On 6/6/2008 12:05 AM Aaron Fude spake thus:

On Jun 5, 9:27 pm, Red Green wrote:
Aaron Fude wrote in news:187657b9-7bc1-44d2-b481-
:

What's the point of caulking the roof flashing for the exaust fan
vent?

Specifically, I'm talking about what takes place at 2:20 in the
following video:

http://youtube.com/watch?v=IrwWOW9RE3Q

It seems to be protection against the water flowing up. Is this done
to protect agaist the moisture drawn up by capilary forces? And in
that case, are the shingles themselves caulked?

Thanks!

You've seen other replies with good reasons. Another is ice. Ice builds up
in places then backs UP the roof and UNDER shingles when it can.

All of the replies make perfect sense to me.

The one thing I'm puzzled by is that all of those would also be good
reasons for caulking each individual shingle as well. Yet, that's not
the case. Is that becuase there's plywood under the shingles and a
hole under the flashing?

Well, it's been a long time since I handled any shingles, but I remember
the asphalt ones had sticky strips on the bottom near the front edge
that would bond with the shingle underneath; does that count? Of course,
neither wood shakes nor tiles have any such sealants, and they seem to
work fine.

I have a customer with a practically brand-new (OK, 10 years old, but to
me that's brand-new) million $-plus house, who reported a leak around a
light fixture in a room. Walked the roof, which was in just *perfect*
condition; nothing loose, not a crack where one could see a chance for
water getting in. Turned out it happened during a storm this spring
where high winds drove rain under the shingles. In a case like that,
there's not much that's going to stop *some* water from getting in somehere.


--
The best argument against democracy is a five-minute
conversation with the average voter.

- Attributed to Winston Churchill