My family and I had a small (F1) tornado pass almost on top of our house during the wee hours of Friday night. There were a lot of trees down and my neighbors had broken windows but no one was hurt. That was my second tornado experience. The first one was a little stronger but may also have been an F1. I can’t imagine living through an F5. I love framing a house with traditional lumber but it sure would be nice to have a concrete house. It seems like the weather is getting increasingly unstable these days.
Does anyone here have any experience with insulated concrete forms? I’ve done some research and of all the brands I’ve seen, Quad-Lock seems to be my favorite. I’ve heard that some ICFs can have mold problems. Moisture from the drying concrete collects between the concrete and the insulation and breeds mold. Is this true? It seems like the moisture could escape through the breaks in the insulation.
If anyone has worked with ICFs , I’d sure like to hear about your experiences. I’m a GC but have no experience with ICFs. Thanks for your help.
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i have worked with the Arxx sytem for about 4 years and and am now building my first custum home . we already pored the walls and it went great. i used the form which holds 4" concrete, we usually use the 6". we saved abit on steel, concrete, and living space by using the smaller block.you may also want to check out Reward Wall brand i really like their block. I like arxx because the "rib" is exposed and it makes it easier to run siding. i have quite a bit of knowledge about icf @ my young age of 24 and would love to talk more
RTC TEKTON CONST. CORPUS CHRISTI,TX
Do a search here at BT for "ICF". Lots of past discussions.
Ditto on searching past discussions.
As to standing up to high wind loads, keep in mind that many of the "basic" ICF walls specified for residential construction aren't necessarily designed for what you are looking for. Often just the outer shell is ICF with interior walls being framed conventionally and simply butted to the interior foam. So basically there are not interior sheerwalls, unless designed that way, which is often overlooked. Despite what many will claim, long ICF walls won't stand up to high winds without damaging movement, and the engineers from any of the manufactures will confirm this.
I'm also a fan of ARXX and have a copy of their "Prescriptive Design Requirements" floating around the bookshelves and it was surprising how limited an ICF wall can be. In south east Wyoming, where measured gusts of over 100 mph aren't unheard of in the more windy areas, we had to watch our wall lengths/heights as per the specs., although they probably are a bit conservative just to meet a number of building codes with one document.
As for the mold, it could very well happen. If a moisture barrier isn't used around the footer, the concrete "channels" within the block will transport moisture up the wall, since there is little moisture that can escape through the foam before it reaches the top except for the various small gaps, which may be the source of some small areas of mold.
If a moisture barrier on the footer is used, the moisture within the concrete will work it's way out, mostly out the top and the wall will completely dry out.
My guess is that an ICF house with larger scale moisture/mold problems is do more to the shell being tight, combined with inadequate ventilation. ICF houses do very well with blower door tests, especially if a thin layer of foam is sprayed in the attic before insulating. We always included an air exchanger.
In the worst case senario, someone left out a moisture barrier under the floor slab or crawlspace so there is a huge amount of trapped moisture that needs to get ventilated out of the shell. This would cause mold in a tight shell of any type of construction.
My biggest ICF warning would be to have a robust plan for keeping the walls straight during a pour since it's very easy to underestimate how much a wall will move once mud has been pumped in. Remember bracing can push an ICF wall, but it can't pull and you're in better shape than most.
Cheers,
Don
http://www.allwallsystem.com/
This system seems a very good alternative.
Very good website.
I just built using Amvic forms - they are probably about the same as any. I was happy with them, and my choice was based upon price. Phoenix seems to be the price leader now, however, and I'd go with them if I did another.
Do a google search on HUD's Prescriptive Manual for ICFs. It is available as a free PDF download somewhere.
Other ICF forums exist online - there is a lot of good and bad info out there.
One tip I never saw - use a trailer pump, not a boom pump - much, much easier to control.
They are not bad to work with - I had 2 high school aged helpers and they were on task by the end of day 1.
I think we are going to love the house...