Wood

Wood (red oak) strength, stiffness, density and thermal properties, with their source.

A bracket in Wood, natural grain finish.

Mechanical
Yield strength	not given (tensile used)
Ultimate tensile strength	modulus of rupture99MPa1
Compressive strength	46.6MPa1
Flexural strength	modulus of rupture99MPa1
Elongation at break	not sourced
Young's modulus (stiffness)	bending MOE12.5GPa1
Density	681–702kg/m³2
Strength to weight	143kN·m/kg
Stiffness to weight	18.1MN·m/kg
Poisson's ratio	mu_LR0.351
Shear modulus	4.63GPa
Bulk modulus	13.9GPa
Speed of sound	4,252m/s

Stiffness against densityHigher and further left: stiffer for its weight

Strength against densityHigher and further left: stronger for its weight

Thermal
Thermal conductivity	across grain0.18W/m·K3
Thermal expansion	parallel to grain3.1–4.5µm/m·K3
100 mm part over a 50 °C swing	19µm growth
Specific heat	solid wood1,700J/kg·K3
Heats up and cools (diffusivity)	0.153mm²/s
Thermal shock resistance	244W/m

Thermal conductivity against densityHigher and further left: spreads more heat for its weight

Thermal expansion against thermal conductivityLower and further right: warps less when heated

Sources3 documents: USDA Forest Products Laboratory

Values for: Natural. Northern red oak (Quercus rubra), clear straight-grained specimens at 12% MC, parallel to grain unless stated; USDA FPL Wood Handbook FPL-GTR-282 (2021) Ch. 4 and Ch. 5

1
Wood Handbook (FPL-GTR-282), Chapter 5: Mechanical Properties of WoodUSDA Forest Products LaboratoryUltimate tensile strength: modulus of rupture (no direct tensile value)Compressive strength: compression parallel to grain (maximum crushing strength), 12% MCFlexural strength: modulus of rupture (static bending), 12% MCYoung's modulus (stiffness): bending MOE, parallel to grainPoisson's ratio: mu_LR (red oak group, ~12% MC)
2
Technical Note 218: Weights of Various Woods Grown in the United States (1953)USDA Forest Products LaboratoryDensity: average weight of clear wood at 8% and 15% moisture content
3
Wood Handbook (FPL-GTR-282), Chapter 4: Moisture Relations and Physical Properties of WoodUSDA Forest Products LaboratoryThermal conductivity: across grain, 12% MC (Table 4-7, approximate)Thermal expansion: parallel to grain, ovendry wood, range across speciesSpecific heat: solid wood (all species), 12% MC, 27 C

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Thermal properties of Wood

Thermal conductivity of Wood

Wood has a thermal conductivity of 0.18 W/m·K (0.104 BTU/hr·ft·°F). Basis: across grain, 12% MC (Table 4-7, approximate). Source: USDA Forest Products Laboratory, Wood Handbook (FPL-GTR-282), Chapter 4: Moisture Relations and Physical Properties of Wood.

Specific heat of Wood

The specific heat capacity of Wood is 1,700 J/kg·K (0.406 BTU/lb·°F). Basis: solid wood (all species), 12% MC, 27 C. Source: USDA Forest Products Laboratory, Wood Handbook (FPL-GTR-282), Chapter 4: Moisture Relations and Physical Properties of Wood.

Coefficient of thermal expansion of Wood

Wood expands 3.1–4.5 µm/m·K (1.72–2.5 µin/in·°F): a 100 mm part grows 19 µm over a 50 °C rise. Basis: parallel to grain, ovendry wood, range across species. Source: USDA Forest Products Laboratory, Wood Handbook (FPL-GTR-282), Chapter 4: Moisture Relations and Physical Properties of Wood.

Thermal diffusivity of Wood

Computed from the conductivity, density and specific heat (k / ρc): 0.153 mm²/s, how fast a temperature change spreads through it.