Despite the great structural properties of wooden-frame structures, they also have their limitations.
- Wood is easily flammable.
- Wood is flammable when dry and burns readily, due to the air-filled voids within the wood. Fresher woods tend to burn more easily due to resins and oil, which aid in combustion.
- Impacts the environment.
- The adoption of wood construction over time has contributing to the worldwide problem of deforestation. The effects of deforestation include change in animal habitat, soil erosion, and recovery times due to the slow growth-rate of trees.
- Due to it's origins from nature, there is less uniformity in strength.
- Depending on the type, location and age of the tree used, various factors affect the structural strength.
- type of log cut
- slope of grain
- presence of knots or holes
- moisture content
- Susceptible to moisture.
- Wood shrinks/swells when it loses/gains moisture below its fiber saturation point. This natural behaviour of wood is responsible for some of the problems sometimes encountered when wood dries.
- For example, special cracks called checks can result from stresses induced in a piece of wood that is drying. As the piece dries, it develops a moisture gradient across its section (dry on the outside, wet on the inside). The dry outer shell wants to shrink as it dries below fiber saturation, however, the wetter core constrains the shell. This can cause checks to form on the surface. The shell is now set in its dimension, although the core is still drying and will in turn want to shrink. But the fixed shell constrains the core and checks can thus form in the core.
- Another problem associated with drying is warp. A piece of wood can deviate from its expected shape as it dries due to the fact that wood shrinks different amounts in different directions. It shrinks the most in the direction tangential to the rings, about half as much in the direction perpendicular to the rings, and hardly at all along the length of the tree. Where in the log a piece was cut will be a factor in how it changes shape as it shrinks