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Spruce-Pine-Fir (SPF) Softwood

Spruce-pine-fir is a wood-based material. It has the highest tensile strength and a moderately low heat capacity among wood-based materials. The graph bars on the material properties cards below compare spruce-pine-fir to other wood-based materials (top) and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

Mechanical Properties

Compressive (Crushing) Strength

50 MPa 7.3 x 103 psi

Elastic (Young's, Tensile) Modulus

16 GPa 2.3 x 106 psi

Elongation at Break

1.5 %

Poisson's Ratio


Shear Modulus

1.2 GPa 0.17 x 106 psi

Tensile Strength: Ultimate (UTS)

85 MPa 12 x 103 psi

Thermal Properties

Maximum Temperature: Mechanical

130 °C 270 °F

Specific Heat Capacity

1380 J/kg-K 0.33 BTU/lb-°F

Thermal Conductivity

0.12 W/m-K 0.069 BTU/h-ft-°F

Thermal Expansion

6.5 µm/m-K

Other Material Properties


0.5 g/cm3 31 lb/ft3

Dielectric Strength (Breakdown Potential)

0.5 kV/mm 0.020 V/mil

Limiting Oxygen Index (LOI)

24 %

Common Calculations

Stiffness to Weight: Axial

18 points

Strength to Weight: Axial

47 points

Strength to Weight: Bending

86 points

Thermal Diffusivity

0.17 mm2/s

Thermal Shock Resistance

58 points

Followup Questions

Further Reading

Wood Handbook: Wood as an Engineering Material, Forest Products Laboratory, USDA Forest Service, 1999

CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015