: On Sat, 16 Jul 2011 18:41:41 +0000 (UTC), Andrew Barss
:>I should say it will be a LOT easier if I don't need to install additional
:>air flow in the attic -- soffit vents would be difficult to install, and I
:>have read very mixed reviews on e.g., attic fans (fire hazard, noiuse, :>effectiveness).
: Tile roof? I have large gable vents (2), soffit vents and thick
: blown-in insulation (Nevada) and it still gets hot up there. In lieu
: of electric power vents, perhaps a solar powered unit on the gable
Nope, asphalt shingle roof, over softwood (probably pine) sheathing.
There are two of what pass for gable vents here -- meaning there are
a few brick-sized gaps on either end of the house, toward the top of the
peak. I think if I were to utilize them I'd need a larger hole
on each end, which means getting a decent mason who knows what not to remove,
and they're thin on the ground here.
So it seems like I have these options, after blowing in the insulation
(we investigated getting foam sprayed on the underside of the roof, which
is the approach I'd like to do, but the price is prohibitive), and after
completelty sealing the ductwotk (it's in the crawlspace) and ceilings to
prevent airflow from the cooled living space up to the attic:
(a) seal the attic completely.
b) Installing a ridge vent along the length of the house, and figuring
some way to get outside air into the crawlspace. Soffit vents are pretty
much out (the roof rafters end right on the header plate sitting on top of
the brick walls (common feature of c. 1940s housebuilding here), so soffit
vents would require removing the current fascia, attach rafter extensions,
building out the roof, closing the extensions off with new fascia and
proper soffit boards, and putting in vents.
I have seen mentioned (but not in detail) intake vents that can be mounted
low down on the roof (near thre bottom of the attic air space, right above
the unsulation line). Anyone know what they're called? This would get
the day's heated out out faster, and would (I think) lessen the heat load
above the new insulation in the attic.
c) Installing a powered (possibly solar-powered) attic vent fan.
-- Andy Barss