Understanding Wood Checking
As a homeowner with a log home, you may have noticed small cracks or splits appear in your logs over time. These unsightly blemishes are known as checks in the wood industry. However, it’s important to understand that checking is a natural occurrence in all wood, and it’s not necessarily a sign of structural damage or decay. In fact, checking usually happens early on in a log’s life and is integral to how the wood grows and adapts to its environment.The Nature of Cracks and Splits in Log Homes
While checking or cracks in a log home may not pose a structural threat, they can be aesthetically unappealing. Checks can range from small, shallow cracks to larger, deeper splits that penetrate the log’s center. In severe cases, checks can lead to water penetration, which can cause rot and decay.Causes of Wood Checking
Several factors can contribute to wood checking, including humidity, temperature changes, and improper seasoning. The most common cause of checking is uneven drying. When a log dries, the moisture content within the wood releases. However, as the wood dries and the moisture content decreases, it shrinks, leading to wood checking and splitting. In addition to drying, other factors that can cause checking include:- Exposure to direct sunlight and high temperatures
- Exposure to water and moisture
- Improper storage and handling
The Role of Shrinkage in Log Home Cracking
As previously mentioned, checking occurs when the wood dries and loses moisture content, causing it to shrink. However, not all shrinkage is equal. The wood shrinks twice as much radially (in the direction of the growth rings) than it does tangentially (perpendicular to the growth rings), which contributes to the formation of cracks and splits in logs.Radial Vs. Tangential Shrinkage in Wood
Radial shrinkage occurs when the wood loses moisture from the center of the log towards the bark. This type of shrinkage results in logs that are shorter and wider than before. Tangential shrinkage, on the other hand, occurs when moisture evaporates from the sides of the log perpendicular to the growth rings. This makes the log thinner and narrower. How these two types of shrinkage relate to log checking: Radial shrinkage causes the wood to pull apart from the center of the log, creating radial checks. These checks generally run straight along the length of the log. Tangential shrinkage, on the other hand, causes checks to form perpendicular to the growth rings on the exterior surface of the log.Preventing and Treating Log Home Cracks
While checking is a natural occurrence in all wood, there are several steps you can take to prevent or minimize checking in your log home. One crucial step is proper drying and seasoning of the logs before construction begins. This process allows the wood to stabilize and dry slowly, which can reduce the likelihood of checking. Other preventative measures include:- Applying a clear wood sealer or stain to exterior logs to protect them from moisture
- Installing gutters to prevent water from pooling around the base of the home
- Avoiding overexposure to direct sunlight and heat sources
- Filling the checks with epoxy or a wood filler to prevent water penetration
- Replacing severely damaged logs
- Sanding or Planing the surface of the logs to reduce the appearance of checks