Log Homes

S Davis

What do you guy's figure for wall R-values in log homes? this job will have 14" Douglas Fir that will be scribed and have a tight fit not chinked and will have a minumum 4" thickness.

S Davis


Apex Radiant Heating

Ken_8

By any measure...

Log Cabins are pure romance with poor to extremely poor energy factors. The energy factor for fir is around 1.25/inch. Assuming a full 14" thick and no curved surfaces - you'll be lucky to have R-14

Energy efficiency in a true log cabin are oxymorons.

The only source claiming the wonders of energy efficiency of log cabins seems to be the company that sells them.

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Big Idahoan

r-values

of most log homes i've been told are around a r-12 we have done radiant in several of them. we use warmsource from rehau to do are heat loss calcs. and we've always needed supplemental heat a majority of the rooms especialy w/hardwoodfloors but ask the log manufacturer.

marc

be fair

to the heat loss, we figure the depth at r-1 / in. plus deduct for the curve of the log. about 20-25 %. so far no problems. have you been back to a log home 5 years later and felt the drafts thru the logs. scary. marc

Mark Hunt

Ken is correct


as usual!

One of the largest contributors to heat loss is CONDUCTIVE heat loss. Make the logs warm and they will become heat syphons just like studs in a stick built home, only magnified.

Heat goes to cold, period. Logs may not be a great conductor, but they are a better conductor than dead air space.



Mark H

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Mark Eatherton1

Go cautiously...

http://www.eere.energy.gov/consumerinfo/factsheets/ca8.html

ME

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Mark Hunt

Good article Mark


but I notice that they only look at heat transfer as a "one way" phenomenon.

"Storing heat energy by day and releasing it into the home at night". Well you and I both know that tis happens 12 months out of the year. So in the summer, the same thing happens. Heat goes to cold!

Conduction sucks!!!!!!!

See you in Boston! I owe you a couple!

Mark H

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S Ebels

I figure

R-value of 1 per inch of thickness and deduct for curved logs. Usually averages about a 30% reduction. (ouch) Log homes can be made, and kept airtight with good sound construction and diligent maintenance. And I do mean diligent, unending, constant, maintenance.

A lot of grief down the road can be eliminated by educating the customer up front about maintenance on a log structure. As someone else posted above, a log home can get real drafty after a few years of settling and movement has occured. And they ALL do it. Make sure your customer understands what you are designing for and that they are in for a lifetime of maintenance in order to keep their house in that condition. The log home builders HATE it when I do that but it's the truth. I have sat right at a table with builder and customer and brought up the subject and the builder ususally gets that "deer in the headlights" look on his face. Some have told me I was no longer going to be recommended to their customers, but hey, my rep is on the line here too. I have never gotten in trouble by being forthright and honest about system performance. Many customers on the other hand have thanked me profusely for bringing it up. They are who I work for, not the builder.

Weezbo

logs are poor insulation.....

up to 12"3 sided you can insulate (chinkseal)and go tenatively 1 R per inch............tapered logs 14->28" you have diminishing returns heres why..as the logs dry even turned tapered "(Dry seasoned)"the things twist turn and check and crack in place for Years...they are extremely expensive to heat...pay for a thermal picture of the place in winter..:) that will definitely give you a clue as to just how impossible it is to provide you with anything other than a guess...workmanship is everything with logs by the way..the things settle and expand. your best to steer off of them unless your rather handy with tin knocking...ive done alot with boilers however they can always suddendly develope some new pain in the brain...totally unrelated to the original installation. Air thru hrv's and a boiler would be the place to start with some balance of the humidity...many people have a coffee kettel on almost constantly or a water pot boiling if they have wood heat. without a vapor barrier you can make a relatively certain educated guess where that moisture is locating itself..

dconnors

Actually ther e is a govt. study......

i read a long time ago that a 8" log home consumed the same energy during the shoulder seasons and less during the depth of winter and height of summer. they attributed this to thermal mass as there was no other explanation. the ceilings and gables on each house were 6" insulation. both were 1000 sq. ft.