R value of solid wood walls

[drandazzo]

If soft wood, such as pine, has an R value of approximately 1.5 per inch, will a solid timber wall 6" thick remain at an R value of 9 or does that change when the interior temperature is maintained at between 65 and 70 degrees?
This situation is typical in a log home type construction. Any information would be helpful.
Thanks,
Don

[Toolwhore]

Re: R value of solid wood walls

drandazzo;

I've worked on many log homes and i can tell you that they are very inefficient as far as heating. Most of the logs we used were 12 to14 in. dia. in very large houses (6-12,000 sq. ft.) all top of the line hydronics and the heating bills were astronomical compared to a stick framed house of the same size. I'll see if I can find some of my log books tommorrow and find you some numbers.

[Firehammer]

Re: R value of solid wood walls

I agree with toolwhore on this one. Very inefficient insulation.

[phillip]

Re: R value of solid wood walls

I dont know what to say on this


but here is an old report

http://www.oldvaloghomes.com/EnergyE..._log_homes.htm

[Firehammer]

Re: R value of solid wood walls

I stand corrected...

[Dick Seibert]

Re: R value of solid wood walls

Phillip:

Thanks for the link, I'm planning a log home and am getting ambiguous answers from an architect who does nothing but log homes, I'll send him the link.

[Toolwhore]

Re: R value of solid wood walls

That is very interesting material. I have many reservations on the validity of some of the statements though, as this was the Log Homes Council's view of a report.
Then again, my statements were rather bias also, because I was basing it on my 12 years experience of log home construction of "Show Homes" of size and design that far exceed anything considered average. Log on log with saddle notch corners of the type people usually think of when they hear the term "Log Home". Nothing like what was described in the log structure in the article. Most people build a log home for the "look". I'm guessing that most people couldn't tell which one of the test buildings was the log building from 100 feet away, when built as described.
I am in full agreement with the thermal mass concept if built in such a controlled manner, but I live in the real world and log home designs are more often than not, built with design (The LOOK) in mind first, and efficiency second.

Dick;

I just can't picture you in a 20x20 one room cabin with 7 1/2' ceilings, 1 door, 4 windows (totaling 43 sq. ft.), painted off white on the interior and brick red on the exterior. What happened to the log house you were supposed to build? LOL!!!

[phillip]

Re: R value of solid wood walls

Thanks for the link to the very informative article on insulating qualities of various types of construction. We are contemplating a solid timber 6 x 12 inch square log home and there is a lot of good information in the article.
Don

Now this is the type of log home the article addresses tongue and groove log possibly with a rubber gasket http://www.lincolnlogs.com/buildingsystems.html


while I would not say the article adresses houses with freshlogs and chink

************************************************** *******
Dick might also have a lean to addition on his house like this one

http://philspages.com/06_Pic/images/1024a.jpg

[78_GMU]

Re: R value of solid wood walls

My father had a log home built for his retirement and has lived in it for over ten years. The logs are tongue and groove. I calculated his heat loss/gain and then the expected annual energy cost using a value of R-7 for the log walls and ignoring the "energy mass." His actual annual use was well short of my calculations. The biggest problem he has is with the insects who love to bore holes in the logs, not his energy bills.

Here is a link to a paper on thermal mass for concrete walls, the same principles may apply to thermal mass of log walls, it could be worth a read...

http://www.huduser.org/publications/...VACSizing.html

[bkerley]

Re: R value of solid wood walls

78 GMU

My mother's log (t&g gasketed) home is the same way. Hers is roughly 10k sq ft and her utilities are lower than mine in 2700 sq ft (1894 balloon frame construction) they run about the same as a newer 3000 sq ft frame home in this area. Cost per ft (utilities) only. Maintenance is an issue with termites and powder post beetles. She loves it. I don't know if I would want to build one in a coastal area though.

We are working on "restoring" one now but we won't be using the traditional chinking. We are planning to use perma-chink instead. This won't be a live-in. It will be used as a recreational out building. The original footprint was roughly 18' x 20'. It is now around 30' x 30' and we hope it won't keep growing. HO changes plans fairly regularly. T&M

[Dick Seibert]

Re: R value of solid wood walls

BKerly:

Hers is roughly 10k sq ft and her utilities are lower than mine in 2700 sq ft

That's not a misprint, your mother's log home is really 10,000 square feet and the utilities are less than your 2,700 square foot home? There are several T&G gasket systems running from bulb rubber gaskets to "V-ing" and scribing the logs with fiberglass in the "Vs", do you know which system she has? If correct, you're pitting my plans back on track!

[aerieandy]

Re: R value of solid wood walls

While living in ID and Wyoming I was a Lead and built and worked on many log homes. It is my belief that many of the same principles as conventional const. decided how efficient these homes were. The swedish coped houses were pretty good which reduced settling, but also increased the amount of wood at the log interfaces (vs saddle coped on the corners and synthetic chinking along the horiz. seams).
The best by far were cedar logs with t&G and two different types of taped gaskets,one butyl on the exterior joint and a foam tape in the interior.
The "old timers" claimed the cedar was a better r-factor because of lower moisture content and they ALL swore that traditional calc methods don't work for the mass of a well built log home.

For what it's worth
Andy

[Toolwhore]

Re: R value of solid wood walls

Dick;

How big of a log home are you thinking about? ( just curious )
The "V-ing" you referred to, is called "full scribe" or "Swedish Cope". It is the most energy-efficient of the "Log on Log" style of building. That said, it is also the most labor intensive which = $$$. I'm not trying to discourage you in any way. I think well-built log homes are pieces of art.

[Toolwhore]

Re: R value of solid wood walls

aerieandy;

I believe I know who you are now. We've worked on some of the same projects in Jackson, if I'm not mistaken. You must know Peter Kurt and Adrian ( Mad Wolf Log Homes ) I have also worked with Hal Staley, Tennesin & Ankeney, Peak Builders and a few others. I was the guy known as "The Finger". Small world, aint it!

[davenorthup]

Re: R value of solid wood walls

The only log structure I have built was Swedish cope. Labor intensive of the manufacturing; but a snap to assemble. 2 guys 3 days 20 x 30 w/only human power. for the walls. The foam gasket is great for stopping air infiltration. I should mention that most kit logs are computer milled and fit together very well. Chinking is what I call labor intensive.

One thing missing from the energy calculation discussion is the solar heat gain. I have spent many a cold nights in a log cabin with no fire b/c the heat emitting from the logs was enough.

B - log cabins here have been around for ever in wet climates here. The key is keeping them sealed and big overhangs.

Tool - I bet we may have some mutual acquaintances from Jackson as well. I have quiet a few friends born and raised in Hoback Junction / Teton Village area. A very small world indeed.

Is there a story behind 'the finger'?