insulation & attic ventilation

Phil_8

House built in 1941. Full hip roof (no gables), no sofit vents and because of the large chimney in the center, not much room for ridge vents. Solid brick/masonery walls. Beautiful old cast iron radiators. Two questions: (1) what is the best method of insulating the walls? If we fir them out should we use (a) 3" fiberglass batts, (b)some of the newer polyiso spray in insulation or (c) rigid foam board glued to walls? (2) Any ideas on the best method of getting outside air moving under the roof and above the attic insulation. Could easliy add soffit vents but only about 3ft. each side of chimney for ridge vent.
Also, would it be worth the trouble of moving the radiators back into the room a few inches and insulationg behind them or just have them slightly recessed in the new wall?

Your thoughts appreciated.

Phil

UniR

Phil, a geographic location is really needed for questions like this.

However, if you can get a good price on poly spray then that is the way to go. It would give you the tightest walls by far. It may be as good a batt insulation without having to fir out the walls and then having to move rads out and lose room size. Foam board is hard to shape into the stud cavities. If you are using batts use rock wool like Roxul. "R factors" are calculated at 75°F for some strange reason and rock wool has far better insulation poperties than fibreglass when it is cold out, is essentially fireproof and isn't comprimised by moisture. Place your vapor barrier according to your climate.

For the roof, vent near the peak and put in some soffit vents all the way around. Anything is better than nothing and each in turn will not remove as much summer heat as the last one installed. Ridge vents can sometimes let in moisture so I wouldn't worry too much about that. Just make sure that the soffit vents are done as much as possible all the way around. The vents near the peak should be as large in diameter as you can make them fit between the roof trusses. An 8" diamter opening has almost twice the area of a 6" diamter opening for example...

Good luck.

Northwoods Tinner/wethead

Attic ventilation and wall insulation

Not knowing exactly the situation, I would recommend a house attic fan with a thermostatically controlled unit and add proper vents where possible. Insulation: If possible, have a contractor drill holes from outside of building and blow insulation in and plug holes. P.S. For proper square foot ventilation air flow, I recommend looking in the Broan catalog.