R- value of logs?

[hammerhead 67]

What is a ballpark R- value of different size logs used in exterior walls?

Thanks!

[hemlock77]

1.2 per inch I believe.

[bmurphy96]

R value will vary based on wood species. It is typically around 1 an inch but that is no exact figure. I have seen a table somewhere but don't remember where it was.

Keith

[loghousenut]

Hammerhead, I am supposing you are considering a log home and wondering what the real truth is about logs and R value, and you are trying to sort through the baloney and hype that is out there on all sides of the issue. The subject has been done to death on this forum and the link below goes to one small representative thread. The general concensus is that Skip Ellsworth was right when he said "You'll never be too hot or too cold in a properly built log home". The class offered on this site teaches one way to do it right.
Many of us who live in air conditioning country don't install air in our LHBA homes. Most of us heat by a single wood stove or direct vent propane heater. Your County inspector will approve of the engineered plans that you have drawn or purchase from the association, and he/she won't care about R-value. You probably asked the question expecting a chart that will make it all make sense but I personally think the charts and graphs tend to muddy the water and slow down the process for most of us owner builders.
If you build right and don't use "weenie" logs you'll end up with a home that will allow your Grandkids to brag about how cheap it is to heat. Take the class... I did.

<a href="http://www.loghomebuilders.org/log-size-0">http://www.loghomebuilders.org/log-size-0</a>

http://i157.photobucket.com/albums/t55/loghousenut/Wow/Rooffinally051.jpg

[BigJohn]

Generally speaking, the softer the wood the higher the R-value. Cedar and the pines generally offering among the best R-values. However, R-value does not offer the complete picture. Thermal mass is also important and that is an area where logs triumph over conventional 2x4/insulated homes. The bigger the logs, the greater the thermal mass.

However....R-value and thermal mass is all for naught unless your logs maintain efficient sealing between the logs. Again, this is an area where larger logs tend to defeat small logs. Bigger is better in log home construction.

Of course you may need a machine to lift the logs. Safety becomes a more important issue as well. After it is done however, cannon balls may harmlessly bounce off of your home. An issue we are all surely concerned with?

[hammerhead 67]

Yep! We are going to the January class and I was wondering how logs compare to a 2x6 insulated exterior wall. We want something that is economical to heat/cool and I was hoping we could leave bare logs for the inside walls without having to insulate and cover them.
Sounds like a good 12" + log should do. Im really looking forward to all the details we will be learning about.

What about insulating the floors? It looks like you use joists/beams and lay flooring like any stick built home. My wife hates how cold our floors get on our stick built home during the winter.

Thanks!

[Timberwolf]

That's what in-floor radiant heat is for. Class touches on that, and it's heavily covered in the members section.

[spin05]

here ya go........

every species of logs r-value

http://www.loghome.com/articles/86

[54darock]

I lived in a D log home in Alaska for 4 yrs and we heated the house primarily with a small wood stove, and it was located in the mud room at that. The logs were only 8" thick. We stayed warm in the winter and cool in the summer (not that it gets hot in AK). I can't imagine what it will feel like in a 12" or more log home.

[loghousenut]

I lived in a D log home in Alaska for 4 yrs and we heated the house primarily with a small wood stove, and it was located in the mud room at that. The logs were only 8" thick. We stayed warm in the winter and cool in the summer (not that it gets hot in AK). I can't imagine what it will feel like in a 12" or more log home.

It woulda felt over twice as good with 12" or larger logs. The thermal mass thing that the logs do increases exponentially or something. We have an engineer or three on this forum who can't stand simple old plain english answers that include no numbers. They will take your post as a challenge that needs definition.

OK Peter, I set this one up for you to clarify Hah Hahaha.

[54darock]

Glad to know that there are some engineers that can offer input with their knowledge. It made a believer out of me to live in a "D shape log home" any to experience the warmth of a log home. In my mind there is no comparrision between conventional vs log homes as far as thermal insulation goes.

[StressMan79]

dangit LHN...

yes, thermal mass is one attribute that increases (linearly) with log diameter. There is a limit to how thick of a wall does you much good.

Picture a wall of steel 8 ft thick. Lots of thermal mass, R value of just about what code requires... You'd still be more comfy than a stick built wall, bc that steel stores the heat (heat capacity).

With a wall that thick, (the same thing for normal-sized logs, since the R value is higher) you end up with a phase delay WRT the outside temp. You effectively fight the average outside temp, not the worst. So if you have a 100 degrees @ noon, and 50 degrees at midnight, you have an average of 75 deg. The bigger the wall, the more accurate this is.