Originally Posted by simonkenton7
I know the charts give that low R factor for wood. However I believe that is not accurate, at least when you get up to a log that is 6 inches thick.
I have been in frame houses in this same environment with 2x4 stud walls and R 13 and my house is at least as snug and warm, if not more so.

However if I were building in NW Montana, [which is my home state] I would certainly go with thicker logs.

My houses are all in N. Carolina and Georgia.


Well God sure didn't make all logs alike, R values will vary with species and it's my personal belief the region the log comes from can make a substantial difference.

Hardwoods have half the R value that softwoods do and the reason isn't a mystery.

It's the density of the wood.

Softwood logs are very 'fibrous' and are known to store heat.
I dug up this image to illustrate what I'll attempt to explain.

[Linked Image from teara.govt.nz]

This is a cross section of a pine viewed through a microscope.
Each growth ring is made up of cells that deliver water and nutrients up the tree.
They are like tubes or straws, the wood that develops later in the season (dark red areas) is somewhat void of these cells or 'tubes'.

The center, or heart of the tree is pretty much dead too, this process no longer occurs, the core is hardened off.

When a log is properly dried these tubes in the outer growth rings (sap wood) are left hollow and hold air.
All this air is what gives softwood a higher R value than dense hardwoods.

The air retains heat and gives the log a warm feeling that you don't get from a sheetrock wall in a stick framed house.

Of course this works the opposite if the log is to become cold, it takes forever to warm all that air deep inside a log.

My theory for obtaing a better R value log has been to buy coastal timber from Oregan. The growing season is crazy long in the coastal areas and there is way more precipitation, this results in the growth rings being twice the size of the growth rings in logs I am able to buy in Montana.

More fibers, more air, more insulation?

The coastal logs are also much lighter weight with these less dense growth rings compared to other logs I've had to deal with. That's alway a nice feature when you have to move them and roll them and adjust them endlessly while building a log home.

Is there any fact to my feelings about R value with coastal logs?
WTF knows, it's how I see it and I'm stickin' to it.

A couple down sides to the coastal logs I've found is they aren't as strong when used in a horizontal application such as ridge beams or purlins, I use dense Montana logs in those situations.

The big ones are spendy.
The big lumber companies basically own all the logs.
They desire these prime home building logs too. They spin them to cut veneer for making plywood.

Its costly to buy something from a company that has as much or more need for it than you do.