Metal roof over timber structure

Don Kenney
9/13/2013
I get a lot of conflicting information on the type of roof I should install on my new home. It is a timber structure that I plan to first apply 2x 6 t&g covered with ice and water shield Then I planned to lay down osb screwed through the 2x 6 into the timber truss. This would address the diaphragm effect of just the 2x6. Then I would install 2 layers of 3 inch polyiso with staggered seams. I then planned to lay 2x4s flat directly over the timbers.covered with 5/8 sheathing. These would be screwed through the entire system into the timbers. The 2x4 between the foam and sheathing would allow ventilation I was not sure of the added advantage of then installing horizontal 2x4s . across the vertical 2x4 so I left them out. I would then cover the 5/8 sheathing with 15 # felt and finally the metal roof. Is this system OK
Info @windowsonwashington.net
An informed customer is our best customer.
9/14/2013
Seems more than just fine. That is a very solid approach. I would use synthetic in lieu of felt just because it is designed to match the lifetime performance aspect of the metal roof. What is the pitch and will the roof need to be walkable? The horizontal 2x4s mostly a necessity if you are covering and using decking.

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