Wood is a complicated material to work with. However, the mechanical properties of structurally graded timber are somewhat predictable if the service environment and the loading conditions are known. Although codified procedures and formulae for design both benefit from these known characteristic properties, a novice designer could face several problems when designing joints and connections if due consideration is not given
to the following possibilities: splitting of timber, stresses induced due to changes in moisture content in service, elevated temperature, corrosion of connectors due to chemical interaction with the wood, decay of timber due to moisture build up around inadequately detailed joints.
To help prevent timber splitting, designers of joints and connections need to consider the mutual orientation of the fastener, the load and the grain direction.
Thermal expansion and temperature changes can change the strength and stiffness of timber.
Moisture content and drying out can affect the strength and the stiffness of timber and can cause significant changes to its dimensions.
Timber is susceptible to decay when exposed to higher levels of temperature, humidity and oxygen.