On May 4, 12:52*pm, "
wrote:
On May 4, 8:04*am, DerbyDad03 wrote:





I'm looking for opinions about what I'm seeing when I smoke test my new
ridge and soffit vents.

I had my roof replaced and a ridge vent was installed. I also had full
soffits vents cut and then covered with perforated vinyl. My soffits are
about 6" wide, so there's about 4" of perforated vinyl showing.

The roof is framed such that I have about 3 feet of slanted ceilings in
the bedrooms, and the crawlspace attic itself is about 4 feet from the
top of the ceilings joists to the rim.

There is bat insulation on the floor of the ceiling that extends part
way down the rafter bays towards the soffit. When I pull the insulation
out of the rafter bays, I can see light from the newly cut soffit vents..
The contractor said that the soffits themselves are free of insulation.

I installed 4 feet of baffles in each rafter bay, pulling them back
about 4" from the soffits, per the contractor's instructions. I then put
the bat insulation back in the rafter bay making sure the tops of the
baffles are open. The insulation does not extend more than 2' beyond the
top of the baffle so I know it's not covering the soffit vent.

Last but not least, I have a 12" x 12" gable vent at each end of the
house, which I have not yet closed off.

I bought some smoke matches to check the air flow and this is what I found:

The weather conditions were mid-50's F, thunderstorm, breezy. The attic
itself was fairly cool. I closed the access staircase so the attic was
closed off as it will be under normal conditions.

Holding a smoke match up inside a rafter bay near the ridge, there was
some movement up and out, but also a lot of smoke spreading down and
across the top of the attic. The was certainly no indication of the
smoke being rapidly sucked up and out through the ridge vent.

Holding a smoke match inside a rafter bay near the top of a baffle,
there was movement up the rafter bay towards the ridge, but it seemed
more like natural up flow as opposed to strong breeze blowing it
upwards. If there was a breeze, it was not significant.

Finally, holding a smoke match within an inch of either gable vent
showed significant outflow through the gable vent. It was literally
being sucked out of the vent at a rapid pace. If I backed away from the
gable vent 4 to 5 inches, the smoke just floated upwards towards the
ridge vent.

I suspect that I need to cover the gable vents, but based on what I have
described, do I need to be concerned that the soffit and ridge vents are
not operating properly? Do I need to wait until it's really hot and try
another smoke test?

Thanks!

I would not cover the gable vents. * IMO, it just serves
as more outlet area for the rising hot air. *Even if you
got some air coming in from one or the other, hard
to imagine that it's not going to help cool the attic.

Your tests on a 50F day aren't going to show much.
You want a day with temps in the 70s+ and full sun.

If you want to experiment, try holding a smoke source
at the soffit vents with and without the gable vents
blocked. *I'll bet you can't tell any difference.- Hide quoted text -

- Show quoted text -

Testing with the gable vents blocked was going to be my next step...I
just didn't have time last night.

I'm waffling about covering the gable vents. In talking to both
contractors and others, the majority say that they should be covered
but its sure not 100%.

The guy that actually did the roof basically shrugged and said it
shouldn't matter...it was up to me.