Fire

How well do ICF walls hold up in fire?

The graph above shows a comparison of the performance of ICF walls and wood frame walls during laboratory conducted "fire-wall" tests. In these tests, ICF walls were subjected to continuous gas flames and temperatures of up to 2000°F for as long as 4 hours. None of the ICF walls ever failed structurally. All of the ICF's tested were of the "flat" or "uninterrupted grid" type, having no significant breaks in the concrete layer. In contrast, wood frame walls typically collapse in an hour or less.

Do they stop fire from spreading?

Concrete walls have also proven more resistant to allowing fire to pass from one side of the wall to the other. This is especially of interest in areas with brush fires that could spread indoors.

The fire wall test confirms this rule for ICF's once again. Part of the test measured how well the wall slows the passage of the heat and fire from the side with the flame to the other side. The ICF walls tested did not allow flames to pass directly through. They also did not allow enough heat through to start a fire on the cool side for 2-4 hours. In contrast, wood frame walls typically allow both flame and fire-starting heat through in an hour or less.

Will the foam add fuel to the fire?

The foam in ICF's are manufactured with flame retardant additives. These prevent the foams from burning by themselves. If you hold a match to the material, it will melt away. However, when the flame source is removed, the flame extinguishes.

Can the foam give off harmful emissions?

Practically any organic material, be it wood or plastic, gives off emissions when it is subjected to intense heat or flame. The Southwest Research Institute reviewed the numerous existing studies of fire emissions and concluded that emissions from polystyrene foam are "no more toxic" than those from wood.

What precautions should I take to make my house fire resistant?

No matter what your walls are made of, there is no sense playing with fire. Building codes require covering the inside face of exterior walls with a fire-resistant material, such as gypsum wallboard or a stout plaster.

In areas prone to outdoor fires, it is wise to finish the exterior with a fire-resistant material, too. Favorites are Portland cement stucco and masonry.

And of course the more you can design your home to limit the exposure of flammable materials like wood and fabrics, the better.