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Hi everyone,

I'm in need of some advice here. I have a cape cod style house with a dormer in the back that comes off the ridge and grades down slightly. The back has an a frame shaped addition. There is currently no ventilation anywhere on the roof. I've always heard that you should have a ridge vent and have had some people tell me when we do a new roof to add one. I've also had someone tell me that because of the shape and the location of the dormer I shouldn't put a ridge vent on because it would allow water to blow back up into the ridge off the dormer possibly causing moisture issues. The alternative was to put in box vents. It was suggested that I put 5 box vents in....one on either side of the dormer and three on top of it. Then put a normal ridge vent on the addition.

Also I've heard of ridge membranes? I know nothing about this, how does it differ from ridge vents?

Anyone with knowledge and experience in this area who could give me any advice would be greatly appreciated.








 

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I've also had someone tell me that because of the shape and the location of the dormer I shouldn't put a ridge vent on because it would allow water to blow back up into the ridge off the dormer possibly causing moisture issues. The alternative was to put in box vents.
Ridge vent requires a minimum pitch of 3/12 so if the dormer isn't equal to or greater than that than you shouldn't use ridge vent there. But I would use it every where you can and add static vents to the dormer roof only.

Radiant

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Thanks Radiant. So I'll come clean, this is not a diy project. I am having estimates and need to know who is telling the truth and who knows what they are talking about. My most recent estimate said the same thing you just did.

Thanks again
 

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True and accurate advice so far, ..... But there is a work-around for that situation which I have created.

By installing an Interior Baffle, such as a J-channel on the interior hollow copartment of the preferred ridge vent, which I conclude to be the Shingle Vent II, then you have eliminated the potential for water travelling iinward any farther than the J-Channel inside the ridge vent.

Ed
 
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