Ridge vents with/or box vent?
Hi,
I bought a house a few years ago. My shingles are old, so I want to refoof. A contractor came to give me an estimate and he said that the previous roffers did the “ridge vents wrong”, because I have a box vent already installed (is there a way to know which was installed first anyway?). He recommends covering the ridge vents, and he showed me a guide indicating that ridge vents should be closed when soffits and box vents are already installed.
However, looking online, it looks like ridge vents are more efficient and allow more warm air to leave the roof.
Should I give him the go ahead to block the ridge vents or ask him to reroof and leave everything as is?
Thanks!
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Replies
Proper soffit/ridge venting works great (correctly sized based on the slope of the roof and roof area with more are of the area in the soffits) there should be no reason to need more venting.
Not a big fan of box vents unless in heavy snow country, there is really no reason to use them over a soffit/ridge vent, they kind-of look like roof pimples.
Thanks for the info!
Marc,
It's an either or thing. There is no point having both.
As long as it is an attic, not a cathedral ceiling, and the box vents are well distributed along the roof near the peak, they will work fine. Ridge vents work with both roof types.
Having more venting isn't necessarily a good thing. The total amount of venting needs to be calculated based on the size of the roof. That venting should be evenly distributed between the soffits and ridge, or have slightly less at the ridge than the soffits, which will stop the roof from becoming depressurized and drawing air from inside your house.
What affects the roof more than the venting, is the amount of air that escapes into it through the ceiling. Air-sealing between the house and the roof space is time well spent, and increasing the insulation will make how hot the roof gets much less important.
Thanks a lot Malcom
I am not aware that anyone has studied the difference in ridge versus box vents. Intuitively, one would think that a ridge vent can better take advantage of the driving forces (wind and stack effect) than any vent down off the ridge, even just a bit.
You don't tell us your climate or the pitch of the roof, each of which can have an impact on both how much air flow results from wind and stack effect.
Regardless, I am betting that you will get more air movement from a ridge vent than a series of box vents.
Peter