Why Build an ICF House

[rgood]

I think that's a good question - And obviously there are lots of ICF houses with windows on the S. side - So, Why build an ICF house?

1. I used to live in Germany and almost all of the houses are concrete there - And many of the people there now live in their grandparent's house. For many people a house is also an investment, so why not invest in something that will last that you can either sell or give to your kids or grandkids. If you go to Ireland you'll see all kinds of stone houses that are 400 years old. The obvious rebuttal to that is "How long are you going to live?" But still, it'd be nice if Grandpa left something for somebody.

2. ICF houses greatly reduce jet noise, road noise, train noise etc - May not be an issue, but might be depending where you live.

3. Do ICF houses cost that much more? Most web sites say 10% more - My builder says 5% more - I'll let you know.

4. Insurance cost is reduced.

5. In a tornado, the roof normally flies off and then the walls fall in. If hurricane straps are used and a hip roof is used, your roof might stay on - If it doesn't stay on, all you have to replace is the roof. Additionally often times tornado damage and deaths are caused by a flying board or piece of metal - Which will go right through siding and sheet rock, but won't go through an ICF house.

6. Even with windows in the house, your heating/cooling bills are greatly reduced, Because the concrete draws from the heat or the coolness of the ground.


What are your thoughts?

 

[slowzuki]

Number 6 isn't true, it is just well insulated. The extra mass in the outside wall slows swings only slightly, and its not connected to the ground well enough for the ground to play a role.

 

[rgood]

Slowzuki - I checked this out and you are right - It does not have to do with Ground mass, yet it is correct that most studies show ICF houses to be 20% more energy efficient. Thanks for the feedback.

 

[BruceWard]

I researched ICF a few years ago. I bid out the same house plan for 2x6 framing, SIP and ICF. ICF was over twice the price of 2x6 or SIP. I decided upon SIP and am currently building. I would love to live a concrete house but at $100K for exterior walls vs $40K for SIP it did not make sense.

 

[JB4310]

I think the concept is great, they just have not caught on, and that's been the case now for 30 years, 20 years ago they had not caught on. 10 years ago they had not caught on. So it looks like they never will.

It's got to be the cost or else we would see more of them. If it was only 5-10 % and the house would look the same, people would be building them just for the energy saving factor.

No reason a wood framed house can't be passed on for generations, My first house was built in 1832 !!

JB

 

[Mounted Madness]

We had our house built in 2007, moving in Jan 2008. We'd looked very seriously at ICF for the whole build, rather then the standard concrete foundation and stud walls. With the increasing frequency of high winds and even tornados, I figured concrete would be the way to go.

The lot we wanted was owned by the builder, so it was that builders price quote that we had to follow. Their standard build was the usual concrete, studded and insulated, with standard frame construction above grade. Our last house had ICF foundation, so we had the builder quote that...$8,000 more for the foundation.

The basement is warmer and quieter and less prone to humidity we get here in the summer. Looking back 4 years ago, and if we'd had the extra $8,000 for the main floor, it would be an option I would go for without hesitation.:thumbsup:

The cost difference would have been about 6-7% more by my estimate from the standard build costs.

 

[rgood]

I just googled "Cost of ICF house" Every one that comes up says 2 to 10% more except for one that said 20% more.

Maybe there are some "regional cost differences?"

I think alot of the difference is in the Labor costs.

The builder I'm working with only builds ICF houses - I think that makes a difference too.

 

[czechsonofagun]

If the market was geared towards brick, stone, concrete building, the cost would drop too.

In my country it is the same as Germany, buildings from wood are just temporary or summer cabins and such. And we don't have the America's crazy weather like tornadoes - strong winds may damage the roof and break windows but they will not make a pile of rubble from a house. Also thing to consider is fire - wood house means you are living in a pile of kindlings - if you ever saw stick build house burn, you know what I mean.

 

[JB4310]

I just googled "Cost of ICF house" Every one that comes up says 2 to 10% more except for one that said 20% more.

Maybe there are some "regional cost differences?"

I think alot of the difference is in the Labor costs.

The builder I'm working with only builds ICF houses - I think that makes a difference too.

I don't get it, if it's even 10% higher that would not be enough to turn away people who are building their dream home, especially if it is a better type of construction (which I believe it is).

Sure a profit builder is not interested in paying more for anything, but an American consumer.....

Are these numbers just for the cost of materials? cause everyone working on the house, from plumbers and electricians are going to face things they are not use to, which is going to cost more.

I've seen ICFs at trade shows 25 years ago, never seen a house built with them though. I would like to build a shop with them some day.

I don't even see the need for the insulation, those forms are the expensive part, why not just conventional forming and a styro board put over the out side wall.

Isn't 8-10 inches of concrete a pretty good insulator? Maybe not since there is not alot of air space in there?

JB.

 

[dmccarty]

An ICF house costs more for very little benefit when we built. At that time concrete was very expensive, was in short supply, and was being rationed to builders. Using concrete for ICFs would have been very expensive. I think we paid $90ish per yard and that was cheap. Other places were charging $100-110 per yard. The concrete cost for ICF in our house would have been around $4,000. Then you have the cost of the ICFs, rebar, and labor.

I seriously started looking at ICF's back at least in the early 90s. Contractors are very conservative in what they do and for very good reasons. Not many build with ICFs so you either have to find a builder with experience or deal with an inexperienced builder. Which is going to increase your costs and risks.

From an energy efficient perspective a stick built house can easily meet or exceed an ICF house. Just not that hard to do for less money.

An ICF house could/should be better in a tornado but the odds of a tornado hitting my house is basically zero. I looked at tornado data for my state and I think my county has only had 1-2 tornado very few decades. The chance of my house getting hit is pretty small.

Another item we wanted in the house was a fire sprinkler system. The old code made it all but impossible to put in a fire suppression system however the code changed just before we built. I asked the insurance company how much my house insurance premium would decrease if we had a fire sprinkler system in the house. It was something like $25-50. A year. This told me that the odds of my house burning down was also close to zero.

For hurricanes, the ICF house has an advantage if the windows and doors can be protected from debris. If the windows and doors fail, and the wind gets into the house, I am not sure how little hurricane clips are going to hold down the roof in big wind. Our house is well inland but hurricanes can and have had hit our area. We have hurricane clips. I think our house would survive window/door failure because the winds would barely be hurricane strength. Down on the coast would be a far different story.

Our house has R25 2x6 walls and is very quiet. It would be even quieter and more energy efficient if we had not put in lots of big windows. The windows was also a reason to not use ICFs. Why build this expensive exterior wall and then poke holes in it?

We found a builder we liked, was a PE, knew his stuff, could be trusted and who became our friend. How many people can make that statement about their builder? He was very willing to build with ICF but it would be a learning experience for him and a risk for me. Simply not worth the risk for little to no gain that I could see.

When it came time to spend money I just could not justify the extra cost, and in our case, risk, to use ICFs.

If I lived in a place where very strong hurricane winds could hit, I would seriously think about ICFs.

Later,
Dan

 

[EddieWalker]

HGTV had a show called Dream House where a guy built his house from concrete. Before they started, he researched all the ways to build and what would be the most energy efficient, strongets and cost effective. He went with concrete. What made the show so interesting was all the problems they had in building it, and then turning that frame into a house. It was basically one disaster after another, every little thing that had to be changed, or added because a huge deal.

Just like Log Homes, they tell you that the mass creates a thermal barrier and it holds it's own energy. It sounds great in theory, but in reality, it's just not there. The foam on inside and ouside of the concrete is where you get your insulation. Once you have it built, will you have to stick frame the interior walls anyway? Will you remove the foam and use the concrete as the interior wall?

Have you read through Sam Walton's thread on his concrete house? It's an amazing project, but his cost for square foot isn't even close to what you could do it for stick built.

Just my opinion, but I think that it's going to cost twice as much to build a house with ICF's to the finished, livable, all done home that you will live in then it would using standard lumber and building to code.

The new Florida Code for Hurricanes is very impressive. From what I've read, they have really improved it. Same with CA and LA. Not all homes are built the same, and in some parts of the country, there is some real engineering that goes into these new construction houses!!!!

I'm not against building with concrete, and think it's a great method for a variety of reasons. What I'm against is the added cost that I feel makes it cost prohibitive for anybody with a budget. I also don't have any experince with it. I work with wood, and have a good idea what that costs. Before doing anything, I would talk to at least ten people with ICF homes who built them theirselves or with contractors, but are the original owners to find out what they say about the cost of building it was. Not just the frame, but to completely finish it and to be able to live in it.

Eddie

 

[rgood]

. The foam on inside and ouside of the concrete is where you get your insulation. Once you have it built, will you have to stick frame the interior walls anyway? Will you remove the foam and use the concrete as the interior wall?

Eddie

No, you don't have to build a stick wall inside of the house, the drywall is screwed to the ICF blocks at certain places.

You don't remove the foam as that is your insulation - The electric is placed in the foam by using a router to make a groove - It's easier to router foam then it is to drill holes in wood.

 

[EddieWalker]

No, you don't have to build a stick wall inside of the house, the drywall is screwed to the ICF blocks at certain places.

You don't remove the foam as that is your insulation - The electric is placed in the foam by using a router to make a groove - It's easier to router foam then it is to drill holes in wood.

Thanks. I remember reading that now that you've reminded me of how it's done.

Eddie

 

[fish6942]

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.

 

[beppington]

I don't get it, if it's even 10% higher that would not be enough to turn away people who are building their dream home ...

The monthly payment on a $250K home with 20% down & a 5% APR, 30 years = $1,073.64

10% more for ICF: The monthly payment on a $275K home with 20% down & a 5% APR 30 years = $1,207.85 ... $134.21/ month more. A total of $48,313.95 more over the life of the loan.

Seems most people buy the most home they can afford ... so will they be willing to reduce the size, features, etc. in the home in order to opt for ICF?

 

[beppington]

The new Florida Code for Hurricanes is very impressive. From what I've read, they have really improved it. Same with CA and LA. Not all homes are built the same, and in some parts of the country, there is some real engineering that goes into these new construction houses!!!!

This is a fact! Dad & I built a sunroom addition to my sister's house in '08, & even being a big room full of big windows, I'd take my chances in there during a hurricane over any place in my entire 1992 home.

 

[dmccarty]

The monthly payment on a $250K home with 20% down & a 5% APR, 30 years = $1,073.64

10% more for ICF: The monthly payment on a $275K home with 20% down & a 5% APR 30 years = $1,207.85 ... $134.21/ month more. A total of $48,313.95 more over the life of the loan.

Seems most people buy the most home they can afford ... so will they be willing to reduce the size, features, etc. in the home in order to opt for ICF?

Bing Bing. You can buy ALOT of very expensive energy for $134 per month. $134 is more than my average monthly power bill.

We wanted to put in active solar water and house heating in the house. Best estimate was about $9K on top of the HVAC. No way could I justify the extra cost of something to supplement the HVAC heating and wood stove. The wood stove is more than enough until we have those few days a year were the temps drop into the single digits or teens. We could buy a second wood stove for much less.

Later,
Dan

 

[scgargoyle]

I'm considering ICF, at least for the basement. If I do it myself, the cost is about the same as hiring someone to pour a basement. DIY, you can build ICF for about $6 square foot, depending upon local concrete costs. You can buy SIP's for $4/$6 a square foot, although they obviously wouldn't work for a basement. I can stick frame, with external foam insulation and blown-in cellulose for a little under $3. All of these numbers are square feet of wall area, not floor plan space. From the least expensive to the most is $3 square foot, or about $6000 in the case of my small house. Really not much money in the grand scheme of things. Bear in mind- that's DIY. I had a builder quote our modest 1300 sq ft design, and they wanted $95,000 for just the shell. That includes roofing, windows, siding, and doors.

What do I like about ICF? Strength, airtightness, quiet, doesn't burn, rot, or get eaten by termites. I think it's a good system to DIY, provided you have some skills, and can get an experienced person on site before you pour. One person can stack and brace the walls pretty quickly, working alone. SIP's would go up pretty fast, too, but would be harder to do solo.

What do I NOT like about ICF? Expensive (if hired out), termites are known to tunnel undetected through the foam, and it's very difficult to make changes to the house down the road. Want to add a window? We're talking heavily reinforced concrete- ouch!

I'm building in SC, which is rated 'Extreme' for termites. If I can convince myself that termites can in fact be controlled, I'll go ICF on the basement. My contractor only builds ICF, and he will run the pour (for a fee) if I want to stack my own blocks. If money were no object, I'd go ICF to the eaves, with metal SIP's and framing for the roof.

 

[BobRip]

I had a 3500 sq ft ICF house built in 1994, and I still live there. I got a quote for 2x6 construction and it was about $2000 less than ICF. Concrete cost depend a lot on local availability of raw materials. You don't want to transport sand and gravel long distances. Let me summarize below

1. Average heating and cooling cost per month for the first 5 years was $30.

2. We could hardly hear hurricane Isabel when it passed through. We don't hear thunderstorms, ie they don't wake us up.

3. I did the wiring and it was not difficult to cut channels with a hot iron (electric charcoal lighter).

4. Don't get the first house built by a builder. Mine was the third. There is a learning curve.

5. The local power company did a blower door test and we were twice as tight as the next best house ever tested by the test person. His house was the second best and he did everything he thought possible to seal it.

6. Be sure to put in an air to air heat exchanger. Odors can build up.

7. Humidity is the biggest cooling load. Do not oversize your AC.

 

[westcliffe01]

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.