Roof Ventilation for Cathedral Ceiling with no Eaves and 4×12 Ridgebeam
Hi there! I am building a studio in my backyard and am trying to find some information on the correct way to vent my roof.
I have a gabled roof with a 4/12 pitch. My ceilings will be cathedral with a ridge-beam that is 4×12 (so that the bottom is visible inside the finished structure). My rafters are 2×8 that currently join flush with the top of the ridge-beam. Because of non-permitting codes in my area, we were only allowed to build 120 sqft roof structure, so to get the most square footage out of the interior, we have no eaves on the rakes or back gable, with a 18″ overhang on the front. To make things a bit more complex, I have 2 skylights that will be centered to the structure. Right now my rafters are 24″ oc with two smaller gaps flanking the skylights, approximately 6″.
In order to properly ventilate, I know I need to use insulation baffles in the rafters, and that I need to vent each ‘shaft’. My issues are all the ridge vents I’m seeing are for 2x ridge-beams. Had I realized this issue before installing the rafters I probably would have just installed them to float over the top of the ridge-beam to create a gap for air circulation, but I didn’t so here we are.
I know I can buy drip edge vents for the rakes, but I’m not sure how to ventilate at the ridge, or how I baffle the two small rafter shafts the flank the skylight. Should I cut notches out of the ridge beam so when the sheathing covers it there will still be a gap for the air to circulate? Or do I stop the sheathing short and try to find a ridge vent that fits? I suppose alternatively I could buy shingle roof vents for near the ridge. The woman at Owens Corning I spoke to said I only need 3 linear feet of intake vents per side, but how does the air get from one shaft to the other? Do I cut notches out of the 2×8 rafters?
Thank you thank you for any advice here!!!
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