roof cap for kitchen vent?

[James Baker SD]

I know this is a little off topic for woodworking, but I am installing an over cooktop exhaust ventilation hood (had to cut some plywood if that makes this a woodworking project :) ) and I am a little lost on what to place on top of the roof to cover the duct from the hood.

I don't want rain coming in (it will go directly into the hood's fan motor), nor do I want smoke from the all too frequent wild fires to come in through this vent. But a lot of grease (hopefully) will get sucked up into the duct so I fear a hinged door on the vent cap might gum up and not move. Also I hate to waste the fan motor's limited power (it cannot compete with my Oneida DC) to force open a closed door.

What have others done when they installed exhaust hoods? Thanks.

James

[ray hampton]

I did not install the vent cap myself but they are made from 2 or more pieces, the bigger piece that cover the vent pipe and and the piece that will snap into the vent pipe

[Chris Padilla]

I wish I my stove hood vent had a door on it: cold air from outside flows right in if the fan isn't on.

My vent, however, is on the side of my two-story house so rain entry isn't an issue. It does have a mesh/grid on it to keep critters out.

[Bill Rogers]

From what you are describing you want an APV (all purpose vent). You can get these at a roofing supply house or possibly one of the big box stores. What type of roof covering do you have?

[James Baker SD]

From what you are describing you want an APV (all purpose vent). You can get these at a roofing supply house or possibly one of the big box stores. What type of roof covering do you have?

Composite asphalt.

[Bill Rogers]

Composite asphalt? Do you mean that you have aspahlt shingles or do you have a built up roof?

[James Baker SD]

asphalt shingles (about 20"x15") nailed down to 3/4" OSB on 24" spaced 2"x6" rafters.