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Legos for Homes: Foam Blocks and Poured Concrete

Found the following exchange while searching for info on alternative housing construction:

Q: I am currently designing an earth-sheltered home, but have been unable to determine the best building material for my location and how this will affect my design. I have been leaning toward lightweight concrete lately as I am impressed with the creative flexibility of it. I live in an extreme climate (Northern Canada)temperatures range anywhere from -40 to 104F, the prairies are dry and windy. I will be covering all but the south side of the home with earth, as this is where my greenhouse will be going. I would like to build it right into the house rather than externally and am expecting high humidity inside there, I will be separating the greenhouse from the main house with glass. I was hoping you could recommend the best material for me to work with, or if you know of any reference materials dealing specifically with this climate.

A: (J.M.) I would suggest using foam blocks and poured concrete. This method is very easy to use. The foam blocks are shipped flat and put together with plastic spacers. The walls go up quickly and are tied together with string. Additional wood braces are added, and then the walls are filled with concrete. Make sure you fill the wall in layers to help prevent a blowout. (Filling the walls in layers of a couple feet or so at a time allows the concrete to setup and reduces the likelihood of a blowout.) I've seen this technique used a couple of time, always with great success. If it's available in your area, I would suggest you explore using this method.


Here's what I found on yet another website:

One of the best house construction methods, considering your particular concerns about disasters, is stay-in-place-form concrete walls. These houses are not only super energy efficient, but they are extremely strong. Even tornado or hurricane winds won't blow one down.

Other than deeper window openings, these homes look like any other. Your architect will actually have more styling flexibility due to the strength. Interior and exterior walls can be finished with drywall, paneling, siding, brick or stucco.

I would recommend one of the foam block building methods. These are large, often four-foot-long, hollow foam blocks. They are usually made of polystyrene insulating foam like a cooler. Once the blocks are stacked up to create the wall, concrete is pumped in the top to fill the hollow block cavities.

You can expect your utility bills to be about half those of a code stick-built house. This results from the high insulation level and the efficiency benefits of the high thermal mass of the concrete. The overall building cost is only about three to five percent more than a lumber stick-built house.

The first thing you notice when you enter one of these houses is how quiet it is. The heavy insulation and concrete mass inside the walls block outdoor noise. With the concrete core and tight sealing foam blocks, the homes are very airtight. This is an advantage for your terrorism concerns.

You have several choices of foam block designs. One type, called waffle, uses molded all-foam blocks with internal webs. This creates continuous cavities of various widths. If you would break away the foam insulation after the concrete sets, the concrete surface would resemble a waffle.

Another effective design is a flat wall. These blocks are made of flat sheets of foam insulation, usually about two inches thick. There are metal or plastic webs in between them to space them apart. When the concrete is poured in, it forms a core of constant thickness, often six to 12 inches.

The waffle-type blocks produce a higher overall insulation level because there is more foam. Also, less concrete volume is needed to fill the wall. Talk to builders to see which they prefer to use in your area. A third foam block design produces a post-and-beam concrete pattern inside the blocks.

There are also new foam floor/ceiling/roof insulating foam forms. Concrete is poured over them and in channels. They are very strong, efficient and quiet.



Here's a link for more information about foam blocks (also known as Insulating Concrete Forms or ICFs): http://www.consumerenergycenter.org/home/construction/forms.html - talks about R-values (insulation quality), earthquake reinforcements, insect resistance, and more.


There HAS to be a lot of suppliers out there for foam blocks to be used with poured concrete, but I'm having troubles finding them!

Checked out the website for Home Depot - nothing turned up for my search. Called their customer service department, and the twit I talked to didn't have a clue as to what I was talking about. Said to check in the store ... when I said it wasn't for me and was probably across the country ... she got kinda smart aleck. So... dead end.

Called Lowe's because couldn't find anything on their website either. At least this customer service rep was nicer and said he would try to find someone at my local store who knew more about it. They checked, called me back, and said their stores don't have anything like this.

Does anyone know suppliers for these ICFs? If so, please feel free to leave the info here as a comment. Thanks!

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