ICF House

[pellegrino]

I would think sprayfoaming directly onto drywall would be a bad idea. The way it expands and then the moisture might cause issues. If you were to sprayfoam into the attic I would think it would have to happen right under the roof.

Yes, sprayfoam in the attic goes between the rafters, it seals off the attic and makes it a conditioned space.

[FN Phat]

I just had my attic sprayfoamed a week ago. It makes sense for us because the attic was never intended to be vented and we have our AC unit up there too. Temperatures here haven't been as hot as they usually are since it was done, but our AC unit has been running a lot less and when it does turn on the air is cold from the start. We have it at 76 from around 11:00 PM until 6:00 AM, and 79 during the day. Needless to say, it comes on around two or three times during the day for about five to ten minutes each time and then it kicks on in the evening for about a half hour.

I spayed my attic with blown-in insulation and have seen a big difference. I can only imagine how the sprayfoam would work.

[Xander]

You weren't worried about segregation?

Very impressive building methods. Was the cost of the ICFs much higher than a traditional concrete foundation? You save labor hours from not having to strip, clean, and stack forms. Or was that offset by the labor associated with installing the product?

I doubt a lot of segregation happened. I used pea gravel so there were not a lot of large particles to separate. The overall concrete ends up being denser and cures harder then traditional foundation walls. This happens because you do not remove the forms so it keeps its moisture longer and curses slower which means harder.

The cost is hard to figure directly with just one corollary. The ICF is the forms as well as the insulation. Generally speaking, since you can do it yourself, it costs about the same as paying someone else to pour a traditional foundation with their forms, but then it’s already insulated and the concrete has a higher psi rating.

[FN Phat]

I doubt a lot of segregation happened. I used pea gravel so there were not a lot of large particles to separate. The overall concrete ends up being denser and cures harder then traditional foundation walls. This happens because you do not remove the forms so it keeps its moisture longer and curses slower which means harder.

The cost is hard to figure directly with just one corollary. The ICF is the forms as well as the insulation. Generally speaking, since you can do it yourself, it costs about the same as paying someone else to pour a traditional foundation with their forms, but then it’s already insulated and the concrete has a higher psi rating.

What was the psi of the concrete?

[Xander]

What was the psi of the concrete?

I don't recall exactly, probably a 5 bag mix (3000psi depending on supplier). According to some studies it cures 50% stronger then wood forms. So that would put it in the 4000+ psi range.

http://www.builderswebsource.com/techbriefs/about_icfs.htm

I've had to drill and chisel through it a few times and it definitely feels harder than other walls I've worked on.

[FMCoug]

We thought really hard about going ICF when we built our house in Texas. We finally elected to go with 2x6 walls and the full envelope Icynene foam insulation as it was a lot cheaper. If I were to do it again and KNEW I would stay there forever, I would look hard at ICF plus GeoThermal HVAC.

[FN Phat]

We thought really hard about going ICF when we built our house in Texas. We finally elected to go with 2x6 walls and the full envelope Icynene foam insulation as it was a lot cheaper. If I were to do it again and KNEW I would stay there forever, I would look hard at ICF plus GeoThermal HVAC.

My ol' man went with a GeoThermal HVAC and it is damn impressive. If I were to ever stay in one place long enough, I would definitely go that route.