Another Ventilation Question

Hello all -

I have 4 split level houses all the same structure and roofs. The roofs are split roofs with the front 15 X 40 (pretty good pitch) with a small gable, since the ceiling is cathedral here, there is no attic space except for the gable area. The back flat part is 14 X 40 (very little pitch) and there is about 18" from the ceiling dry wall to the roofing deck.

I am trying to figure out the best possible ventilation for them as I am getting new roofs on all. I had one done already and the deck was in great shape (especially since it was a 22 year old roof) I do not know how old the deck is but I am assuming it is the same as the house 45 years. No decking material needed to be replaced. The deck is made of of 4X1 boards.

The old vents were just regular 12" galvanized (I believe) vents (U shaped if you looked at them from profile) - do not know the name, but they were just these curved U vents with a screened intakes on the bottom. I believe they were the original to the house.

The new vents they put on the one house are like round aluminum tubes only 4" in diameter and tapered at the top. Kinda like the silver round vents you see on many commercial flat roofs just much smaller.

There were 3 vents (4" X 12" at the opening) on the roof before the tear off and now there are 3 of these 4" vents. It does not seem like these are enough ventilation especially compared to what was there.

Some background: this is a pretty straight forward roof, put too pieces of cardboard together, one on an angle (front of roof) the other flat (back part of roof where vents are) of course with the gable in the front part. Hence you have got my roofs shape.

There are no eave vents (no attic in front, no eaves in back) and the low slope of the flat roof does not allow for a ridge vent (according to the current contractor). There is a triangular opening/vent in the gable front.

I still need to get the other 3 roofs done. I want the venting to be the best possible venting without redoing the roofing structure.

HELP - What do you all think - should the 4" tube vents be replaced or are they ok.

ANY INPUT WOULD BE GREATLY APPRECIATED. Also any quality resources anyone could refer me to would be great - internet or other.


click here for more information from GAF. It should answer your question