On Aug 17, 5:15 pm, Paul Franklin
wrote:
On Fri, 17 Aug 2007 07:45:53 -0700, wrote:
I am having the shingles on my roof replaced. My roof has a ridge and
soffit attic ventilation system.

When I look up in the attic, I see there is a gap between the wooden
boards that make up the two sides of the roof. I assume the gap is
there for the air to flow thru. However the gap seems to be covered
with some black semi porous material right above the wood and does not
seem to allow a whole lot of air thru.

My question is.. when i look up thru the gap in the boards, should I
see some daylight that would tell me that there is a way for air to
pass freely? I can't see any daylight now and suspect air can't move
around that easily.

Well now think about it...if you could see daylight, what would
happen when it rains? :-) I know, you meant you would think you
should be able to see light...and I'll bet if you turned off all the
lights, you would see a little glow.

There are several styles of ridge vents, but probably the most common
is shingle over style. It's a flat woven plastic mat that gets laid
down over the gaps you mentioned. Then shingles are applied over the
top so it blends in fairly well with the roof. The air rises through
the slots in the sheathing, and then has to flow sideways through the
plastic mat until it exits from the thin edge of the material.

The material is made to allow a reasonable amount of air to flow,
while preventing insects from getting in.

It doesn't seem like much air will flow, but because it runs the whole
length (almost anyway, there is usual a foot or so at each end that
isn't vented) of the roof, it adds up to sufficient area to allow
enough ventilation.

In short, what you are describing sounds typical.

HTH,

Paul



There are shingles covering the roof vent to keep the rain out. The
shingles have been cut to fit the ridge.