Yes, you should worry about these problems; yet, at the same time, you do not have to worry about these problems. Molds, bugs, termites, fungus … all of these issues are problematic in any home, and it doest not if it is a solid brick home or a log home. Nonetheless, because of construction techniques and the mass of wood in a log home, you do need to look more closely at these issues and make some decisions when building a log cabin or home.
Let's start at the beginning, and that is the root of a log cabin or home — the TREE. A tree is a living-breathing thing right up until the moment it is cut down. While still alive, a tree plays host to all sorts of organisms. Bugs eat, sleep and lay their eggs in the bark and wood. Molds and fungus will grow just about any place if there is the right moisture content. If we are going to be able to control these potential enemies, we need to understand how they get there, how they live and what they need to survive. Let's first look at the life cycle of a tree. It starts life as a seed, germinates and grows to a seedling and over years develops into a mature tree. Then along comes a logger and he cuts down our tree, which is destined to become a log home.
As soon as the tree is cut, it begins to decompose. This is normal and all things do this, but we want to stop the decomposition of our wood for this log is destined to be part of our log cabin or house. But Mother Nature does not know what we plan to do; and molds and fungus do their part and continue the decomposition of the tree with the intent of turning our log back into dust. The insects also continue to do their part as they continue to eat their way through our log. This is all part of nature's process of decomposition but we want to stop that process and preserve the tree for hundreds of years.
As we said, molds and fungus begin turning our log into dust immediately. What molds and fungus need to survive and prosper is a warm, moist environment with a food source. By weight, a tree trunk is over 40% water. As long as there is moisture in the log, this will be a viable environment for our molds and fungus and they will continue to consume the tree trunk. Insects likewise do their part. As the tree rots, the wood becomes softer and more and more insects fine it a nice place to eat, live and raise a family. If left unchecked, the process continues until nature has totally decomposed the tree. If we left this tree lying on the forest floor, in no time at all, this tree would become a rotten skeleton of what was once a once mighty tree.
In our case, we want to break this natural cycle and preserve this tree trunk using it to build a log cabin or a log home. What we have to do is break the life cycle of the molds, fungus and insects. How a log home manufacture breaks this cycle is dependent on the company, but they all must break the cycle. Let's look at what the fungus and mold needs. Their needs are pretty simple. They need a moist environment and, for optimum growth, it should be both moist and warm. So all we need to do to stop them is dry the wood out and then keep the wood from getting wet. As for the insects, they are a bit more complicated as some insects will love dry wood as well as moist wood. Further, when the tree was cut down, there were large numbers of insects already living in the wood and they have laid thousands of eggs just waiting to hatch and eat away at your log home. Somehow we have to break their life cycle, and then we have to protect the wood from additional intrusion by bugs. Let's now look at what different log home manufacturers do to break the life cycles of molds, fungus and the wood-destroying insects.
All log manufacturers first remove the bark. This is important as the bark used to protect the inter parts of the tree like skin protects our bodies. The inner part of the bark is called the cambium layer, and it is where the tree's sap rose and fell moving nutrients and water between the roots and the leaves or needles of the tree. Bugs, mold and fungus love this region of the tree. All log home manufacturers remove the bark to destroy this important habitat for the bugs, molds and fungus. After the bark is removed we next have to remove the moisture and kill off the insects and bugs. Manufacturers vary as to how they handle these problems. There are two camps of thought. On one extreme you have the log home manufacturers that build with green or wet logs and on the other extreme you have the log home manufactures that build with fully kiln-dried logs. Between these two extremes are all the manufacturers that do air drying, and partially kiln dry their logs.
Let's first look at those that build with green or wet logs. The logs will be stripped of their bark and stacked for a while awaiting the next order for a log home. As soon as the log is cut, it begins losing moisture so this will allow some of the moisture to escape and will start the drying process. If the manufacturer protects the logs under a shed, it will keep the rain off and speed up the drying process, but the amount of water in a home build of green logs can be huge. A typical log home will need to lose up to 5 tons of water before it becomes fully dry. When an order comes in, the logs are sent to the construction site and the log home or cabin is built. Green logs are very heavy. An eight-foot log that is about 12 inches in diameter will weigh over 200 pounds but over time, the log will lose this water. One thing that happens, as it dries, is the logs shrink and the whole wall will settle. When you are looking for log home manufacturer, you can always tell which log home builders construct with green or wet logs because they must have some method of handling shrinkage and settling. Some of them are not straightforward when you ask these questions because they know that building with green logs can lead to potential problems and increased maintenance over time so question whomever you are thinking of building with. Ask them if they "do anything to compensate for settling or shrinkage." If they tell you everyone does, they are wrong. No matter, if they leave gaps above the windows and doors to allow for the log wall to shrink and settle or have slots where they nail doors and windows to a log walls, their logs are green enough to demand some sort of mechanical solution to compensate for the shrinkage. There is another hint. If the builder talks about through bolts that need to be tightened or they talk about self-tightening springs, they are building with wood that is green or wet enough that it will shrink or settle.
This is the same process used by the pioneers and some of those cabins have lasted hundreds of years, but they do require additional maintenance, especially in the first few years. While drying your logs this way will work given time, these log home manufacturers need to address the bug, mold and fungus issues immediately and so these manufacturers will typically put some poison on the logs or will dip them in a tank of poison. Modern man has developed a wide range of pesticides, insecticides, fungicides and herbicides. There is a poison for just about anything you may want to kill. This can be sprayed on the logs but more commonly the manufacturers that use these poisons will dip their logs into the solution. The poison soaks into the wood and kills the bugs, the fungus or the molds. The poison has residual properties and can continue to kill molds, fungus and bugs for a long time to come. This is good and bad. Remember that this same poison that is killing the insects, molds and fungus, is being released into your home day after day, year after year. If your log home manufacturer uses this method of control pest control, do your homework. Find out what type of poison and what concentrations they are using. Do your research and find out if the poison could have any harmful side affects for adults, children or pets or people with allergies.
Some log home manufacturers build with huge logs and kiln drying is not feasible. Some of them will stack these huge logs for a log time in a controlled environment and will dry their logs this way. This is an extremely expensive process and is normally only used on high end, one-of-a-kind houses. Most log home manufacturers that do not build with green wood kiln dry the logs. Let's see how this is used to kill off the bugs, mold, and fungus and get rid of the water. These log home manufacturers place the whole log into a large kiln. Some are the size of a warehouse. If they leave it in the kiln for a few days, they are not truly trying the log. It can take three or four days to dry out just a piece of lumber much less a log. The log home manufactures that bring the internal water content down to 13% – 16% will leave them in a kiln for up to 30 days and will slowly move the temperature up to as high as 180 degrees. The benefits of kiln drying are that it dries the log and means you do not have to compensate for shrinkage and settling. It also allows them to control the checking on logs and any logs that warp or check too much can be discarded before they are placed into your home. Being dried in a kiln also kills off all of the insects and destroys their eggs and larvae breaking their life cycle. This means that these manufactures do not need to put poison on the logs you are using for your house. There are other benefits to be gained from using kiln-dried logs. One of them is that you can put a stain and sealant on your logs immediately. With a log home that builds with green lumber, you have to allow the moisture to escape from the log and so you need to wait a while before putting on an exterior or interior finish. Kiln drying also has the benefit of crystallizing the sap in the tree sap. Homes built with green wood can ooze sticky sap for years to come. The last benefit to kiln drying is something I touched on earlier and that is quality control. When you look at a log, there is no way of guessing how it is going to dry. It can twist, warp and split badly. You can see this easily if you ever go into a lumberyard. Have you ever noticed that out of a pile of boards there will always be a few that do some wild warping? They can twist and bend as much as a foot over a ten-foot length. When logs are fully kiln-dried, if you find any of these rogue logs, they can be discarded. If you build with green wood, you will never know this until it is a part of your home. Checking is another big issue with logs. All logs will check and this can not be stopped, but, by kiln drying, you can discard logs that check too badly or you can turn them in such a manner that bad checks no not collect rain water and lead to trouble spots on the outside of your log home.
In conclusion, you do need to be concerned about mold, fungus and insects with a log home. Modern man has developed ways to solve these problems. Some methods include air-drying the logs, using poisons to kill off the insects, molds and fungus, and kiln drying to kill pests and their eggs. Armed with this information you should be better able to make informed decisions when talking to log home manufacturers and dealers.