Unvented vs. vented roof
I live in the Pacific north west, and will be building a home off the cost of Vancouver island this fall. The house is small, 700 square feet, with a 1 n 12 pitched roof as the design. We have not started construction on the house as yet and we want to deal with the roof in a way that will, of course, provide the best of all worlds.
This is our issue: we want to create an open joists ceiling in our home. Right now the house is 26 feet wide, with a supporting wall located about the 12 foot mark that runs the entire length of the home, that length being 28 feet. The roof joists will sit along the shorter part of the home, meaning width as opposed to length. I want to expose the joists, designed currently at 2 x 10 at 16" o.c.
Since we want to have exposed joists, and we don't want to have a really thick roof above that we were looking at creating an unvented roof, or warm roof system. I have done extensive research and in Europe the warm roof system involves: joists, sheathing, membrane, insulation (rigid) sheathing again, and roof material - in our case standing seam metal roof.
The insulation currently is slated at a polysio (sp) rigid insulation, 6" to attain R-32. The information out there is very contradictory. Some say yes to this system, some say you still need to vent, our engineer told us we can't have insulation next to organic material unless it's vented, that is so contrary to warm roof systems I'm wondering what is happening.
If anyone has some information to add to this to clarify that would be great.
I guess the biggest concern is getting the permits to build this kind of roof and if is even doable. Has anyone heard of the warm roof system used in Europe? Why is it so popular there and so hard for me to find information on it's use here in North America. I seriously must be doing something wrong in my research.
Posted Sep 1, 2014 7:12 PM ET
Edited Sep 2, 2014 6:59 AM ET
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