Why Build an ICF House

[magicheater]

If you live in a region where autoclaved aerated concrete is produced/distributed, you have a much more elegant solution than ICF.

Autoclaved aerated concrete has both mass and insulation built in through the fine pores throughout its structure. The blocks can be cut with the same equipment used for wood working, taking account that lots of dust is generated with power equipment. One builds walls much thicker than with regular concrete. Below grade I would not use AAC, there is no need since with just 2" of extruded insulation on the outside, there is minimal heat loss through regular concrete.

Inside the shell, one can do interior walls in AAC block too, just thinner. In areas like bathrooms, a cavity wall can be built to conceal all the plumbing. There are core drills to drill holes through the block and it is much faster than on regular concrete.

The acoustics of a home built with AAC or rammed earth are in no way comparable to any stick built home. I have not yet experienced a SIP home, but it will be damped too, but light rigid panels also make good membranes to transmit low frequencies.

I was in Weil Am Rhein in Germany when hurricane Lothar swept in on the 26th of December 1999. Winds peaked at over 200mph. Thousands of square miles of forest was blown down in seconds. A "few" buildings had their roofs blown off, generally in 1 piece. Many older buildings lost tiles from their roofs. The 3 storey home I was in lost about 15 tiles from the roof. Not a single window broke and the air was not filled with debris, like what one sees here in the US in tornados.

A very informative post, thank you.

 

[westcliffe01]

SafeCrete.com - AAC Internet Sales / AAC Products / AAC Information / AAC Construction

Biggest AAC company in the USA. Licensed from the patent holders in Europe I believe (Hebel). They are based in Georgia. Every now and again they have some awesome pictures of their homes built with their product as the only homes standing after wild fires destroy the rest of he subdivision.

They have videos on fire testing followed by hosing down like firefighters will always do.. Eye opening results. http://www.safecrete.com/aac/videos/AAC Fire Test.MPG

Interior climate example http://www.safecrete.com/building/Thermal brochure.pdf

Picture of an AAC home that survived a fire where no other did:

It is not a silver bullet, but the manufacture has a "system". All the tools are available to make the building process painless. Mini cranes for hire. Saws and coring drills. Special grout (not mortar) for bonding the blocks. Jumbo blocks all the way up to 12x24x48 which are handled with aforementioned mini crane makes the work go fast.

Unfortunately, no representation anywhere near where I live. And at some point, the cost of transport will get significant.

 

[EddieWalker]

Picture of an AAC home that survived a fire where no other did.

Is this the house from the Southern California Firestorm in the Late 80's?

Eddie

 

[wedge40]

This is off topic a little, but as I read through this post I was curious of what ever happened to building with the steel 2 by material.. They were shaped like 2"x4" or 2"x6" but made out of metal? Seems like 10 years ago they were all the rage and now I don't see them anywhere.

Wedge

 

[westcliffe01]

Steel commodity price drama of the past few years made it too expensive ?

There used to be many pictures of the California house online including close ups, but I can no longer find them.

Here is a better quality one

Apparently it was Laguna CA in 1993.

"The owner of this mansion shipped in the autoclaved aerated concrete material from Europe. Over 360 families lost their homes to this 1993 fire. Subsequent investigation concluded that nearly all of those structures burned from the inside out. Meaning the wall material of the homes transferred heat and the interior materials combusted (wall paper, insulation, drywall, 2x4 furring strips, etc.) AAC is non-combustible and restrains heat transfer, saving property and lives."

 

[EddieWalker]

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

 

[Bill Barrett]

Don't want to get into cost factors, because I don't know for sure on all trades.

As a HVAC and plumbing contractor, they didn't cost any more to do than frame, if there wasn't much plumbing in the outside walls.
I've done more than a few ICF houses. I even built one myself.
May even be less than frame because of smaller equipment!
Very active families that are in and out of the house all day really in practice don't need HVR units. Most folks that fall in that group don't even run theirs.

I'm 70 miles south of Chicago, very hot, very cold, lot of wind.
Doing heat loss/heat gain on all the ICF's that I did, it was a huge difference.
One house we did was over 4000 sq ft, I put a 50,000 BTU furnace and 2 ton AC.
Home owner and general contractor wanted over twice the size of equipment.
I told them I'd change it if it didn't work.
The day every contractor was there finishing up, was mid 90's and humid as ****. With the house full and everyone in and out all day, I had the house down to 68 degrees, that tells me the 2 ton A/C was to big!
Another one we did was blower door tested by the electric company, it was the best test they had ever done.

Also I would disagree that there isn't a migration of heat between the core of the forms and ground.
Not too sure Reward Forms Co. proved that.
I built a house for my daughter, we got the ICF foundation in in the fall with just the deck on. The crawl never froze all winter!

One thing that is a pain on some forms, there isn't any nail strips on some
outside or inside corners.
Not very handy for trim work, I think most companies have solved that now.

 

[JB4310]

I don't get the need for ICF foundations deep in the ground, i thought the ground was a good insulator. Seems like a good place to save money on even if you were going ICF above ground.

JB

 

[beppington]

If somebody could tell me: I generally understand ICF walls, but what's an ICF foundation?

 

[JB4310]

If somebody could tell me: I generally understand ICF walls, but what's an ICF foundation?

I see you are in FL, but in areas that have full foundations/ basements it would be the first 8 feet of wall, mostly below grade. You need to get below the frost line, some may only go 4 feet and have a crawl space or a slab on fill. But most homes have full basements.

So that foundation would be built using the ICFs

JB

 

[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