Why Build an ICF House

[zmjc]

Around here, I think the odds of a bad earthquake are much higher than the odds of tornadoes or mass fires.

I wouldn't want to be in a concrete house in an earthquake, personally. I'd rather have 2x4s and drywall falling on me.

Just something to consider...

 

[JB4310]

Around here, I think the odds of a bad earthquake are much higher than the odds of tornadoes or mass fires.

I wouldn't want to be in a concrete house in an earthquake, personally. I'd rather have 2x4s and drywall falling on me.

Just something to consider...

Makes me wonder, which would be better steel reinforced concrete or stick built. I think both would hold up to an earthquake pretty good. But I think I'd take my chances with the concrete, if it were properly reinforced, the walls could not buckle outward like a stick built might, allowing the roof and floors to come down inside.

Where I would not want to be in an earthquake would be a conventionally built masonry structure, especially the older ones built in our cities. The 3-5 storey 80 to 100 year old brick buildings with no steel. they are basically held together by the weight of compression of the brick, the mortar is just firm sand now.

We are past due here in the North East for a serious earth quake, if it ever does happen, it's gonna be ugly.

JB

 

[Larry Caldwell]

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.

No, concrete is not particularly a good insulator. You are right about the concrete walls, though. Incorporating all that mass inside the the thermal envelope really stabilizes the interior temperature. I have built houses with concrete walls, styrofoam exterior insulation, and stucco siding over the styrofoam.

The cheapest way to build concrete walls is tilt-up. After pouring the slab, you cover it with plastic/plywood/release agent and form wall panels, box out window and door openings, tie in rebar with pick points (available commercially) and trowel it smooth. After it cures for 2-3 weeks, call a crane and stand it up. After you have the walls braced in position, you can either pour concrete pilasters at the joints to hold the building together, or you can cast steel Nelson studs into the corners and weld the joints together.

Alternatively, you can build concrete block walls. Pumice block is lighter and easier to build with, but doesn't have the thermal mass of heavyweight block. If you fill the cells of heavyweight block with concrete instead of just casting 4' x 4' bond beams, it will be almost as heavy as a cast concrete wall.

Setting up forms and casting concrete walls in place might be an option if your contractor does basements, which means he would have the crew and the forms.

The big down side of concrete walls is remodelling. When I replaced the windows in my 40-year-old stick framed house, I swapped the 2 x 2 kitchen sink window for a 6' bay window. That would have been a really expensive project in a concrete house.

 

[Larry Caldwell]

Makes me wonder, which would be better steel reinforced concrete or stick built. I think both would hold up to an earthquake pretty good. But I think I'd take my chances with the concrete, if it were properly reinforced, the walls could not buckle outward like a stick built might, allowing the roof and floors to come down inside.

Light weight wood structures fare much better in earthquakes than heavy concrete structures. They move easier. Nothing stands still in an earthquake.

It takes a lot of engineering and rebar to make a concrete structure earthquake resistant, while there is a prescriptive path for wood structures. Build the shear panels and use the connectors specified in the IBC, and you are good to go.

 

[scgargoyle]

The place I work at is built out of tilt-up concrete walls- about 30' tall! It's pretty solid, and could probably handle a decent hurricane, but a big earthquake would probably bring it down. Some of the most earthquake-proof buildings are either built on bearings to allow the earth to move under the building, or elastic shock absorbers to try to minimize the transfer of movement to a rigid building. Concrete has no tolerance for bending at all, so after an earthquake, the building would probably have to be torn down anyway, due to all of the cracked concrete.

It's hard to predict how safe various structures are- concrete can probably handle seismic forces better- right up to the point of failure. Then you've got tons of concrete collapsing on people. A wood frame structure might or might not fail sooner, but it will come down slower, and a person might stand a chance of not being completely crushed. Ya pays yer money, ya takes yer chances.

 

[rgood]

Well, here is my conclusion.

I had 3 different builders give me quotes on the house.

Only one gave me a quote in writing - And it was 3 times what a normal person pays for a house, maybe 4 times.

The other 2 guys did not put anything in writing, just gave me "ball parks" over the phone.

I'm sure all 3 of these guys can build a nice house, but their process of arriving at numbers definitely needs work. I'm not 100% sure that their inflated #'s were necessarily due to the ICF; I think it was mostly that they were not willing to do detailed homework analysis and they knew if they charged enough money, they were sure to come out ahead.

So, my conclusion is to go with a Larger company and buy a panelized 2x6 home. I have found 2 different companies that say they will guarantee the price and the move in date. They take my custom plans and build most of the house in a factory - Then assemble on-sight and add the wiring and plumbing. I will let you know how it goes next.

 

[BobRip]

The traditional way of building a house is like having a guy and his two brothers make the parts for and assemble a car in your driveway. The cost of that would be astronomical and the quality very low. Of course a house is kinda large to transport once assembled. Some kind of preassemble should help.

 

[grsthegreat]

Ive done wiring in a few ICF houses over the years, and one thing ill tell you is the cost for electrical work is alot more in these structures. Its a true bear to wire the exterior walls, that and the fact that the last few i wired had the ceiling joists and rafters attached to rim joisting left me with nearly an impossible house to wire. We are required to use a heat gun to cut a 2-1/2" deep path for the wires here in Idaho. The smell during this operation will knock out a goat.

The last one i wired about 2 weeks ago took nearly twice as long to complete as a standard house, and the price i charged reflected it.

I'm also verrrrrry leery about the possible fumes emitted from the Styrofoam walls for the life of the house. Dont care what people say, when your in that house you can smell it. The drywall hides it, but its still there. I personally would not want one.