- Specific gravity
- 0.4
- Janka side hardness
- 510 lbf · 2,269 N
- Modulus of rupture
- 10,200 psi · 70.3 MPa
- Modulus of elasticity
- 1.57 ×10⁶ psi · 10.82 GPa
- Shrinkage, green to oven-dry
- 4.3% radial · 7.5% tangential · 11.5% volumetric
Source: USDA Forest Service, Wood Handbook — Wood as an Engineering Material (FPL-GTR-190, 2010), Table 5–3b, for clear straight-grained specimens at 12% moisture content. The grey figures are converted at 1 lbf = 4.448 N, 1 psi = 6.895 kPa and 1 GPa = 145,038 psi; the inch-pound numbers are the published ones. Specific gravity is oven-dry mass over volume at 12% moisture content, so it sits about 12% below the working density at the top of this page (0.4 × 1.12 ≈ 0.45 g/cm³). The two come from different sampling programmes, so a few species differ by more than that.
Applicationswhere spruce (sitka) is normally specified
Appearance & workabilitytrade experience, not measured values
- Origin
- Pacific coast of North America
- Appearance
- Creamy white to pale yellow, straight grain with a fine texture
- Working
- High stiffness for its weight — the reason it is a soundboard and spar wood. The surface is soft and dents easily.
Unlike the USDA figures above, these lines are not measurements: they carry no units and no single source. They describe how the timber is generally found to behave rather than what it is guaranteed to do — read them as the consensus of the trade, not as a specification.
Practical notes
- Density is for air-dried stock at about 12% moisture content
- Best strength-to-weight of the common softwoods
- Poor decay resistance — protect from moisture
Lumber sizeswhat spruce (sitka) weighs in each nominal size
Lumber size databaseDressed sizes are the same for every species — a 2x4 is 1-1/2 x 3-1/2 in in oak as much as in spruce. What changes is the weight, and that is derived here from spruce (sitka)'s density of 0.43 g/cm³.
Tools used on itmatched on the wood family, not on this page
All toolsWhich tools work a material is a property of the family (Wood), not of the individual species — so this list is the same on every wood page, and changes when the tool data changes rather than when this paragraph does.
Frequently asked questionsthe questions this page answers about Spruce (Sitka)
How hard is Spruce (Sitka)?
Janka hardness is 510 lbf — the force needed to push a steel ball halfway into the wood. Higher is harder; this is the number quoted when a wood is specified for floors, worktops or butcher blocks.
How dense is Spruce (Sitka)?
Density is 0.43 g/cm³, and the USDA table gives a specific gravity of 0.4.
How much does Spruce (Sitka) move when it dries?
Green to oven-dry it shrinks 11.5% by volume — 4.3% radially and 7.5% tangentially. Movement across the grain is what opens joints, so a species that moves a lot wants room to move.
What is Spruce (Sitka) used for?
Typical uses are Aircraft structures, Instrument soundboards, Masts and Spars.
How does Spruce (Sitka) work with hand and machine tools?
High stiffness for its weight — the reason it is a soundboard and spar wood. The surface is soft and dents easily.