Spruce

1.5-2 usd/kg
Circularity potential
Very high
Strength
Medium
Production energy
Ultra low
Stiffness
Medium
Embodied CO2
Ultra low
Density
Ultra low

Spruce is a light coloured softwood, with little contrast between heartwood and sapwood. Unlike pine, it has almost no odour and the wood has a uniform, relatively knot-free appearance. It is used in light construction work, engineered wood (glulam and plywood), wood fibre products and pulp (paper making). General purpose timber is relatively inexpensive.

Spruce is prized for its superior acoustic properties. It has uniform properties and shrinks little after seasoning. These qualities are utilised in quarter-sawn soundboards for musical instruments, such as violin, cello and piano. The highest quality musical instruments are produced from spruce that has been specifically selected before felling and air dried for a decade or more. These are some of the most expensive timbers available.


Sustainability concerns
Non-renewable ingredients
Raw material generates polluting by-products
Low circularity potential
Potentially toxic in use


Glued laminated timber (glulam, also sometimes GLT) is a structural lumber produced from wood cut into uniform strips (lamella), finger jointed to make long lengths, and bonded together with high strength adhesive, which is typically melamine (MF). The thickness of the lamella is usually 45 mm. For curved or arched beams, the layers may be from 6 to 45 mm, depending on the requirements. And glulam is available in a range of dimensions, from 80 to 1,280 mm high, 80 to 280 wide, and over 40 m long.

It is used in home construction, multi-story buildings, agricultural and industrial facilities, recreation and sports centres. It is suitable for the roof structure as a visible component (all knots are sound knots and knotholes are patched), main beams with large spans, columns and floor structures. The bending strength of depends on the tensile strength of the layers (lamellae) and finger joints between the assembled lengths. Spruce is the most commonly used timber, but pine, Douglas fir and larch are also popular – all types of timber may be used.

In additional to straight beams with a constant cross section, it is possible to make tapered beams, curved beam and pre-cambered parallel beams, double tapered or pinched cambered beams, fish beams, trussed girders and free forms (curved profiles). The same as solid wood, it machines well and can be pre-cut to profiles before arriving on-site, such as to marry with rafter and purlin profiles, or for joints (rafter notch, stepped, tenon, dovetail, log house).


Design properties
Cost usd/kg
1.5-2
Embodied energy MJ/kg
8-11
Carbon footprint kgCO2e/kg
0.6-0.9
Density kg/m3
340-480
Tensile modulus GPa
7-14.5
Tensile strength MPa
16.5-26
Modulus of rupture MPa
28.61–62.62
Compressive strength MPa
20-32
Hardness Mohs
1
Janka hardness kN
2.3-3.1
Thermal conductivity W/mK
0.13
Temperature min-max °C
-40 to 150
Thermal
insulator
Electrical
insulator