I am installing a new composition shingle roof on a 2.5/12 shed roof which is attached to the back of my home over the kitchen and dining area. The cathedral ceiling in made of 2x6's with 2x2 furring strips attached to their bottom- I suppose the person who installed the system figured that made it OK to use R30 insullation!. I have removed all rock and insulation and will replace water damaged decking once the existing shingles are removed tomorrow. The rafters are solid blocked with 2x6 to accommodate nailing between sheet edges. There are three blocks per rafter bay including the one at the wall plate. Since I have the roof completely opened up i am considering adding a ventilation path to the system. I have read a lot of different posts regarding how to vent a roof such as mine and after digesting it all have concluded that the best way will be to cut and place vents in the blocks at the wall plate and then drill several holes in each of the other two blocks. Where i am getting a little stuck is what to do with all that hot air at the top of rafter where the roof meets the wall. I am somewhat resistant to products like cor-a-vent just because of the slight pitch and very light but predictable snowfall that i get at my elevation. I am considering drilling holes between the rafters toward the top of their run and then installing two or three equally spaced roof vents. Another option would be to avoid additional penetrations and place vents in the soffit at rake. If anyone out there has had success with a project like this I would greatly appreciate any insights. Also with the existing rafter depth of 7in I am considering an r19(6.5 inch thickness but easily expands to 7in) batt insulation- if my holes are the top of the rafter blocks will the insulation prevent air flow?
This is my first post so if I have made any mistakes in protocal i apologize in advance.
thanks
Robert
This is my first post so if I have made any mistakes in protocal i apologize in advance.
thanks
Robert