We began weatherproofing the roof this week, despite a continued beatdown from Mother Nature. The sky has been perpetually grey and in between the snow and rain, we’ve been rolling out and torching down a SBS modified bitumen membrane (I know you want to say that 5 times fast).

We’re using a product called TorchFlex, which is described as:

A strong reinforcing mat (polyester or fiberglass) which is coated with SBS modified bitumen. Styrene-Butadiene-Styrene (SBS) is a rubber-based chemical that endows the asphalt with some amazing qualities: superior elasticity, excellent moisture resistance, and exceptional cold weather flexibility. The end result is a long-lasting, durable membrane which can be applied to a wide variety of surfaces on roofs of almost any shape or design.

Installation seems pretty straightforward—The roof was first sprayed with an asphalt primer and then covered with sheets of fire-retardant protector board. Two layers of the TouchFlex were then rolled out and affixed by “heat-welding the membrane, fusing it to the protector board and using the same process to seal the seams.” Once that’s all complete, all of the aluminum flashing will be installed and everything will be caulked.

For aesthetic reasons, we’ve also foregone traditional eavestroughs in favour of a parapet with hoppers (or flow control roof drains). These have built-in strainers that will prevent large debris from clogging them, further reducing the likelihood of a leak. The rear downspouts will be connected to a rainwater tank (probably a Rainwater HOG) which will be used for irrigation in the backyard, and the other downspouts will direct their runoff to an underground drainage pit. This pit is also connected to our weeping tile, with the sole purpose of capturing the excess rainwater and allowing it to naturally dissipate into the soil (as opposed to, oh, running back into our house… which has happened to a few or our neighbours). Apparently we have incredibly dense soil that doesn’t absorb water particularly well.

We had also considered a green roof early on, however it was FAR more expensive than we expected. Beyond the plants themselves, you also have to account for the added waterproofing requirements, plus the increased structural demands (waterproofing and drainage layers, plus the soil, plus the plants, plus the water they hold). And let’s not forget that the plants need to be watered on a semi-regular basis, which meant we needed roof access. There are a few lower maintenance solutions, but they were all something we simply couldn’t swing (read: afford).

We’ve obviously shied away from a traditionally pitched roof, however one common misconception about the house is that the roof is flat. While it definitely appears that way from the ground, it actually slopes away from the structure at around 2 degrees. It doesn’t seem like much, but it’s enough to keep the water moving and prevent it from pooling.

The slope is actually quite pronounced when you’re looking at the lower roof from inside the house (mainly because it simply slopes from one side to another). However, the upper roof is a different story altogether. The roof has 2 peaks (on both sids of the clerestory) with each sloping away in 3 different directions. I’m not 100% sure how the framers figure out the various angles (and it’s actually hurting my brain just thinking about it), but I went up on the roof this afternoon and was amazed how well it was assembled. We’ve had quite a lot of rain over the last few days, but other than a little frost (and the snow that was falling from the sky) it was essentially bone dry up there. Of course the plywood sheathing isn’t exactly watertight and I assume a lot of water simply washed through the cracks, but there definitely wasn’t any pooling up there. I’d say that’s a good sign, no?

We had originally considered a product called PosiSlope, which is described as a “factory pre-designed tapered roof insulation and drainage system”. It’s essentially a large foam puzzle that gets assembled on the roof, with pieces custom made based on your drawings. Compared to strapping out the roof and sloping by hand, it’s assembled and installed in a fraction of the time, plus it has an inherent R-value… which is an obvious plus. Of course, it’s also happened to exceed our budget by just a few dollars. Sigh.

The next step is waterproofing the roof, although I don’t know the exact approach we’re going to take yet. I assume it’ll be a torch-down solution of some kind, but I could be wrong. We’re also planning on covering the entire clerestory (top and sides) with Ice & Water Shield to ensure it’s completely watertight. Well, as watertight as it can be… I suppose nothing is 100%. Regardless, I’m becoming somewhat paranoid about the clerestory leaking and I want to do everything I can to ensure it stays nice and dry.