The felt paper _can_ help prevent an ice dam leak on a pitched roof that has
poor ventilation and/or insulation. It's a last line of defense. And the
builders can't always get the roofers or siders on the job as quickly as they'd
like, so they temp it over with asphalt impregnated felt. I like 30 lb. for
roofs, much safer to walk.
>Joe job2 wrote:>What is the logic for using tar
paper behind vinyl siding and under
Vapor barrier is designed to keep moisture inside the heated space. It's
vapor barriers _outside_ the studs which foster decay by retaining escaping
moisture and allowing it to condense under the tarpaper. Put your _only_
vapor barrier on the heat side to slow loss and possible capture through
And vent your attic to keep condensation under the necessary water shield
from rotting your underlayment.
All depends on the climate you're in. I can't remember off the top of my
head right which way it is, but I think it's in the north you want to
keep moisture in, but in the south you want to keep the moisture out.
But I might be wrong and it's the opposite.
That must come as a shock to someone from Microsoft, but there's still
some diversity in the world.
These rules specify the need for a vapour barrier on the warm side of
the insulation. It doesn't forbid having one on the other side, should
this be needed.
If you make the external weatherproofing of small tiles or shingles,
then you use a continous sarking underneath it. This shouldn't ever
need to keep water out (if it does, your roof is broken) but it is
needed to keep the water vapour that will penetrate a normal tiled
roof out of the roofspace.
I admit I know nothing of vinyl siding. It's a heathen practice, but
then most US house-building practices are. I spent a couple of
weekends with your Habitat people once - a great idea, and very
interesting, but a bit horrifying to a bricks-and-mortar European.
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