I need to run a hood vent through the roof. Ive seen people nail the bottom edge of the vent flange on top of shingles through the roof deck. That seems like a potential leek. Also, when I slip the vent under the shingles (top and Sides), should I tar under the shingles top and/ or sides? Thanks, bobby
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I usually run a bead of caulk under the front flange of vents, but never nail where the nails would be exposed. The only place where face nailing on any traditional roofing product that I know of is necessary is the last ridge cap youy install.
gl
I'm not sure I want popular opinion on my side -- I've noticed those with the most opinions often have the fewest facts. Bethania McKenstry
I just went throught this with the mechanical inspector: here it is legal to vent into attic air. He claimed that attic air was not classified as living area air. As long as the pipe exit above the insulation. So since I have a new metal roof I ran my hood vent and fart fans pipe to inches from the ridge vent but not exit through roof. Now sewer gas must exit roof, different inspector, different department.
"here it is legal to vent into attic air."
Where is "here?"
Besides being stupid to vent bath and kitchen fans into the attic, it's potentially dangerous if the stove is a gas stove, or if it leads to mold growth.
Even if you're in a temperate area, you can easily get significant amounts of condensation in an attic if you dump that moisture upo there.
Is your mechanical inspector named Gump, by any chance?
Look guys, don't jump on me. The mechanical inspector says its legal to vent into attic air, thats all.. i do not remember telling the whole world you must vent into attic. I did it , because of my new metal roof that I did not want to leak. Also if you re read the post you will notice it vents couple inches below the ridge vent. so it not like I filling the attice space with moisture. Hey dont kill the messager just because you do not like the message. Check your codes in your area it might be legal there too.
In BROWNBAGG's defense I must say that I have heard much the same from some inspectors in Florida. Little danger of excessive condensation. In this case it was allowed only for bathroom exhaust fans. It was strongly suggested, another inspector demanded, that the flexible exhaust duct stops near a vent, soffit, trough or ridge. Kitchen exhaust and gas appliances in all cases must still be vented to daylight through an approved duct for obvious reasons.
Brownbag,
Sorry if it seemed like I was jumping on you, I was aiming for the mechanical inspector who said: here it is legal to vent into attic air. He claimed that attic air was not classified as living area air. As long as the pipe exit above the insulation.
Terminate it by the ridge vent or a thru roof vent, no problem, but just anywhere above the insulationisn't good enough.
I should have made that clearer, I quess
Grant,
What about the sides and is the front the top or bottom? Thanks, for the AD.
The front is the bottom (I tend to talk about it as I can see from the ground. Nail the sides as is necessary to get the flashing to lay right. The sides will be covered by the shingles.
gl
Only the mediocre are always at their best. Jean Giraudoux
Do not nail into an exposed flashing, you are correct, a leak will be the result. Do not go crazy on the tar or Butyl rubber, as too much can be a problem, and it does not take a lot to do the job, a 1/4" bead should do the trick, if the flashing is all metal. If you have any rubber in the flashing, be warned that tar will eventually eat into it, and the rubber, if it is seated down correctly should seal things nicely for a long time. If your vent is large enough, then slip in some step flashing attached or glued high as you can. I am not sure who the person is that suggested attic venting, but I would not do it, as it will surely lead to problems. If you are free venting a stove vent up into an attic space, I would wonder about spark or flash suppression, as an attic is filled with all kinds of flammable materials. (Though if your cooking is producing sparks or flashes, perhaps you should rethink your profession or hobby?)
-Jay