It Looks Flat, But It’s Not

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.




