GreenBuild: Durisol, the Green Insulated Concrete Form

materials monday polystyrene image icf

There was an entire row of exhibitors showing various incarnations of insulated concrete forms (ICFs) with their styrofoam walls and their plastic ties that are filled with concrete and then labelled green. Then there is Durisol, that has been around for half a century. it is made of wood chips and a bit of portland cement, 78% recycled materials, is noncombustible and is the original insulated concrete form. So why is it always ignored?


exposed Durisol at Fifth Town Cheese
Perhaps it suffers from a "not invented here" factor, being developed in Holland and Hamilton, Ontario. Perhaps it is because it is proprietary rather than foam ICFs, where there are a dozen different systems. A case can be made that it is a lot greener and a lot better:

Durisol does not burn or melt. This is not the case with styrofoam and other ICF products. The smallest Durisol wall has a 4 hour fire rating, zero flame spread, smoke spread of 11 and no black smoke or toxic fumes created in the event of a fire.
Durisol is more energy efficient. The thermal mass/dynamic effects are better with Durisol than other ICF systems because with Durisol, the insulation is placed primarily on the exterior of the concrete mass. Polystyrene ICF foam blocks put 50% of the total insulation on the interior, which actually prevents the transfer of heat/energy between the concrete mass and the interior conditioned space. With Durisol, all insulation inserts are positioned towards the exterior, where it should be, to maximize any thermal mass gains.
The composition of Durisol is all natural and benign materials - unlike polystyrenes.
durisol healthy wall

It is easier to use and avoids the problem of voids:

Durisol Wall Forms are much stronger, and can withstand higher concrete pressures. We have zero blow-outs in the field when poured in accordance with our recommendations.
The blocks require less bracing than the foam ICFs and Durisol walls don't bow and bend as easily as the foam blocks. Also, since the blocks are uniform, it is possible to drywall or attach screws to any point on the finished surface, not just at the discrete plastic web locations that are difficult to find with tradtional ICF materials.
Because the Durisol is a free draining material, it is possible to use a high-slump concrete (7" — 9" slump) without adversely affecting your concrete strength. When pouring a very wet concrete mix, the Durisol material immediately starts to drain the moisture so that it does not result in weaker concrete, while ensuring that there are no voids and making the pouring process easy.
fifth-town exterior photo

The Fifth Town Cheese Factory was built out of Durisol for LEED points.

It is just one of those products that is so logical, yet has just never found its place. I wish I knew why.