installing roof vent

[flooded01]

I am almost at the point of sheeting my roof and need to know how to seal the roof vent. In looking at other rv's they seem to use some type of putty on between the roof sheeting and and the roof vent flange what is this? Plumbers putty? and then just silicon the screw heads on the flange screws thanks for any imput. Jay

[asianflava]

My Fantastic Fan came with a close cell foam to be used as a gasket around the flange. What you may be seeing may be some sort of caulking tape. The guys I bought my windows from, sold me a roll to use.

[toypusher]

I just used a bead of polyurethene caulk and trimmed the excess when it dried.

[BILLYL]

I just installed the vent. What I did was got a intall kit from my local RV shop (cost about $6). It was the caulk tape and screws. Clean the top of the roof where the vent will go (you want any grease and stuff like that removed). Place your vent in the opening and square it up. Take it out and lay down strips of the caulk tape. Put the vent back and press it into the caulk. But screws into the 4 corners to square it up and then start scewing it in. When done I covered the screw heads with some silicone.

Clean up and have a glass of your favorite beverage.

Bill

[48Rob]

Hello Jay,

This is part of a piece I did for a different vintage trailer board, but it holds true for new teardrops as well.

Rob

The method I prefer is as follows;

Clean all surfaces well (acetone does a great job) apply warm putty tape in warm weather, leaving a 1/4" or so of excess at the outside edges.

Screw the vent down, then go have lunch, or otherwise wait a while (in warm weather, a couple hours) this allows the putty time to conform.

Then trim off the excess.

Remove a couple screws at a time, inject the sealant of choice into the hole, and reinstall the screws, you don't need a huge amount, just enough to seal the threads and form a "washer" under the screw head.

Come back the next day, and trim the putty tape again, this time undercutting it a bit.
You’ll notice, especially in warm weather, when you come back the second day, that the carefully trimmed putty doesn’t look no neat and clean anymore…this is because the putty has continued to “squeeze out”.

Many otherwise good sealing jobs are ruined by applying the secondary calk layer too soon, or too thin.


The idea is to create a recess for the sealant you'll apply next (a paper thin layer of calk will quickly fail).
The sealant (silicone, polyurethane, or other good calk) serves two functions, the first is to seal the exposed surface of the putty tape (if it isn't exposed to air, it won't dry out, if it doesn't dry out, it will remain pliable and retain the original seal) the second is to provide a "just in case" barrier.

As a side note; though calk will generally “stick” to the surfaces it is applied to, simply laying on a bead, and walking away won’t work very well.
After applying the bead, it must be tooled, or worked.
A little pressure to make sure you have maximum contact is the key.

If in doubt, lay two beads side by side on a piece of scrap, work one in, and leave the other, after they dry, see which one you can easily pull off the scrap…

This may seem a bit much for just sealing a "simple" roof vent, but have a look at the way they seal a new RV.

The majority, due to the time constraints of assembly line procedures (or lack of concern??) have a layer of putty tape installed, trimmed, and then are pushed out the door.

Not much wonder that 90 percent of new RV's sustain water damage within a few years...


Rob

[Gerdo]

I also used RV putty tape. It is great stuff. My fantastic fan also came with a closed cell foam but I ditched it and want for the Putty Tape. I think it cost about $6 a roll at an RV shop. I like the fact that it will stay pliable for years and it is stickey. If I need to remove it it will come off also. I did the same as 48rob and screwed it down, waited, tightened all the screws alittle more. Thats a great idea to take the screws out one at a time and put a dab of silicone under.

[Boodro]

Just what I did. When I laid the buytul tape down , I covered the screw holes with it & still had enough to trim on the edges. Then when I screwed it down , the screws went thru the putty & sealed the holes. saved a few steps that way. I used self leveling caulk on all the screw heads to seal them as well.
Just my 2 sense , ain't worth much!

[flooded01]

Thanks for all the responses. Now maybe I will be able to sleep in the tear when it is done without taking a shower at the same time Thanks, Jay

[cracker39]

I believe that the closed cell gasket is meant to be used on the inside between the garnish and the ceiling. When I ordered mine, I asked Scott about sealing the vent and he recommended using Poly sealant. He said the putty would need to be replaced in a few years. The poly sealant that I bought is advertised to have a life of 50 years.