Wood can shrink and expand as the wood’s moisture content changes in the daily and seasonal relative humidity of the atmosphere. A lumber yard is supposed to dry out lumber before it is shipped to reduce issues with using it for construction. Even if it is dried properly, other factors can affect the moisture content of wood. These factors need to be taken into account when constructing a home.
Lumber can change dramatically in size as it gives up moisture. A piece of wood doesn’t shrink the same amount along all of its dimensions, though. The greatest amount of shrinkage always occurs across the face of the grain. Since wood is hygroscopic, it changes dimension based on the amount of moisture it contains.
Planning for Shrinkage
When building a home, this shrinkage of lumber from the lumber yard needs to be kept in mind. This means you need to plan. To minimize cracks in drywall and ceramic tile, squeaks in staircases and flooring and spaces between countertops and backsplashes, allow the house to dry as long as possible before applying finishing treatments. Another way to avoid shrinkage issues is to use different materials in problem areas: engineered wood, floor trusses and metal floor joists.
There are other ways you can minimize, mask and otherwise manage wood movement. It requires attention to detail during design, installation and finishing. Elements should be detailed so they are not affected by changes in cross-sectional dimensions. Connections need to be given particular care. If detailed appropriately, you can minimize additional restraint that should prevent timber from moving as it shrinks.
Timber from a lumber yard can shrink different amounts depending on the wood. It is important to keep in mind the amount of moisture any piece of lumber might contain, how much it might shrink and in what directions it will shrink. This change in dimensions can have a dramatic effect on a home. Attention to detail can minimize the damage.