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
0.38
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
Density
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