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Chuck Morrison
7th December 2006, 08:52
In a comment of a different thread I mentioned building a house with PerformWall, an insulated Concrete Form (ICF) made of cement and recycled styrofoam, ie. polystyrene. Since this is a type of ICF that not many are familiar with I thought I should show what it looks like in use.

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The above photo shows the aparatus we used to move the ICFs, which weigh 200 lbs each. We mounted an engine hoist on the back of a 1949 Studebaker truck and were able to move and place up to 4 forms at a time. We used just over 100 forms for the outside walls. We found that the hoist, mounted on the truck, a tractor or by inself is invaluable for moving and placing heavy objects.

The forms come in 10 foot lengths and are available in 15 and 30 inch widths. The ones shown are 15 inches wide and 12 inches thick, but they come 8 and 10 inch thick as well. The holes are 6 inches in diameter and when lined up properly form a pattern which ends up being a steel reenforced concrete waffle surrounded by 3 inches of form for the 12 inch variety.

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This is the application we put the forms into. It's a 40 foot diameter circle with door and window cutouts. I cut a bevel on one side of each form with a chain saw to allow a close joint when placed in the circle. I also cut the forms in half to make 100 lb. 5 foot sections. This allowed me to actually move them into place by hand. They were then glued to each other with a foam glue and stapled (large steel staples) until they were cured. I used a face mask to keep from inhaling too much cement dust.

These cost $45US each, which doesn't make them particularly cheap. However when you compare that with the cost of studs, sheathing, insulation and siding it's not too bad, especially if you just finish them off with stucco.

Overall, I believe these forms are a good choice for buildings with curved sides. They allow a flexability that is difficult to achieve with standard building materials, even other types of ICF, that assume flat straight walls.

Rob Beckers
7th December 2006, 09:51
There's a material I've not seen before...
I'm not sure I fully understand how you build with these: Do you fill the holes with concrete, just like ICFs? How does the insolating value stack up compared to regular ICFs? How are they more flexible than regular ICFs? I'd think that cutting out windows would be similar in regular ICFs, just that you'd have to temporarily block the underside of the cut-out channels when pouring concrete in them.

-Rob-

James Jarrett
7th December 2006, 14:11
My wife and I looked at that as a building material for our house. We decided it was too hard to work with (for us) and did not quite give the thermal properties we were looking for.

Right now we are looking a thermasave panels. I like the cost (for what you get) and the ease of use. Check them out at:

http://www.thermasave.us/

Their earthquake characteristics are scary good and their thermal properties can be pretty impressive.

They are not cheap, but like you said, factor in studs, sheething, etc. The price is actually quite good. In fact it came out about the same as local straw bale construction.

James

Chuck Morrison
8th December 2006, 07:44
There's a material I've not seen before...
I'm not sure I fully understand how you build with these: Do you fill the holes with concrete, just like ICFs?


Yes, They are ICFs, just a different way of making them. This kind has been in use in Europe for quite a while.


How does the insolating value stack up compared to regular ICFs? How are they more flexible than regular ICFs?


I'm assuming you mean insulating. This is a difficult subject because R values, as typically used don't take thermal mass into account and so the insulating value of walls like masonry, rammed earth, adobe and these forms look deceptively small. For the 12 inch walls normal R value is around 19. But functionally appear to be around 32 for my climate zone. see this link (http://www.rastra.com/therm_perf.htm) .

By more flexible I mean that you can make odd shapes, like curves or circles with them that are difficult to do with ICFs that lock together in either straight lines or 90 degree angles.


I'd think that cutting out windows would be similar in regular ICFs, just that you'd have to temporarily block the underside of the cut-out channels when pouring concrete in them.


Yes, exactly. Lest you think I'm totally pushing these things as some kind of super green solution, it's not. Check out this link (http://www.crockerltd.net/Rastra%20Bad%20Vibrations.htm) for a criticism of the greenness of it.

I was planning to use rammed earth, since the soil here is just sand and with a little amending would ram pretty well. After some testing I decided that I didn't have enough endurance to pull it off. These are heavy, but nothing compared to that much dirt.