That's actually a caveat I have to add to log building, which I think Skip (at least in my class) was little glib about.

Keep in mind this is not based on actual experience, and I'd love to hear my theory disproved.

Log Buildings are good insulation, if the logs are thick enough, but not great.

If you assume about R1 per inch and a 12" diameter log you have a Maximum of R12...at the thickest point. The log is usually round, and worse, you have those mortar chinks backed with insulation. I'd be amazed if you could get R-10 out of the chinking. There is a lot of chinking surface.

The good news is that if you live in a climate that's mild, the thermal mass of the log structure (which can be thought of as the time it takes for the cold to penetrate) can accomplish wonders by smoothing out the highs and lows. So if the average temp ( in degree hours) is ok, you'll need only mild heating.

The bad news is that if you live in a part of the world where it gets cold, and I'm thinking daily highs that are sub freezing for weeks on end (if you think ice-fishing is normal, snow sticks and accumulates for several months, your foundations have to go 3+ft down to avoid heave, and you've driven your car across a lake, you are there) then the thermal mass becomes much less important, and the R value becomes critical.

As I mentioned above, the R value of the walls is no great shakes (unless you have massive logs). Certainly it's lame compared to a modern, well insulated, house wall you'd build in that sort of climate. (R20+, and excellent sealing)

Now this isn't a deal killer for log construction. If you can save a lot of money spring and fall, a couple of weeks of high heating season won't kill you, especially in smaller homes. It helps if you wear a sweater too and, don't mind a house than can get a little chilly once the heater turns off.

But is is something to bear in mind if you build in places with serious winters.

Or you can do like people who live in those old large (uninsulated and not really heated) homes in europe and elsewhere, and retreat to a heated subsection of the house in winter.

Interesting article, Spin. Thanks for posting it.

Fred, I'll be interested to hear any discussion on this-- though for us it's a moot point since we built with large logs in a southern hot summer/cold winter climate with good passive solar opportunities, and oriented the house to take good advantage of winter sun and summer's prevailing breezes.

Sara
:D

The other point is that heat flows *both ways* for you southern types.

Of course a lot can be accomplished with landscaping too, good shade trees and windblock plantings ( or in warm places wind directors) can do wonders for your microclimate.

At the risk of bringing the wrath of the Ellsworth's upon my head, has anyone insulated a log home? While it might compromise some esthetics ( and I suppose, the manageable risk of condensed water, bugs and animals), adding some insulation on the outside of a log structure might be very helpful.

There's lots of log structures in Scandinavia and places like the Ottawa Valley that were later "covered up" with stucco ( and close relatives), or boards or what not.

Some times for esthetic reasons, Swedish manor houses often wanted to look like stone structures, for instance, and in the Ottawa valley settlers wanted to make things less rustic too, but also I would assume to protect or better insulate.

I suppose one could insulate inside too, but then you "lose" the mass.

Does anyone know of a link to a R-Value table for species of Wood?

Oops, found one... http://www.loghomeliving.com/document_display.cfm?document_id=86

Ellsworth,

This is a late question, but are there any other benefits that you (anyone) knows of when building under type IV vs type V? I was thinking of code-issue benefits, but any would be good. Does it play a role in property assessment/insurance rating?