Greetings from Vancouver Island-

I am in the planning stages of converting a 8′ X 30′ NE facing covered deck to living space on my 1970’s mid-century modern home here in the Pacific North West. It has a 6 year old torch-on mono-pitch roof, 1/2″ : 12 pitch,  2X10 rafters, 2 @ 4″ thick glass batts. The porch is at the high (ridge) end of the roof- there’s about 28′ of roof below it.

Rafters run both parallel and perpendicular to the pitch: in the area I’m concerned with, the main house rafters run perpendicular to the ridge and the existing porch rafters run parallel, bearing on timber beams.  

The rim rafter (separating house conditioned space from covered porch) has a series of 1″ holes drilled through it, presumably to allow ventialtion. The porch soffit is perforated aluminum. 

When I enclose the porch, the aluminum soffit goes away and that method of ventilating goes with it, and so I’m looking for ways to replace it. Since the porch rafters run parallel to the ridge, warm air entering the first porch rafter bay from the main roof would have to travel as much as 30′ before reaching a soffit vent at the adjacent overhang. I don’t know if that’s a problem. Other options would be to: 1) figure out a way to add ventialtion to the adjacent overhang- perhaps through the fascia (1X8 over 1X12 cedar), or 2) add roof vents- which I’d prefer to avoid, as cutting in and patching the 2-ply torch on is expensive and potentially problematic. Although I could spring for it if convinced it’s the right thing to do.

Lots of things can happen in an ideal world: that’s not the world I live in. I want to do what’s right for the longevity of the roof but I can’t break the bank. Any learned advice will be welcome; frugal soultions will be met with enduring gratitude..

Thanks,

Chris