Hi guys,
I enjoy the show and wish my old American Four Square’s projects moved along as rapidly as yours. I’d like to insulate my attic ceiling, too, but the roof leaks (even into the walls when the ice dams) so I’ll need to replace the slate roof first. Good thing we didn’t blow insulation in the walls already because it would be soaked now! I waited because I have to replace the knob-and-tube wiring before I can insulate the walls.
Anyway…question: Your hip roof doesn’t seem to have any ventilation. My contractor says that the manufacturer will not warranty the shingles with out proper venting of the underside of the sheathing. How did you address this concern? I have zero bays that run all the way from the soffit to the peak of our 3-dormer hipped roof.
BTW, I do hope to heat/cool our nice roomy walk up attic.
Stephen Fixx from Ohio
__________
Hi Stephen,
Great questions. You really have a terrific grasp on what’s going on in your house. Very refreshing! And this sounds like familiar territory for us. The answer to the venting question is 4-fold.
1. We do have soffit vents.
2. Even if we didn’t the gaps between the crown and the bottom of the roof deck that you can see light pouring through adds to the volume of air passing under the rood deck.
3. There is a 1 1/2 inch gap between the back of the insulation and the bottom of the roof deck for air to pass.
4. We have pot vents in the peak to evacuate the air that I’ll upgrade to a SunRise Solar attic fan when I put on our DaVinci Roofscapes polymer slates in the next few weeks.
More: Your attic space, of course, was never meant to be occupied. And while you may be able to drill 3/4 inch holes in the rafters (check with your code official to see of this is kosher) to keep air moving and prevent mold, your best case scenario might be closed-cell spray-foam sprayed onto the bottom of the roof deck, a la Mike Holmes. Not cheap, but you don’t need to vent it.
Check out our attic renovation in our American Foursquare. We converted the unfinished space into our MyFixitUpLife office.
Thank you so much for writing and your kind words about our show!
Update from Ohio:
We finally had the roof replaced last Fall with asphalt shingles and guess what? …The manufacturer will provide a warranty for an unvented “hot roof” system! Because, they now sell the shingles and the spray foam insulation 🙂 After much research and consultation with my roofer we added 2 inches of rigid polyisocyanurate insulation over the bare roof deck, followed by 5/8ths OSB screwed down and the rest was conventional synthetic felt and ice guard. We haven’t sprayed the underside of the roof with foam yet (the pink fiberglass is still loosely in place) but we have noticed the attic is appreciably warmer this winter. My research showed that the rigid polyiso’ insulation has several benefits: For Northern climates it allows higher R-values to be met in shallow rafter bays; it moves the dew point further from the attic ceiling, It’s cheaper than spraying more inches of closed-cell foam, and the number one reason…it provides an extremely effective thermal break. BTW, I would have loved to put on a DaVinci roof, but the budget simply wouldn’t allow it. Keep up the great work!