A few weeks ago I sat down with the new owners of EcoInhabit, a wonderful green building business located in Meaford, ON. Tim and Jan Singbeil are passionate about green building and even more than just building energy efficient homes, they are passionate about building healthy, low energy-consuming homes.
At the core of a healthy home is the use of construction materials that are durable, mould and pest resistant and help with the overall air quality. In this case, the preferred building product for Jan and Tim is Durisol blocks. I was really curious about Durisol and I’d wanted to write about it for a few years, but my biggest hesitation was the fact that Durisol, like any insulated concrete form, depends on concrete for its full benefit, and concrete isn’t exactly the green builder’s best friend with all that energy intensiveness built right in. So I looked at Tim and said, “Convince me that Durisol blocks are a green building material.”
Our conversation lasted for over two fascinating hours, and by the time I left, not only was I a believer in Durisol, I was a believer in “healthy buildings” — which is about so much more than constructing energy efficient buildings — it’s about constructing buildings that take some of the toxic burden off our already too chemically-laden bodies.
If you’re not familiar with Durisol Blocks, they are in the family of Insulated Concrete Forms (ICFs), however, ironically, ICF manufacturers don’t consider them a direct competitor — and truth be told, they’re not, because they do so much more than provide a sturdy, well-insulated building. An ICF built foundation has many advantages over a simple poured concrete or block concrete foundation. An ICF consists of a brick-like concrete block, typically made out of styrofoam, and filled with concrete. The advantage of this building system is that it’s easy to assemble, it’s extremely sturdy, it uses less concrete than a traditional foundation, and includes insulation so no additional insulation is necessary. It’s also mould and pest resistant.
Durisol blocks, however, go beyond ICFs. They are completely petroleum free being made from 80% recycled soft wood waste that would otherwise end up in landfill and 20% concrete. They kind of look like a concrete brick, only the holes are filled with concrete, once the forms are set in place. Imagine putting a house together like constructing with Lego blocks, and are intended to be for contractors and DIYers alike. Tim told me that learning to build with Durisol can be a bit tricky in the beginning, but that once you get the hang of fitting the blocks together, the process is pretty straightforward.*
Construction: similar to lego blocks, it means that there is no thermal bridging — heat can’t escape through the wood studs which happens in a traditional stick-built home. Buildings are solid and durable. Unlike polystyrene ICFs, which are insulated on the interior and exterior of the concrete, Durisol blocks are insulated with recycled mineral wool on the external side of the block only, allowing the other benefits of Durisol to work.
Thermal mass: because insulation is on the exterior side of the building block, the concrete within the block is able to act as a significant thermal mass which means it can regulate heating, cooling and relative humidity within a building.
In order to perform the way they were intended, Durisol works best without a vapor barrier between the finished walls and the blocks, which means that a breathable finishing coating such as American Clay or limestone are excellent complementary materials to use. There have been studies done showing the benefits of Durisol, but adding a vapor barrier prevents the walls from doing their job. The concrete won’t be able to act as a thermal mass the way it’s intended, and relative humidity won’t be regulated.
Healthy air: Durisol blocks are made with benign materials so there is no off-gassing of any harmful toxins. Further, when built with a breathable wall finish, the structure acts as an extensive relative humidity regulator because of its hygroscopic qualities. For further information on the benefits of breathing walls, Durisol has developed this comprehensive report.
Mould, pest and vermin resistance. Because these blocks are made with 20% cement, they are mould, pest and vermin resistant. Indoor air stays healthy. Termites aren’t an issue. Neither are hurricanes for that matter. These blocks are so sturdy when filled with concrete, they are “severe weather” proof.
R-value. Durisol makes several different blocks, narrower ones with no insulation that are good for interior walls, and thicker ones with insulation for exterior walls. The smallest block with no insulation has an R-value of 8. The thermal blocks, that is, those containing recycled mineral wool insulation, range in R value between 14 and 28. Unlike a traditional stick-built home, there is no thermal bridging in Durisol homes. For more detailed information on the block’s thermal performance, read here.
What about the concrete issue? So yes, concrete is used in the building of a Durisol-built home. However, because of the other positive properties of Durisol-built homes, and that the concrete industry is constantly working on lowering its carbon footprint, it can be considered a cost of building for the time-being. Whether or not building with concrete is sustainable, well, that’s a whole different question. The sustainability of a building method implies that it can be repeated infinitely without decreasing or degrading future populations’ needs.
Oh, and if you’re wondering if this is some new-fangled green building material, the answer is no. Durisol has been around since 1953, so its buildings have a proven track-record.
Tim and Jan have convinced me of Durisol’s “green” properties, provided the blocks are used they way they are meant, and not just for energy efficiency, but in the construction of a healthy home. Thanks so much for speaking with me Tim and Jan!
For more information on Durisol, visit the website.
*In an earlier version of this article I explained that Durisol was not a DIY product and that specialists were needed to build properly with it. However, Tim emailed me to let me know that, in fact, Durisol is made for home installment and only on occasion is his building team called in to help with construction involving Durisol.