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Log Cabins - A little background
Types of Log Cabin
There are two kinds of log cabins: "handcrafted" and "milled" (also called "machine-profiled"), made with a log house moulder. A handcrafted log cabin is typically made of logs that have been peeled but are otherwise essentially unchanged from their original natural appearance when they were trees. A milled or machine-profiled log cabin is one constructed of logs that have run through a manufacturing process to remove natural features and imperfections of the log and convert them into timbers that are consistent in size and appearance.
Handcrafted log cabins have been built for centuries in Scandinavia, Russia and Eastern Europe. The Scandinavian settlers of New Sweden brought the craft to North America in the early 1700s, where it was quickly adopted by other colonists and Native Americans. In the 1920s, the first milled log cabins appeared on the market, using logs that were precut and shaped, rather than hand-hewn. Most log cabins today are of milled variety mostly because they require less labor intensive field work and there are many more options available than with handcrafted alone.
Any timber from large to small will have moisture in it when it is fresh cut. Log cabins of all types experience varying degrees of moisture content. In the case of "handcrafted" logs this moisture will naturally leave the timber, drying it out until it stabilizes with the climate it is in. This drying out causes movement and adjustment in the timber. As the wood dries the individual cells on the exterior of the crafted log will seal up. The remaining moisture in the center of the timber keeps trying to escape and will eventually open a crack in the crafted log. This crack, also known as a "check," can continue to the heart of the timber, sometimes leaving a large crack on the side of a cabin. This occurs in all "handcrafted" log homes, regardless of construction method or how the timbers are allowed to dry.
Milled logs are processed in a different manner than hand crafted logs. Logs destined to become Milled logs can become one of several types depending on the desired quality and end result.
Kiln Dried Timber
Mills have the option of artificially accelerating the drying process. Green timber (i.e. timber with a moisture content of 25% or sometimes higher) is placed inside a large oven where heat removes moisture from the logs. Kiln Drying can cut down the dry time required by the manufacturer in order for production, from many months to a number of weeks, and usually results in an average moisture content of 18-20%, average being the mean moisture content of the outside of the log and the center of the log.
Glue Laminated Timber
Full trees are brought to a mill equipped with a dry kiln, the bark is removed and the trees are sawn into boards usually no thicker than two inches thick. These boards are then taken to the dry kiln where because of their size they can be dried without causing severe damage to the wood. Timber destined for glue lamination must be brought down below 15% moisture before the lamination process will even work so typically these timbers are dried to around 8-10% moisture. The drying process varies on the species of lumber but can be done in as little as a week. Once the drying process is complete the planks are sent through a surfacer or planer which makes the face of the lumber perfectly smooth. These planks travel to a machine which then spreads a special glue on the interior boards. A high pressure clamp holds the newly reassembled timbers under pressure for 24 hours allowing the glue to dry. Once the glue has dried the end result is what is called a "log cant" that is slightly larger than the buyers desired profile. These log cants are run through a profiler and the end result is a log that is perfectly straight and uniform "Laminated" or "Engineered" log.
Methods of log cabin construction
The load forces of the building are transmitted to the foundation through the wooden logs. Milled logs cabins are "Chinkless" cabins, the logs are milled to fit closely enough together so as to remove any need of chinking. Since the logs bear the weight of the building, any shrinkage of the logs is cumulative and the shrinkage results in the settling of the building, that is, the vertical dimensions of the building shrink as the logs shrink. Our Milled log cabins are constructed with a Tongue and Groove system that helps to align one log to another as well as create a system for sealing out the elements, the logs and notched where they overlap at the corners.
Interlocking Notch - a notch is cut into the top of one log and bottom of another, these two logs then interlock creating a tightly sealed corner.
Typical profile of our milled logs
Milled log homes have an assortment of profiles that are usually picked by the end customer. Just about every profiled log on the market today features an integral tongue and groove milled into the top and bottom of the log that aids in stacking as well as eliminates the need for chinking.