preservative treatment for log homes

[gte447f]

I'm seeking some guidance on the requirements for preservative treatment of logs used in the construction of log homes. I have a situation where a builder wants to use (actually has already constructed) some southern pine logs as posts to support porch roofs and exterior decks. He got the logs from a local mill and says he has treated them with "bug juice", whatever that is. The building inspector is saying the posts have to be pressure treated so he wants the builder to replace the log posts with pressure treated 6x6's. I am interested in available options for logs used as structural framing members exposed to the elements.

ICC-400 (Standard for the Design and Construction of Log Structures) says that "logs required by the applicable code to be preservative treated shall be treated using processes and preservatives in accordance with AWPA Standards". IRC requires pressure treatment per AWPA U1 for wood structural members supporting moisture permeable floors or roofs exposed to the weather. This would seem to apply to deck posts but not porch posts. The IBC has an additional requirement for wood members that form the structural supports of buildings, balconies, porches, or similar permanent building appurtenances where such members are exposed to weather without adequate protection from a roof, eave, overhang or other covering to prevent moisture accumulation on the surface. Adequate protection could be debateable for a porch post. It seems to me that the logs for the deck posts should definitely be AWPA treated and the logs for the porch posts should probably be AWPA treated for good practice. However, it is my understanding that AWPA does not apply to unsawn logs. I believe it says posts (<16 feet long) and poles (>16 feet long) have to be machine peeled.

Curiously, the building inspector has no problem with the typical wall logs that make up the exterior walls of the house even though they are exposed to the same elements as these posts in question. When I raised that point, he said he was satisfied because the builder bought the wall logs from a log home supplier, even though he has no information or certification regarding how or if the wall logs have been preservative treated.

So, am I interpreting the requirements for AWPA preservative treatment correctly? If so, does the log home industry typically use AWPA preservative treatments for their logs? If not, how do they satisfy the building codes? Maybe because they consider everything adequately protected by roof eaves and overhangs? Looking forward to the forum's feedback. Thanks.

 

[SlideRuleEra]

...does the log home industry typically use AWPA preservative treatments for their logs?

Yes.

Since CCA preservation was greatly restricted several years ago wood preservation choices are more of a compromise than previously.

Borates are widely used for log homes. They are the least toxic of available preservatives, but have limitations when exposed to soil or weather.

See this article for a summary of options. Link

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[oldestguy]

I lived in a log home for some 20 years in Wisconsin. Nothing special was done for preserving with typical poison based liquid. Porch posts had roof protection. Logs were green, freshly harvest so shrinkage took place. Starting from the beginning and about every 7 years the entire surface was hit with sprayed on then brushed in about 99 percent linseed oil, sold especially for log homes. Name is "Menwood". Examination periodically as to log condition showed no sign of decay, insects, woodpeckers, etc.