Sunday, May 22, 2011

Why ICF (Insulated Concrete Forms)

The vast majority of US and Canadian houses are wood-framed using 2x4, 2x6 or 2x8 framing to build the above-ground exterior walls and cinder or cement blocks for the basements. This is not the most efficient method of building since you are not creating a truly solid wall but are 'constructing' a wall made out of separate pieces. Insulating Concrete Forms (or ICFs) create a structural concrete wall (either monolithic or post and beam) that is up to 10 times stronger than wood framed structures. There are plenty of other benefits (see the Wiki link on the title for an extended list) but the two that sold us were the aforementioned rigidity and the far better insulation value of the wall over the wood-framing.

It's constructed a lot like hollow lego-blocks that are dry-stacked together to form the wall frame. Rebar is added for additional horizontal and vertical strength and then back-filled with concrete inside the frames. As opposed to regular concrete walls, the blocks are NOT removed and will enhance both the thermal and noise insulation value of the wall.

Since it is concrete it is vitally important that you know before construction where you want windows and doors placed since cutting through 6 inches of solid concrete and rebar to add a window is a real pain (and not to mention, expensive). Talking about expensive, ICF construction will add a few dollars to your square foot price (usually between $1 and $4) but that will easily be recuperated through lower energy bills and a more silent, clean and rigid house.

If you are not convinced about the concrete, but do understand the energy-inefficiency of wood framed houses, other construction options are available such as SIPS panels, earthen walls or other more 'green' options.

Overall, the benefits of ICF outweigh the negatives for us and with Charis Homes specializing in ICF construction we went for it.

Update 5/24/2011: With all the tornadoes we had in the States these last couple of days - and some confirmed TDs even here in North-East Ohio - we are very glad to be building with ICFs. We've seen many a picture of where ICF houses were the only ones standing with all surrounding houses gone. That is one of the reasons why ICF is one of the few FEMA-rated construction methods... It also saves you on your home owners insurance as well (we already have proof of that...!) Consider this: a log hitting an ICF wall at close to 100mph will still simply shatter on that wall where it would simply go through a wood framed wall.

Note: for those interested, our ICF house will use ARXX Edge blocks (formerly known as ECO-Blocks)

Update 6/22/2011: More reasons in the follow-up post
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