GreenBuild: Durisol, the Green Insulated Concrete Form
by Lloyd Alter, Toronto 
on 11.26.08
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.
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.
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. Durisol Insulated Concrete Forms
More on Insulated Concrete Forms in TreeHugger
Insulated Concrete Forms: Another Opinion
What Lies Beneath: Our Homes' Foundations
Follow @TreeHugger on Twitter & get our headlines with @TH_rss!
Thirsty for more? Check out these related articles:
- Surf Green with Eco-Friendly Surf Gear
- Build a Greenhouse without Going Broke
- Are You Harboring These Dangerous Products?
- Recycled Plastic Workout Gear is Great for Fitness, Great for Planet
- Mini Blinds are Boring—Craft Them into Chic Fabric Shades
- Green Glossary: Ingeo
I am not a huge fan of the foam ICF because of the thermal mass being isolated from the inside and the petroleum based foams, but in Durisol you do have those "wood chips and a bit of portland cement" acting as a thermal bridge from exterior to interior and you have discontinuous insulation not unlike a stud wall.
What is the Durisol insulation made of?
What is the R-value?
Also wouldn't a bio-based block be more susceptible to all kinds of moisture, mold, rot and insect problems?
what about earthquakes - is this stuff as good as traditional reinforced concrete?
Interesting looking stuff. I didn't consider using it because when I researched on ICFs 4 years ago, I didn't see these. I ended up using QuadLock for the foundation of the addition I built.
According to the Durisol web site, the wood is 'mineralized', making it inert and "no longer susceptible to rot or termite damage." Depending on the thickness, they're between R-14 and R-28.
someone should get that bottled water out of that guy's hand and get him some nice refreshing water from the tap!
I am in south florida. are there any installations here? Is there a distributor in my area? thanks, Jeff.
This has to be one of the most unique things I have read about in a very long time. I love that idea and the design.
I have used the Durisol product before. We have found it much easier to work with than styrofoam, it can be screwed at any point and it is much stronger also . The fact that it is a " Green Product" , we also found that very appealing.
James
Hi:
I am a Durisol representative and can answer some of the questions posted:
1. Durisol material itself has an R-value of 1.75 per inch and therefore the R-value through the web of our standard 12" R-21 block is actually R-22 while through the cavity it is R-21. This means there is no thermal bridge through the web and the insulation is in fact contiuous
2. The insulation insert is rockwool with an insulation value of R-4.3 per inch.
3. Durisol is completely durable and not susceptible to moisture. Since the wood is mineralized and encased in cement there are no potential issues with rot, termites, etc. We have completed a 7 year termite study with the US forest service that shows no susceptiblity to termites (unlike styrofoam). Also, our products include noise barriers along highways that are exposed to all seasons, moisture, salt, freexe-thaw etc and have been in place for over 20 years on North American roads and still performing perfectly.
4. The design of the Durisiol system is actually better for seismic response. In the event of an earthquake, as the wall deforms, the smaller horizontal cores will yield and the structural assembly transforms from an integrated screed grid concrete wall to a series of vertical concrete columns. This allows the walls to become more ductile and disipate more of the seismic energy. This is a well documented behaviour of this type of system.
If you are worrried about bridging (which may or may not be a problem) a moisture barrier of blue board on the outside would mitigate much of that.
what are the behavioral characteristics of durisol bricks when pulverized by various martial arts strikes and chi harnessing techniques? are they comparable to cinder blocks? this is particularly important for those of us shattering the blocks with forehead strikes.
For plumbing/electrical I'm assuming one would need to still frame the inside with conventional 2x4's? or is there some conduit system internal?
I am a rep for Durisol on the west coast,we currently have a passive solar home under construction near Yosemite if anyone wants to see one,and pictures are posted on my website.