I spent the 3rd and 4th of July working on the pumphouse roof. Dennis and Matthew came to help again and as usual were lifesavers!

The roof design is a little complicated. I was trying to achieve the most insulation in the least depth because I didn’t want to infringe too much on loft headroom. I’m pretty tall and I didn’t want to bonk my head every morning. So I decided to use polyisocyanurate rigid foam insulation (say that five times fast). The design is something like this: three and a half inches of foam between the 2×4 purlins, then a 3/4″ continuous layer over top. Then 1×3 wood nailers fixed to the purlins, and then half-inch OSB decking with a radiant barrier. Over the decking is 30# roofing paper, and finally corrugated steel. The 1×3 nailers provide a solid backing to which the decking is attached, and also provide an air space so the radiant barriers on the OSB and the foam insulation can improve the insulation value. I expect the finished roof to be near R-30 and be only 5-1/2″ inches thick below the steel.

Pumphouse - now with roof!

Pumphouse - now with roof!

We managed to install 2-1/4″ of foam, the 1×3 nailers and OSB, and the roofing paper. The roofing paper is waterproof so it should stand up to the monsoon rains without leaking.

The gable ends are still open (we screwed some sheets of plywood to reduce the amount of rain entering that way) and one window is yet to be installed (we covered that opening with scraps of foam insulation). So it isn’t weathertight yet, but very close.

Wifey and I are headed to NYC for a week to attend a friend’s wedding. So the pumphouse will have to wait a little while. When we return, hopefully I will be able to put up the steel, cover the gable ends, and install the last window. After that it’s all trim and interior work (like the ceiling and loft floor).

There are lots of pictures of the whole odyssey on my Facebook photo gallery.

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