Cape Cod Roof Venting: Deck Air and ShadowHawk

Greetings to all

For your review and comment.

The subject is a 1948 Cape Cod that needs a new roof as current one is 30 years old. The house is in Wilmington, Delaware which is 20 miles south of Philadelphia. Entire roof is architectural shingle without soffits. Original installation shorted drip edge on shed dormer. Now that it is older, shingles are cupping in back and water is running behind gutter. No water damage other than this. Mold exists but is minimal. Also, starting to lose shingles.
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There are 3 separate attic spaces.

The first one is a reverse dormer in front on the right with a 12 X 18" gable vent. Inside gutter is 7’ long and outside is 8’. It is 17’ wide and pitch is 6/12.

There is no access to the attic under this portion of the roof that anyone but a child could use. It is a crawl space under the dormers to the left. I plan to install intake vents at the gutters.

Next is the area over the garage on the left.



This measures 40’ long by 26’ wide. There is a Masterflow 1000 power vent for exhaust. I want to keep it and not install a ridge vent. There is also a triangular gable vent measuring 28" X 12" which I will have to block. The pitch runs 12/12 to 3/12 to a flat roof to 3/12 again. The front will take many different intake vents at the gutter. The back is a different story as the pitch is 3/12 eliminating Air Vent which needs 4/12 minimum. Lomanco Deck-Air installed right above the vent stacks will work theoretically, but I have received objections to intake vents on a low pitched roof due to potential for leakage. I could put venting at base of 12/12 pitch area satisfying code but the air volume under the low pitch part of the roof will be ignored.

Finally, the rear shed dormer.

It measures 19 X 40 and maximum height is 44" It does not connect to the dormer attic space in front. There is a second Masterflow 1000 used to exhaust this area. Again, I want to keep it and avoid a ridge vent. There are triangular gable vents on both sides; 28 X 12 " which I would need to block. There is also a gable power vent that is disconnected.

The one product that could make this work is the ShadowHawk by Air Vent. It provides 72" of NFVA per 40" in length. Seven of them would be just a bit greater than the NFVA of the fan (480 sq. in.) I believe it has passed the Miami Dade County wind and water test although the full test is unavailable on Air Vent’s web page. Efforts to get a copy have been unsuccessful. The Hip Ridge Vent’s Test Results are posted. Querying this site(Roofing.com) with respect to ‘ShadowHawk’ returns nothing.

I need some sharp eyes. What am I missing ?

I dont use this vent much because I don’t find homes with that style overhang. If I have a low slope and the eave will be gutter, look at Robert hicks starter vent. It’s a little different and it is a little tough to seam together and be appealing but it works and gutters will hide it.

Thanks for your comment. I will keep it in mind. You state that you have not used the ShadowHawk much. Does it perform well ? I am not too concerned how it looks as it will be in the rear of the house and difficult to see from the ground.