I have an old house w/ 2×10 joists 16″oc, 2′-4′ crawl space, lots of
wiring/plumbing obstructing bottom of joists, and a seasonal rodent
problem from the surrounding fields. The rodents, cats, & squirrels love
to nest in the existing fiberglass batt insulation. It has been
recommended to place hardware cloth at the bottom of the joists to both
hold the insulation and prevent critters from nesting.(this would be
extremely difficult due to existing wiring/plumbing obstructions) I
currently have an ~8 mil sheet plastic vapor barrier at the bottom of the
joist and kraft paper backed fiberglass batt insulation in place (but
damaged/soiled due to critters). I have been advised two conflicting
strategies. That the correct insulation installation is to have vapor
barrier on top side next to the flooring (most local contractors
recommendation), and conversely, to have the vapor barrier towards the
ground, the open face of the batt facing the floor above (by a
designer/insulation specialist). Being in Austin. Tx. we have both cold
fronts with condensation worries from moisture coming from inside living
space, and hot moist conditions with worries of condensation on the
outside of living space.
Which is correct?
Is sprayed closed cell foam insulation appropriate?
Are there other alternatives?
What about vapor barrier on ground?
Mold is a big worry.
Replies
So what is the problem? other than you need to keep out the critters?..if it aint broke dont fix it.
Where I live we put the insulation's vapor barrier toward the living space, and the insulation is pushed up against the floor so that there is no airspace between the insulation and the floor. It is held in place by insulation support wires that are roughly the diameter of a coat hanger. As far as your critter problem, well, my first thought is that if you have cats, and rodents, the cats must be lazy... unless your crawl space is were the cats dine or a regular basis... :^) Is the crawlspace perimeter enclosed or open? Maybe the perimeter is where you need to put up your critter barrier?
A plastic vapor barrier on the crawl space floor is pretty much a requirement as it prevents moisture from the soil from migrating up into your house.