I know we have a few contractors on this list, so I have a question
regarding the use of plastic vapor barriers on the interior of the home.
I embarked upon renovating / building my addition with a copy of George
Nash's DIY House Building, which was previously recommended on this list and
also had good reviews on Amazon. Lots of good info and he recommends using
a plastic vapor barrier on the interior walls and ceilings to keep interior
moisture from penetrating the walls and getting into the insulation and the
backside of the OSB.
The building inspector this morning, probably already pissed off about being
made to work when it is snowing out, was pretty against the idea... not to
the point of telling me I would fail my inspection, but to the point of
saying it will create a mold problem and actually create condensation in the
wall cavities.
The outside of the house is already Tyvek'd and sided, so no moisture can
get through the exterior, but as I understand it, Tyvek does allow moisture
through its backside (it only works one way). The ceiling in the addition
is cathedral in all rooms, and there is a ridge vent, so the entire roof is
already ventilated.
The inspectors in this town are really old school. I hate seeing window and
door caps stuffed with insulation, because it will either be ineffective
because the insulation is packed too tight decreasing the R value or the
insulation will be too loose and be ineffective... I have never seen anyone
be able to cut a 5/16" strip of insulation well enough to make a perfect
fit. So I like using the DAP based Latex foam sealant, 100% air tight, and
also the rate of expansion is governed by the chemicals... so you can't over
pack it... you just cut off the excess. (and the DAP Latex stuff does not
harden and break your windows).
Also want to rant about Insulation Manufacturers and Building Supply places.
What is the point of offering high-performance insulation, R15 (3.5") / R23
(5.5)" / R38 (10.5") rated materials in their product catalogues. If they
are not stocked anywhere and no one is willing / able to order it. What a
waste... I ended up with R13 / R19/ R30 which is subpar to what I wanted to
use.
Anyhow, any advise on the vapor barrier issue would be helpful. I can't
understand how keeping moisture out of the wall cavities is a bad thing, and
the only way you will get condensation back there is if moisture gets
through the drywall and insulation to begin with (without a vapor barrier).
TIA,
Kai
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