Clearing the Air About Kiln-Drying!

"Kiln-dried logs make better log homes!" That is a great sales pitch. But do the facts actually support the claim? Here are a few questions you need to ask:

Are heavy timbers the same as 2x4 wall studs?

Hardly. It is realistically impossible to take a log cut green in the forest, place it in a lumber kiln and dry it to the level of moisture found in dimensional lumber sold at building supply stores. The timbers would have to stay in the kiln for so long that the cost to the log home company would be prohibitive.

Can you read a kiln schedule?

If the answer to that question is no, then how do you verify that the "kiln-dried logs" some salesman wants to sell you weren't popped into the kiln for a few hours and then hauled out with most of the moisture still trapped in the wood cells?

Is kiln-drying an excuse for poor building practices?

It is a fact of life that log walls settle. In other words, the overall height of the wall decreases as a result of log shrinkage (moisture escapes and wood cells contract) and compaction (the weight of the logs and roof crush wood fibers). All too often kiln-drying is touted by salesmen as a cure-all for settling. This is simply not true! If a log wall system used by a given company isn't fully adjusted for wall settling, the homeowner is very likely to regret that fact later.

Are kiln-dried logs really lighter?

Lighter than green logs sure, but this is not necessarily true in regards to air dried logs. If you were to take two otherwise equal logs, air dry one and kiln-dry the other to equal moisture content they would weigh the same. Again the catch is that kiln-drying a log of any substantial diameter to its core is going to be cost prohibitive because of the thermal mass of the log.

No matter what moisture content you kiln-dry a log to, as soon as you remove the log from the kiln it will begin to adjust its moisture content to match the ambient humidity of the air around it. If the air is more humid, the log will draw in moisture. If the air is drier, the log will release moisture (just as if you put a wet sponge on top of a dry sponge). It won't happen overnight, but it does happen and there is nothing that can be done to stop it. The laws of nature dictate that logs reach equilibrium with the atmosphere around them.

Is there any advantage to kiln drying logs?

Of course. International trade laws require that American companies kiln-dry lumber before it is exported to Europe (and visa versa). This "sanitizes" the wood, killing any fungi or biological pests native to North America that might infest their forests. So if you intend to buy a log home package from an American company and then build it in Europe, you are required to use kiln-dried logs.

So what is the difference between air-drying and kiln-drying?

The real purpose of kiln-drying is not to make lumber drier than or lighter than air dried lumber. The purpose is to reduce the time it takes between when a green tree is cut down and the finished product can be sold at market. In addition in the case of dimensional lumber it is also used to help reduce warping (since Heritage air dries their logs before sending them through their mill, this is not an issue).

In the end, air-drying logs for an extended period of time is just as effective at reducing the moisture content and weight of logs as is kiln drying. The difference is that as a consumer how do you know that the kiln dried log was actually in the kiln long enough to dry the log to the core. Can you read a kiln schedule or do you have to take the sales person word for it? For the manufacturer the difference between these two drying methods is whether they want to keep a large back lot of logs that are drying or do they want to keep those inventories down by popping green logs into the kiln.

Before the 1930s, not a single log home built in the world employed kiln-dried logs; and there are log structures in Europe that have been standing for 300 years. Don't fall prey to marketing promises that offer "quick-fix" solutions rather than sound construction practices.

Heritage Log Homes has been in business since 1974.

Since that time, Heritage Log Homes has never used kiln-dried timbers (unless exporting to Europe as mentioned above) because they know from experience that this practice makes a better sales pitch but not a better log home. In the end, they recognize that all logs are "air-dried," even the kiln-dried ones. In other words, all logs must stand in service for some time period before the moisture content inside the wood reaches equilibrium with the moisture content of the air around it. During that time, the walls will settle!

Heritage's Self-Tightening Thru-Bolt with compression springs give homeowners the assurance that they have the best-engineered log homes available. Their total log wall settling system and proven sealant package means tight joints and minimal concerns for buyers. Furthermore, Heritage provides the highest grade of timbers of any log home manufacturer.

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• Frank Masie & Laura Merkin
• John & Coleen Ruggieri
• Kent & Sonja Hardwick and Marge & Don Seward