roof leaking around vents

[astegall1978]

I have a 16x80 metal on metal, I coated the roof a while back and I have to do it again this fall. And the last time I did it I had to replace the flashing part around the plumbing pipe. I went off what a guy at Lowes said to do. I got a plastic one from lowes and removed the old one and silicone all under it and around it and screwed the screws that has the weather resistant washers on them to secure it to the roof and then painted cool seal on it and around it. Well it worked work a little while. Since then I had sprayed flex seal to stop the water from leaking in. My question is do I replace the vent cover and do something different or remove the screws (cause they stick up a little ) and replace them with something like a flat head and then coat it with a layer of the solarflex roof coating then reinforcing fabric on that and then another coat on top of that?

Thanks
Allen S

[JD]

I would replace the plastic vent cap for a metal one like the picture below. It is possible that you cracked the plastic one when trying to get the rubber grommet screws tightened down tight enough to seal. If feasible, remove all sealants around the vent to the original metal and clean well with lacquer thinner. If you have a heavy build up of sealants (shame on you) be sure that the sealant is adhered well and is not cracked or peeling. You can grind down a layer or two with wire brush on a drill or grinder. Be sure to lacquer thinner wash off the top and bottom of the screw flange of the metal vent, for there will be a film of manufacturer's oil on it.

Then as your home store guy said, heavy sealant under the flange, screw the cap to the roof letting the sealant ooze out the sides and through the screw holes. Then seal the top of the flange, where the screws are, and the little top nut, to keep it from loosening. I would not use silicone anywhere on a mobile home except as a bathroom caulk. Even there, there are better caulks. I would use a polyurethane roof flashing sealant. Tremco Vulkem 116 is my non-pretty sealant of choice for most things, especially roofs.

Hope this helps.

[thatswhoiam]

after you do what jd says to do, you can get some peel and seal to further secure the vent to the roof. I used this on a vent pipe that was leaking , with cracks all around the flashing of the vent. it was a mess, of course i should have replaced it properly, but i didnt, and i just sealed it up with the peel and seal. i covered it starting at the base and went all the way about halfway up the pipe in a upward circling pattern .with about 7 or 8 pieces that were about 10 inches long each. this was about 3 years ago and its still holding. sidenote: ....i wouldn't want to be the one to have to pull all of that stuff up, because once it sticks, its on there for the duration. you just have to make sure that the surface is really dry, and clean. you can put it on top of other sealants (get rid of any silicone tho , nothing sticks to that as far as i know) , but try to sand the surface as well as you can. or you can apply something like spirits to dry it out , or what i did was brush some oatey pipe sealant...or 3m adhesive spray (let all of these dry before putting tape down). and also , make sure the tape (peel and seal) is very warm before you apply it. i cut the strips and laid them on the hot roof for several minutes (with backing still on tape). makes the tape very pliable and easy to work with.