![]() at the same height as before but with about 15 inches of insulation up to the vent baffles. batts but now the heat is really pouring down I am leaning toward r13 + unfaces r30 plus radiant barrier and battens and finally some kind of ceiling. My original plan was to insulate with r13 f.g. Cutting through the roof deck plus 2 layers of asphalt and tar was a real joy but if i had to do it again I would angle the sawzall blade to just cut the wood because the asphalt was brittle and breaks way easier than it cuts. And there is no moisture in the Sonoran desert so insulation needs to be maximum. This fixed the two split rafters but I can forget about a second floor. This method would save me about $50 in rafter vents because I could only use half the number, but will it still work optimally if each rafter space has 1 soffit vent that is 16''x4''?Īfter examining this framework closer i determined the 2圆 is underutilized as a Support for the sistered rafters so I added two supports between it and the furring strip i added for insulation. The picture on the HD site (attached) from the manufacturer clearly shows centering a single vent in the middle of the rafters with a few inches on either side unvented if the vent is too narrow to span the whole space and a rafter baffle is either 14'' or 22'' wide, then should I put 14'' vents side by side, using 3-1/2 vents x 2 per rafter space, so the whole space is vented, or use a 22'' wide vent with 3'' on either side that will not be vented? Will it matter as long as the insulation isn't flush against the bottom of the deck? This porch is basically going to be a low slope cathedral ceiling when I'm done and I'm trying to mitigate the oven effect with some roof ventilation. The question I have is when the rafters are 30'' O.C. Yes, the owner used knotty pine walls inside a porch so it gives the impression of being finished, but the walls had no insulation, no sheathing (siding was board and batten, now it's Truwood), no house wrap and the windows were framed into the 2x4s that were all 30'' on center. The last photo is of the porch interior and the low plywood ceiling. This is hard to visualize so I included an exterior photo of what I have discovered about the 3 roofs. Were they cooking food in the attic?) This is southern Arizona/northern Mexico at 5000' so that might've had something to do with it. (I don't quite understand why someone in 1955 would deliberately build a roof over another roof with the intention of eliminating all ventilation of the canopy air spaces. I think the venting math for a 900 sq ft roof is basically 1.5' venting at each soffit and 1.5' venting at each gable. So, I cut into the porch roof 'ridge' and actually vented air (pictured) into the canopy air space, that is vented with 12''x12'' gable vents until I can gather the material for a ridge vent. Oddly, the porch roof connects to the adobe house UNDER a secondary roof that is basically a canopy built over a parapet roof and transitions to the original porch roof closer to the eave. The walls are insulated now and I'm looking at the roof that had no venting at all until I cut about 8 feet of the soffit to add 9 vents. ![]() I'm trying to insulate a room that I think started as a 23'x 14' wide porch in 1955.
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