Log homes have some characteristics that are very different from conventional homes, and it’s crucial for home inspectors to understand them.
Settling is the loss of wall height over time. It’s one of the major concerns for a log home. Let’s look at some of the causes and consequences of settling.
Allowances must be made during construction of log homes to accommodate the inevitable process of settling because a variety of components can be affected.
If the home has a gable roof, and the gables are built using green logs, the gable wall will settle as the logs dry. Typically, in framing a gable roof, the ends of the ridge are supported by the gabled wall at each end of the roof. If that wall is losing height because the logs are settling, what’s happening to each end of the ridge? If the ridge is securely fastened to the logs, roof connections are going to be stressed until some roof or wall framing component breaks or becomes disconnected. These are both bad events. Which component breaks or where the disconnection happens will vary depending on how the home is built.
Doors and Windows
If the contractor understands log homes, the doors and windows will have a settling space above them so that the weight of the wall will not bear on the doors or windows. The settling space is typically covered with trim which is installed in such a way that it can slide as settling takes place.
As walls lose height, anything connected to them also loses height. If a staircase rests on a floor at the bottom and, at the same time, is attached to a landing or to floor joists that are losing height as the walls settle, after a while, the treads will no longer be level. There are a number of ways to correct this, but you have to know enough to look for it.
Partition walls in log homes are typically framed conventionally. This means that although the log walls will settle, the partition walls will not. If the partition walls are framed from floor to ceiling, as they would be in a conventional home, something bad will happen as the settling log walls transfer weight to the partition walls that were not designed to bear weight. The stress will build until the weakest component fails.
Plumbing Pipes and Rigid Conduit
In homes of two stories and more, plumbing pipes and rigid conduit that are installed vertically will accumulate stress as log walls settle. There are ways to accommodate settling. Using slip joints and coils are two methods for overcoming this problem. Flexible copper tubing is sometimes used instead of rigid copper pipe. It’s also possible to see the methods and materials used, but sometimes you have to make an educated guess. Remember to disclaim anything you can’t see.
In order to accommodate settling, log homes sometimes use screw jacks, which must be adjusted occasionally. Screw jacks are often hidden behind trim, so you have to know where to look for them. Posts that support porch roofs and lofts are common places to find screw jacks. They may be installed at the top or bottom of a post.
Most home inspectors are familiar with wood decay. Design features that direct runoff onto log walls, especially log extensions at outside corners, will encourage the development of decay. This is decay you can see because it usually appears as dark discoloration. It happens first at log extensions because the exposed end-grain absorbs moisture faster than the rest of the log's surface.
Logs become deteriorated by weather. Finish coatings are designed to protect log surfaces from UV damage and excessive checking caused by log drying. Some coatings also prevent attack by some wood-destroying insects.
Wood-destroying insects usually leave some clue as to their presence. The size, shape and condition of entry and exit holes can indicate what species of insects are likely to be living in the logs. Both termites and carpenter ants grow wings and swarm to new locations every so often. When they arrive at their destination, they shed their wings and burrow into the wood. Wing piles are a sign that you shouldn’t miss. You may also see dead insects on window sills inside the home if the swarm originates inside the home.