Insulation between flat on flat log installation

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Permalink Reply by John Ricketson on September 24, 2009 at 4:52pm

If you are resting flat-on-flat, you are not looking for insulation. You need something to provide a consistent seal between the logs. A log that has it's weight supported along the entire run will shrink, bow, twist, and move differently at different places along the run due to wood density and moisture content. You didn't say if the logs were going to be vacuum-kiln dried for stability because they need to be dried down to 13% or so at the core to get past the twisting phase.

Best suggestion: 1: Make sure the logs are HeartDried in a vacuum kiln. Ordinary humidity kilns only dry the surface of the timber. 2: Use a spline between each course as a solid barrier. 3: Use Perma Chink's Stack-N-Seal 2 between each course. 4: Be prepared to use Energy Seal on the exterior joints in the future to insure a complete seal under all circumstances.

Every foam tape I've ever seen in my 33 years of building log homes either compresses and stays flat or turns friable (crumbles like a cracker) very shortly.

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Permalink Reply by Richard Clauson on September 24, 2009 at 5:02pm

John, logs have been air dried for three years. They will have some seams (vertical) in some of the long runs. I have looked at Stack-N-Seal and Puddylastic but they are sill acrylic/latex based. I do think I will need to use Energy Seal or Conceal on the exterior. I don't like the foam tape either but thought the EPDM gasket might do the job. What do you think?

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Permalink Reply by Tim Bullock on September 24, 2009 at 5:49pm

Richard,
We use Emseal.......I would not use anything else for your application.....free advice and worth exactly what you are paying for it.........LOL

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Permalink Reply by Dave Dikeman on September 25, 2009 at 11:48am

Richard,
Emseal tapes are available in two grades, one impregnated with asphalt (cheaper) and one impregnated with acrylic. They are sent to you pre-compressed with adhesive on one side. Just peel and stick. I suggest using two strips to insure a dead air space for insulation. The Classic (asphalt) tape runs around 20 cents a foot, the acrylic is around 25 cents a foot. It is just one alternative to the Stack-N-Seal (which I would recommend). The Emseal will not crumble on you, although I would still recommend a bead of EnergySeal between each course to insure water from not infiltrating between your logs.

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Permalink Reply by Rick Taron on September 25, 2009 at 4:41pm

You know Richard, there is the good news and some bad news with the flat on flat.
The main advantage is that it is easy.
The main disadvantage is that the wall does not shed water properly. This is what you are working against as you probably know with all the caulking and insulation discussion. You can get it air tight alright, but what about the water in a driving rain?
Your wall will have wide cuts on the butt and right above that log you may have a narrow flattened log which would create a "shelf" where potentially water will sit. Am I right? Have you figured a way not to have these shelves? You could grind and bevel them off I suppose.

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Permalink Reply by Richard Clauson on September 26, 2009 at 8:06am

Rick, I always appreciate your feed back. You ask the correct questions and they confirm or educate me on my endeavor. You are helpful and have an open mind about building. I figure this construction is not necessarily easier or faster. It is just what I'm comfortable with and don't care for the Swedish cope. The possibility of smaller logs over larger logs is viable and probably will happen even with good planning. When this happens my plan is to use a power plane on the sides of flats to have them fit more closely and avoid the shelf. I still plan on maintaining a six/eight inch or larger flat surface and go large to smaller logs as I build the wall; there should not be that much plane work to do. The planing can be touched up with a knife to give it a hand hewn effect. I will not mill the last two feet on the ends leaving them round. These are the tails sticking out beyond the walls. (More hand work to look like a scribe corner). There will be caulking on the exterior of all log seams. Corners on the outside will need caulk to insure no moisture invasion. May caulk inside but not sure yet. At this time I don't believe chinking will be needed. That could change once I see what the wall profile looks like and would replace caulk with chinking.

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