Insulated Concrete Forms for home building?

Randy Rooster · #1 10/22/05, 02:35 PM

I am wondering if any one here has built a house or building from concrete using ICforms? I am looking into it for my new house, and aside from the slightly higher initioal cost, I have not seen any bad things said about it or heard of any drawbacks.

painterswife · #2 10/22/05, 03:55 PM

You get more R-value for less money using structural insulated panels.

While ICF's are great they are less cost effective.

Jill

cricket · #3 10/22/05, 04:03 PM

You also don't get the utility savings they talk about either if you are where it gets hot. I'm not sure about savings where it's cold. Also, if you have never worked with them before you really do need someone familiar with this type of building to oversee the outside walls. Concrete is concrete no matter where you put it and you can end up with some real problems. (We work concrete for a living.) Otherwise, they are pretty good houses. They have pretty hhigh wind ratings etc.

JAK · #4 10/22/05, 04:09 PM

I would say the same. They look great. So far they seem to work great. I have seen some nice homes go up in our area using them. I have also seen upper stories use them for nice thick walls and heat mass. But they are expensive. Even conventional concrete with rigid foam on the outside would appear to be cheaper, and a better use of heat mass.

Still, the best style and materials to build a house are inter-related, and depend on a lot of local factors, and personal ones also, of course. I've always been partial to the idea of thick whitewashed, but otherwise uncovered concrete walls with rigid insulation on the outside, and parging on the ouside of that, with a combination of passive solar heat, active solar hot water, and wood heat and hot water. All in a small storey and a half house without a basement, with insulation under the slab or cobblestones. The idea is to recreate or resemble a Scottish or Irish Cottage, but without the creeping damp, and perhaps without the cattle in the adjacent room.

Notwithstanding the issues of concrete mentioned above, it can be a very beautiful material for walls and floors and baths and sinks and things. Pretty permanent stuff though, which can mean permament problems if you try to cut corners and hire the wrong crew.

ET1 SS · #5 10/22/05, 07:43 PM

I have seen them, they look cool.

But I am jsut finishing our new house made from a steel building. Much cheaper than a stick-building, per square-foot.

:baby04:

SolarGary · #6 10/22/05, 07:54 PM

Hi,

There is a fairly detailed description from a person who built a house using ICFs for the foundation and SIPs for the main floor here:

http://www.builditsolar.com/Projects...s/ididitps.htm

Look for the "One Year in a Foam Home" story.

Gary

jeffreyc256 · #7 10/23/05, 01:14 AM

I am looking at a similiar alternative. It is Dow structural Insulated panel, kind of the reverse of what you are lookin at. It is basically a concrete sandwich with insulation in the middle spaced by nonconductive carbon fiber spacers. It can be poured on deck like a standard tilt up system or poured in place. I think it will be very efficient and you can incorporate form liners from symons or fitzgerald forms to texture one or both sides and use color additive and eliminate any other wall treatments.

I would suggest a site I found for other good design ideas www.ourcoolhouse.com

Randy Rooster · #8 10/23/05, 12:04 PM

cricket said - You also don't get the utility savings they talk about either if you are where it gets hot.

Can you clarify this for me? Why not? If the r value is 50 which they claim, then would not the electric bill for a/c be less than a poorer insulated house?

Randy Rooster · #9 10/23/05, 12:13 PM

I just read that link on the sip foam panels. I dont think I would go for that method in a million years even if I didnt live in a hurricane prone area.

cricket · #10 10/23/05, 12:42 PM

Around here there was a lot of hype about how you wouldn't have to use the a/c as much as they stay cooler in hot weather. Whoever made that statement didn't take into account the humidity factor - and that's a huge issue here in the south. As a result, you still run the a/c as much as any other type of construction. R-factor really only deals with cold issues. Of course, if you live in the south and have the humidity issues, or even where it's just plain hot, the style of construction has A LOT to do with energy savings. Unfortunately builders claim "southern building" and they are simply transplanted designs from the north and west... You discover what kind of hinderances you have with those styles when the power goes out and it's 100 degrees in the shade with over 100% humidity. Miserable. But boy, when it's the 2 weeks of really cold weather you have a GREAT house.

With ICF, regardless of which forms you use (and they are all about the same in the end) you must know what you are doing with concrete especially if you live where it freezes. There are people that will tell you the forms create expansion joints...not true. I've seen whole walls shatter because the person who poured it assumed it was true. Also, you have to get the mud in without air holes and still use fairly dry mud...somewhere around a 4 slump or less. Anything over that and you are comprimising the PSI value of the concrete and I don't know about you, but if I'm going to be sitting/living on the other side of that wall I don't want any compromise. Concrete acts like a sponge and will expand and contract with the seasons and the humidity. If they aren't built correctly, you can have disatrous results.

Randy Rooster · #11 10/26/05, 08:01 AM

hmmm- thanks Cricket
those are certainly some things to ponder. How did you come by your concrete experience and is there any thing else I ought to be aware of?

gobug · #12 10/26/05, 11:44 AM

I helped a friend with his house, but he had a crew from the mfg put up the walls and fill with cement. Even with the experienced workers, there were a few spots where the cement busted out of the forms and had to be re-done. When finished, the house was noticably more quiet than regular houses.

Another factor not often considered is that carpenter ants and termites can be an issue. They do not eat it, but will go through without delay. Carpenter ants can nest in it. When the foam is gone, so is some of the structural integrity. Some mfg's add a pinch of boric acid to the foam to prevent this problem.

As mentioned above, the high value is not accurate in the humid southern climates.

Another product you might consider is a new variation of autoclaved aerated concrete (AAC) which has been used in Europe for more than 50 years. It's always been too costly here, but, a new process has been developed. The product is called Flexcrete. It comes in 8x8x24 blocks weighing 30 pounds each and has a high relative r value. It also comes in 8x12x24 and reputedly has a relative r value of 30. The smaller blocks only cost about $3. They also make roofing and floor panels.

Here's the website if you're interested:
http://flex-crete.com/index.asp

frazzlehead · #13 10/26/05, 01:45 PM

We did the foundation for the crawl space with them, and they were easy to use. For us, the key was that it could be done quickly and with not too many bodies - we are on a time crunch trying to beat old man winter! Mom and Dad and the construction guy built the foundation lego structure with the foam blocks over a day and a half, and the second half of that second day the concrete truck came and poured. Mom covered the outside with tar (that took a day) to waterproof, and voila, we were done. 3 days to a complete foundation (well, then 2 more to get gravel in the bottom and put the cement floor in).

No info on making a whole house with it, but there's what I do know.