[Cob] tree poles for cold climate insulation

[Amanda Peck]

Try this--inexpensive directions, not plans:

http://www.alaskacabin.net/

Vertical logs, held together with landscape screws or lag bolts, guy swears 
that it can be made with green--peeled--logs, and is warm and snuggly.

We tried it last summer.  Not yet finished, of course. But with poplar and 
mixed woods from my land, plenty of shrinkage and cracking, I'm having to 
replace about half of the chinking I put in.  But it's sturdy.  We put the 
logs between bottom and a top plate.

The pictures I've seen--in Mother Earth News and another one of those 
magazines--backwoods home maybe--woman built it twice--it burned the first 
time, make pine logs look tight and wonderful.  And the guy here who had a 
sawmill rip parallel slabs from his logs so they fit together beautifully 
might have had the right idea.

If you've got the wood, and the space, you could make a double layer of 
logs, screwing them both between layers and along each line.  Landscape 
screws are pretty expensive, but they come in lengths between 4" and 12" 
long.  They also put a metal, cold-conducting bridge into your walls, as 
does rebar.  We put in two to the previous log, one into the bottom plate, 
nails from the top.   But they will go into a pre-drilled hole, can easily 
be countersunk--three heavy-duty cordless drills would be nice--one with 
each size bit, one to screw the guys in.  Hack saws cut them with some 
effort if they can't be backed out.

There's been a lot of talk about whether "insulation" or "thermal mass" is 
better, whether they both work, and so on.  Thermal mass will not be better 
if you expect to go to a house for the first time since July at Thanksgiving 
and expect it to be warm quickly.  But it's very good if you're keeping the 
place warm--take a good while to cool down if you leave for the weekend--and 
probably to heat up if you come in for the weekend.

Rob Roy has been experimenting with cob in his cordwood masonry, and he 
likes double walls with insulation in between.  He's in upstate New York 
(more than cold enough for me!) and uses the construction for saunas, which 
might well illustrate the temperature differential you need in Alaska 
winters.  Searches will give you tons of references.



..................
Ryan writes:
I am looking into possible alternative homes for a house I want to build for 
myself in south central Alasak. Cob intriugues me, but as I have read it 
isn't great for places with a lot of constant cold weather, whcih we 
certainly get. While straw bale insulation has been mentioned I am leary of 
it since becuase of it's extreme bulk when including the cob walls, and 
because it would seem to eaken the structure of a cob house with it's 
discontinuity between the two walls. This is a worry in to me because we get 
earthquakes up here. it would seem to me that two seperate wals would not 
flex together during a quake, and be morelikely to shear.  I was wondering 
if tree " poles" placed vertically could be used as insulation? That is 
trees of 8 or so inches in diameter placed vertical in the foundation with 
cob surrounding the pole walls both inside and out. The poles placed 
vertically would allow the flexibility of design that cob offers, but would 
this give the buffer needed to prevent heat from being drawn out of the 
house and/or cold drawn into the house? If so should the poles be places  
touching each other or can there be some space between the poles to allow 
the cob to connect from one side to the next? My thought were that as close 
together as possible, or slightly overlapping. and to give contiunous 
support throughout the wall, from one side to the next to put some type of 
"rebar" through the wood connecting to each side pointing in various 
directions with bends in the bar so that it doesn't move in the cob should 
the wall move. Shoudl the rebar be the metal type we all know or could it be 
something else such as small branches. If you think of anything else for 
rebar that would be great.
thanks.
Ryan

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