LOG HOME and LOG CABIN EDUCATION INFORMATION
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LOG HOME and LOG CABIN EDUCATION INFORMATION
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Moisture Content Bound cell water in the fiber of a tree is your worst enemy. Logs will only shrink in diameter not in length. This is due to fibers that run the length (longitudinal) in a tree. These fibers are like straws the pull nutrients up from the base to feed the tree and hold moisture during the life of the tree. The key to a log home is to minimize movement and movement is caused by an excessive amount of bound cell water at the core of a log. You will hear different stories from one manufacturer to another, which will become very confusing. Here we will explain and expose the truth about what manufactures tell you and how they should be educating you to make the right choice in selecting your log home manufacturer. Today there are several log home manufacturers’ telling you that they are kiln dried, air-dried or a combination of both. Well as we grew up we were told that when you go down to the lumber store, buy kiln dried because it is the best. You run down to the lumber store to pick up (12) 2” x 6” kiln dried boards and are there for an hour looking down the length of the board for straight ones because they are bowed, warped and twisted. The lumber was wet and the deeper you went into the bunk of lumber it was even wetter *note see section on kiln dried vs. kiln dried core * The lumber is wet due to an excessive amount of moisture left from kiln drying. Now the next bunk over known as kiln dried core (KDC) is dryer and you can pick out your 12 boards in 12 minutes and be gone. Kiln dried means surface dried. In the lumber industry the surface is dried at 18% moisture as it goes down the conveyer belt, stacked in a bunk and banded. In the log home industry it is much the same. Kiln dried means 19% or less at only one inch in to the log. The Timber Products Inspection Agency (TPI), the agency that regulates the Log Home Industry only requires moisture to be regulated to one inch due to limitations of the moisture pins that penetrate into the logs only 1 inch in. See example photos below.
Air dried logs are on the same principle. The logs can only air dry down to the relative humidity where they are standing in the forest or where they are stored at the manufacturers mill. If the location of a manufacturers mill is where the relative humidity during the summer or winter months is 80%, I have concerns on how they can say that they air dry or kiln dry any wood down to or below 19% moisture content. If they dry at a very high temperature in a short period of time the log will implode rapidly causing the fibers to separate and you will have more checking (cracking) in the logs. When the logs are taken out of the kilns there will be humidity saturation balance where the logs balance to the relative humidity where they are stored. Manufacturers that use green trees will see much less humidity saturation balance compared to manufacturers using dry dead standing trees. When a tree is alive in the forest it has gates that open in the morning to bring in moisture and when it warms up these gates close to keep in moisture. When a tree dies in the forest, these gates remain open allowing for a higher percent of moisture to reenter during the humidity saturation balance period of time. When green trees are harvested these gates are closed and when kiln dried locks these gates allowing for a very small amount of moisture to re-enter during the humidity saturation balance period of time. When you ask a manufacturer what their moisture content is you will hear one key word that should alarm you and that is when they tell you “our AVERAGE moisture content is” 19% or less. You do not want an average moisture content you need a company that will give you a “CONSTANT” moisture content under 19% from one end of the log to the other and all the way through. Here is how they arrive at an “average” moisture. Log home manufacturers that only kiln dry and air dry take a log, weigh it then place in their kiln or set out to air dry. After a couple of days in a kiln they pull the log out and weigh it again, use a mathematical formula to arrive at an average moisture content. Most log home manufacturers today are using a product known as “ Dry Dead Standing” *note see section on Kinds of Logs*. What they do not tell you is that when a tree dies in the forest gravity pulls moisture down towards the base. When you cut that tree and lay it down, the end that was on the stump will have a higher moisture content than the other end that was at the top. Say one end is 35% moisture and the other end that was on top is 20% and they dry the log down to 19% at only 1 inch down in. Can they tell you what the moisture is 2 inches in to the log. All they can do is give you an average by weight and species. You will have a variation of moisture content from one end of the log to the other end and one end will shrink more excessively than the other with this variance in moisture. Manufacturers that make bold statement like “we produce over 300 homes a year” should be looked at more closely under a microscope. For example: I heard a customer talking to one major manufacturer at a show last year and the sales person representing the manufacturer was boasting that their company sold over 800 homes the previous year. The customer asked the representative how many kilns they have at the manufacturing facility and he replied quietly and I did not hear. The customer went on to say that if you do over 800 homes a year and with x number of kilns then your logs stay in the kilns an average 3-4 days, right. The representatives jaw dropped for a moment and when he regained some composure told the customer that maybe he didn’t want to do business with his company and walked away from the customer. The sad thing is that this customer was right. To kiln dry logs at 19% moisture to 1 inch into the log would only take a couple of days. Again this is why you should never settle for an average moisture content. These logs will have an excessive amount of bound cell water at the core and will continue to shrink as the bound cell water evaporates over several years. These logs will shrink and gaps will appear between each log and you will have to chink your home *Note see section on chinking* every 5-6 years at a cost of $6,000 per 1,000 square foot of home. A 2,000 square foot home will cost between $12,000 and $14,000 every 5- 6 years. You lose appreciation of your home while a contractor comes in and chisels out the old and reapplies chinking inside and outside on your home. Think of the time you lose, the mess it creates and the amount of money it costs. Is it really worth saving a couple of thousand dollars on your log package at first. This is an industry where you will most defiantly get what you pay for. S do not go into purchasing a log home with a cheap frame of mind because it will cost you more in years to come. If settling of your log home walls is an issue and it should be, here is the golden question for any log home manufacturer to tell if they are being up front an honest about how much their logs will shrink. Ask if they use a settling jack or screw jack on their vertical poles *note see section on Settling Jacks*. If they say yes to using settling jacks or screw jacks on the vertical poles you now know that their log walls will be shrinking excessively and you should be aware. Settling jacks and screw jacks are designed to allow the homeowner to lower the roof as the log walls shrink. If you do not lower the roof as the walls shrink your roof will come off your walls causing structural problems and costing you thousands of dollars.
Consulting firms that help you through the building process are well worth your time and money. Not knowing the in and out's of building a log home or timber frame home can become very frustrating. Custom Woodcraft Builders out of Indianapolis, Indiana serve the Mid-Western States. If anyone has seen it all...it is Custom Woodcraft Builders. Sources of expert timber frame and log home building advice: www.customwoodcraftbuilders.com For log and timber trusses and entryways - please visit timbertrusses.net and timbertruss.net. To learn about building options with authentic reclaimed lumber, beams, logs & timbers for true historical 'green' building, please visit reclaimedwood.biz and reclaimedtimber.org. If you are interested in more information about timbers, timber framing and log and timber frame construction in general, please visit the following sites: Be sure not to miss a wide array of log home and log cabin suppliers, builders and accessories at the Outdoor Sport Lake & Cabin Show in Fort Wayne Indiana March 12-14, 2010. This event is produced by Coliseum Productions Inc.
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