Air Vents


#1

I have six passive air vents and local roofing companies say I should increase the number. Should I put in more vents or replace the existing vents with ones that have more air flow capacity? Also, what do you guys think of Duraflo products. Oh by the way, my house has perforated aluminum soffits so "intake should’nt be a problem.


#2

Ridgevent is more efficient then ‘Box’ vents. Just because you have the right soffit vents does not guarantee you have have proper air flow.


#3

Wow! I didn’t realize my soffits might not privide enough intake. Any suggestions on how to improve this? As far as the ridge vents, they don’t seem to be used up here on the Candian prairies. Also, my roof is chopped up into a quite complex line. So, any suggestions what my best bet would be for box vents, install more or replace the existing ones with units that have more free net area (Duraflo 75’s instead of 50’s)?


#4

What I was trying to say is, sometimes when perforated soffit get put up. The installer neglects to cut out the old wood soffit. If your home is ‘newer’ they may not have this problem or they could have been installed correctly. Also, in the attic is the insulation blocking the soffit intake?

You can never have to much ventilation. Is yours enough? Six box vents would be adequate on a small house. I’m not sure the size of yours.

Local roofing companies say you need more vents. Are you looking into getting a new roof? Are you just having your ventilation system checked?

I’ve personally never used Duraflo products, so I can’t comment on their products.


#5

House was built in 1994. I know the soffits have no wood under the vented aluminum. Sq. footage is 2,169. Original venting was based on the "1 to 300"rule (no cathedral ceilings). The box vents are evenly spaced near the top of the roof line. I’m putting on a whole new roof. Local roofers feel I need to double the amount of box vents. It would be hard to mount all these boxes without placing some on the front of my house hence my question about using bigger boxes.


#6

You definitely don’t want boxvents on the front of your home.

I would still recommend the ridgevent.

Different regions are used to doing it the ‘local’ way. I’m sure that if you said you wanted ridgevent, they would gladly install it. As for how close you can put boxvents to each other, I’m not sure what I would do without seeing it.

If you or your roofer insist on box vents, then yeah, go for the 75’s.


#7

Thanks RooferR. I’ll definitely talk to my roofer about the Ridge Vents.


#8

You’re welcome.


#9

Just when you thought I was done I came up with one more question. My roof is quite steep and currently has “slant back” box vents located near the peak. If I do have to continue using box vents should I stay with the slant backs or would square models be okay.


#10

Either would be fine. Slant backs have the opening more closed off, but a small flange under the shingle’s.


#11

On a steep roof slope, the slant backs are supposed to be used to diminish the potential for water cascading into the neck of the vent that is stubbed through the vent hole where the air flows.

The tapered rear solid section prevents that from being a potential issue.

Ed