Q.When you go to a timber mart to collect timber for the construction of a new house, how will you select good quality timber?

Good timber is chosen for being mature heartwood rather than sapwood — straight-grained, dense, defect-free, properly seasoned, and naturally resistant to decay and insect attack.

When selecting good quality timber for construction, the following features should be checked:

1. Heartwood over sapwood — the central, older part of a tree trunk (heartwood) is dead, hardened, and often impregnated with resins/tannins that make it dark-coloured, dense, and resistant to decay and insect attack, unlike the outer, lighter-coloured, living sapwood, which is softer and much more prone to fungal decay and termite damage. Good timber should be predominantly heartwood.
2. Growth ring pattern — timber with closely and evenly spaced growth rings generally indicates slow, dense growth and greater mechanical strength; very widely spaced rings often indicate weaker, fast-grown wood.
3. Grain and texture — straight-grained wood with a uniform, fine texture is stronger and easier to work with than wood with twisted or irregular grain.
4. Freedom from defects — the timber should be free from knots, cracks, splits, insect holes, and fungal/decay stains, all of which weaken the wood and make it unsuitable for load-bearing use. …