Roof venting

[krisway]

Once I get my ceiling done, I will be adding batt insulation to the attic. I will need to add roof vents, but just wondering how many vents are needed? My garage is 16' x 36'

 

[JakeKohl]

are you talking about sofit, gable, box roof (cutout), powered mushroom, or ridge vents?

 

[krisway]

box roof (cutout)

 

[nwav8tor]

You need 1 sq ft of vent area in the attic for every 150 sq ft of attic. If you will have BOTH soffit and roof/gable vents then you can use a 1:300 ratio instead. Ideal area split for soffit vent area to roof vent area is a 60/40 ratio.

Not an expert, but have done some research,
Paul

 

[Tim The Tool Man]

Depends on where you live, the construction of your building, among other things. Generally the idea is to pull outside air from your eves or soffit where the roof meets the house and expel it at the ridge of your roof. This can be done naturally with vented soffits and ridge vents or mechanically with soffit vents and a mushroom type fan located centrally near the roof's peak. Gable vents and fans are the least desirable option because they don't effectively pull the air away from the the eves or soffit where the roof meets the house but may be your only option with existing construction.

How much venting do you need? Again depends on where you live and the construction of your building but generally the more the better. If you are located in someplace like Portland and experience excessive moisture then more might not be better...

 

[jvitez]

I printed off this link for a previous post on GJ, so I'm not taking credit just passing it along. I found it very informative.

http://www.buildingscience.com/documents/published-articles/pa-crash-course-in-roof-venting

 

[krisway]

Any tips or links to show how to install these box roof (cut out) style vents?

 

[RoofDude]

I printed off this link for a previous post on GJ, so I'm not taking credit just passing it along. I found it very informative.

http://www.buildingscience.com/documents/published-articles/pa-crash-course-in-roof-venting

Pretty cool info in that link.

x2 on the importance of venting. Many times Ive replaced sheeting on homes that did not have leakage. Improper venting led to dry rot.

Im a fan of ridge venting. I believe it to be the best bang for the buck, when combined with effective intake (soffit ventint).