Why Build an ICF House

[scgargoyle]

An ICF foundation is no different than a regular poured one- 8" or so of reinforced concrete. It just happens to have insulating foam inside and out, Although the ground is fairly stable in temperature, the upper 4' or so varies more, plus you have the part of the foundation above grade. In some northern areas, the ground can freeze 4' deep or more. That's 32 degrees- pretty cold.

Where we are building in SC, my friend's uninsulated basement was about 55 in the winter, and 75 in the summer. I could reasonably live in that temperature range without heat or A/C, which is why some homes are almost completely underground. That moderate temperature range is why I'm still undecided about ICF- it hardly seems worth it to have an insulated basement.

 

[BobRip]

An ICF foundation is no different than a regular poured one- 8" or so of reinforced concrete. It just happens to have insulating foam inside and out, Although the ground is fairly stable in temperature, the upper 4' or so varies more, plus you have the part of the foundation above grade. In some northern areas, the ground can freeze 4' deep or more. That's 32 degrees- pretty cold.

Where we are building in SC, my friend's uninsulated basement was about 55 in the winter, and 75 in the summer. I could reasonably live in that temperature range without heat or A/C, which is why some homes are almost completely underground. That moderate temperature range is why I'm still undecided about ICF- it hardly seems worth it to have an insulated basement.

By insulating the basement it becomes part of the thermal mass of the house. This keeps the rest of the house at a more stable temperature and allows you to downsize the heating and cooling system. My summer cooling cost are very low. The first ICF house my builder built was ICF in the basement only.

 

[czechsonofagun]

From what I have read, Bob, people who went with ICF for the basement typically wish they build their whole house with it.

There is something about sleeping in brick and mortar house, at least for me, European house feels better than American stick built house. Maybe because I grew up in apartment house with ceilings 12' and outside walls 3' thick?

First balcony on the left, but my bedroom was on the other side - total about 100 square meters for 4 people.

 

[Bill Barrett]

By insulating the basement it becomes part of the thermal mass of the house. This keeps the rest of the house at a more stable temperature and allows you to downsize the heating and cooling system. My summer cooling cost are very low. The first ICF house my builder built was ICF in the basement only.

I'm with you Bob, In my area 30% yes thats 30% heat loss is through the foundation.

 

[dmccarty]

Fine Home Building had a story about that house and why it didn't burn when everything else did. They talked about what he did specifically so that it wouldn't burn when he built it. From what i remember, he made the stucco on the exterior over two inches thick. Average for a house is in the half the three quarters of an inch thickness. He had special windows installed. I think I read that they were quadruple pained for maximum R value, but it might have been something different. I'm not sure about the windows. He also had special doors installed.

The main thing that he did that he was credited with saving the house is that he didn't have any roof vents. The reasoning is that vents do not cool an attic, and only allow air flow through the attic to eliminate condensation. He made the attic air tite, which didn't allow the fire to get into the house. There was nothing to catch fire, so the house was spared.

This was the first time I ever heard of not using roof vents on a house. Since then, there have been quite a few articles on doing this. With the advancement of spray in foam insulation and its popularity growing, it's also becoming more and more commont to insulate the roof of the hose and not the ceiling to give the house a total shell of insulation. Apperantly it's cheaper to cool the attic from the outside temps then it is to cool the ceiling from the attic temps.

Eddie

The house also had very small roof overhangs. I think the roof was also metal or a cement/clay product so embers would not start a fire on the shingles.

Lsitburek talks about sealing attics and crawlspace, which sounds crazy, until you listen to what he says. I really wanted to seal our attic, but I figured it would be big battle with the code inspectors, so I just did not pursue the issue.

Later,
Dan

 

[dmccarty]

As I said earlier in this thread, we really looked at ICFs but in the end, the money said to build with 2x6 walls with an R value of 25 or so. Since we wanted lots of big windows, it did not make money sense to build with ICFs, and then put big holes in the walls. Not sure it made sense to use 2x6x either.

Every major room has a 8'x6' window with the exception of the kitchen which has a 8'x5' window. The living room has an 8'x5' and a 12'x6'. There are a LOT of BIG holes in our walls.

The house is 2,425 sf with 10 foot ceilings.

I paid the power bill this week. I have tracked every power bill we have had since we built the house. We did this see if the design and construction worked from an energy, and thus money, perspective. It has. Our power costs our the same or less than our city house which was less than half the size of the current house.

We heat with wood so the only time the HVAC is used is during hot weather for AC or if we run out of firewood in the spring. This makes it somewhat easy to figure out our HVAC cost.

The last bill period was mostly very hot and humid. Not spring but summer weather. The power bill was $135. Which happens to be the monthly average over the last couple years.

The first few months of 2011, with no HVAC, the power bill was around $115-120. Last December was worse since we were home, had visitors, and used the oven quite a bit. That bill was $150ish.

Our AC bill last month was maybe $15-20.

The worst cooling bill we had was $221 last summer when it was 100 degrees day after day. That was an unusual bill. We ran out of firewood one year and had to turn on the heat and the bill was about $175.

Go back to Beppington's numbers. Our worst case heating and cooling bills are $100 a month which does not happen often. The extra cost to use ICF's just does not make money sense from an energy usage perspective for our house. Beppington's numbers are also low since he was just looking at the loan cost and not what the money could have earned if invested.

If we live on the coast, and could get hit by the full force of a hurricane, then we would have built with ICFs. Not for energy but to be safer in a storm. :laughing:

There is a program called RESFEN developed by US government. I mentioned it earlier in this thread or the other home building thread that has been active recently. This program models your house based on the size and number of windows, their performance numbers, size of house, type of heating and cooling, energy costs, house location, etc. I used it to evaluate the windows we were looking to buy. The programs energy usage and cost for heating and cooling were pretty danged close to what we get in the house.

Later,
Dan

 

[Putter]

Our basement is ICF. When I was doing the wiring in the walls I used an electric hot knife with a loop tip. It cut/melted a pathway very quickly then I used the pieces that came out to fill in on top of the wires.

Fish, this is what I am planning on my ICF foundation. Does the wiring in the wall require a protective shield? How deep did you place the wire? Thanks.

 

[beppington]

Lsitburek talks about sealing attics and crawlspace, which sounds crazy, until you listen to what he says. I really wanted to seal our attic, but I figured it would be big battle with the code inspectors, so I just did not pursue the issue.

My friends did that in '06, & it passed code. They sealed the attic & installed the insulation up against the bottom of the roof sheathing. During our FL summers, their attic is only about 10 degrees warmer than the air conditioned living space below.

 

[beppington]

Our power costs our the same or less than our city house which was less than half the size of the current house.

Are the power rates the same?

 

[dmccarty]

Are the power rates the same?

Yes and no.

Same power company so the rates would be the same. So that is the yes.

The no is that the rates are higher now compared to the smaller city house. Which means the new, bigger house is that much more energy efficient compared to the old house. In the city house we were always cold during the winter and a bit hot in the summer. The new house is much more comfortable. :thumbsup:

I think our biggest energy usage is the hot water heater, computers, clothes washer and dryer. Best I can tell the water heater cost $20-30 a month. The washer and dryer run constantly because of the kids.

Later,
Dan