Horizontal roof strapping for ventilation?
I am building a 16’x24′ house in Alaska, 12/12 gable roof using 2X12 rafters, with a cathedral ceiling. A friend has recommended venting the roof by strapping the rafters horizontally with 2×4’s at 16″ o.c., thereby allowing cross ventilation from gable to gable. The roof would be sheathed on top of the 2×4’s. I haven’t been able to find any information on this technique on the web.
This approach is meant to improve on soffit-to-ridge venting using Cor-A-Vent-type ridge venting and AccuVent baffles. My concerns with that technique are that the insulation baffles create a vapor retarder on top of the roof insulation and the ridge vent won’t be effective when covered with snow.
Moisture issues are a huge concern here in the coastal rainforest, where winters are a constant mix of rain or snow and the cool summers don’t provide good drying potential. Also, using wood heat means that the interior temperature fluctuates considerably.
Fiberglass batts are the only insulation option in this remote area. If I strap the roof for cross ventilationI will have to accept the losses created through wind-washing. However, I would be able to fill the rafters completely, allowing R-40 insulation because I won’t need a 1″ ventilation channel.
Any thoughts on the wisdom of building the roof this way?