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Too hot in attic and upstairs rooms

robertman | Posted in General Questions on
I recently moved into what had been my father’s Bay Area house, which I inherited when he passed (built in 1906). The house is in Oakland so no air conditioning or need for it. There had been a rat problem in the attic so I first plugged any entries and set traps. After months of no rat droppings or trappings, I started to clean up the attic, replacing the insulation (which was full of signs of rat life), putting sleepers on the joists (2×4 bringing them to 5.5″ in height) and installing roxul r-23 and .5″ ply flooring. I will use the attic for light storage. I am pretty much done with that and now want to tackle the problem of how hot the attic and upstairs rooms get (about half attic, half converted to living space probably in the early 60’s). My father had the roof replaced about 15 years ago and they stripped the roofs and put ply over the skip sheathing and then new 40 year (I think) comp shingles. They did not upgrade the framing so it is original full dimension 2x4s 32″ on center. They did put in soffit vents (which they left completely covered with old shingles etc and which I have now unblocked) and ridge vents and there is a gable vent on one side and an attic fan at a gable vent on another (one on south side of home and other on west side). I may change these to windows but more on that later. There is about 5’9″  feet of head room at the ridge of the attic.
Obviously the roxul between the joists will do nothing to keep the attic or upstairs rooms cooler but should help with the main living area downstairs. TO combat the heat, I am thinking of trying to set up a tunnel effect in the rafter bays for the vents and reflect some of the radiant heat as a starter. What I am thinking is to but 3/4″ or 1″ spacers at the intersection of the rafters and skip sheathing and then a similar spacer in the middle of the rafter bay and then stapling a radiant barrier to that. I may try to put a 2x at the base of the bay to force the incoming air into the chimney effect (up and out the ridge vent). I have read that there is much false advertisement etc about effectiveness of radiant barriers but I think this is the type of application they are designed for. Are radiant barriers effective for this and does this sound logical? I may at a later date try to put mineral wool board (like cavityrock or rockboard) on the underside of the radiant barrier which I think would help for cold and noise transmission (i hear the above ground subway and the freeway, especially at night). After the radiant barrier, I’d have approximately 3″ of rafter left. I could use foam but think it’s inferior in terms of fire, ecological, and noise problems. 
Also does it make sense to replace the gable vents with windows which I could keep closed in the colder months and which would help keep noise out (noise is much worse in winter when overcast)? And I could also pop a couple of operable 2′ by 2′ skylights on the north and west sides of the house (1 each). I can do much of the work myself and now have free time because I am required to  shelter in place. I also have building skills. 

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