Replacing 9" roof vent in Bigfoot 17

[Michael Collins]

Hello again. I've purchased a new roof vent for our 1988 Bigfoot 17. It's a Hengs 9x9 which is an oddball size that Bigfoot used in the bathroom. I couldn't find just the cover, so I need to remove the old vent, and install the new one. I have new butyl tape and dicor roof sealant ready to go. Will the screws still bight into the fiberglass when I install the new vent? Any tricks? How tight do you go- should the butyl squeeze out the sides? Thanks for the help. I might try to get this done later today.


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[tractors1]

You'll know more by pulling one screw first. MOST (dunno about BFoot) builders secure a wood frame inside the shell for mounting things through the roof. If your screw is 1/2-3/4 inch long you should be fine.

[Michael Collins]

I had a boler before this Bigfoot and I know you had the build a wooden frame because there was little to no insulation in the roof leading to an overall thickness of 1/2". Bigfoots appear to have a 1.5" thickness due to styrofoam insulation. If I had a wooden frame under the vent on the inside, I'll need 2" screws. I know this would be the most bombproof method. I'm just wondering what others have done.


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[Gilles]

Hi Michael, I have not had to replace the wind 9 X 9 but I made the installation of a Maxxair, maybe that explanations will be useful.

I used the aluminum supports 90 °, I have flattened horizontally and then fix the framing 9 ".
You can see in my "Registry", "Renovations" : Gilles's Trailer :: 1986 Bigfoot 15B17G

Have a good day,

[Michael Collins]

Gilles, I tried your link with no success. I took off the aluminum trim from inside the bathroom and found a 1.5" piece of wood surrounding the vent. There is a lot of meat for the screws to bight into. So did you replace your 14" vent with a maxair? I'd like to look at your install because we might do the same one day.


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[tractors1]

Originally Posted by Michael Collins

Gilles, I tried your link with no success. I took off the aluminum trim from inside the bathroom and found a 1.5" piece of wood surrounding the vent. There is a lot of meat for the screws to bight into. So did you replace your 14" vent with a maxair? I'd like to look at your install because we might do the same one day.


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Helped a friend do this - we measured back from the old framing to create a 14x14 opening, then used firring strips 3/4 x 1 1/2 stuck to the underside of the roof with VHB tape to hold them in place while we did the roof side install of a Maxx Fan so we could screw into the wood for compressing the butyl tape topside. The garnish ring slid up from inside the rig; think we had to trim about an inch off the garnish ring so it fit all the way up inside the fan. Check Youtube for videos and the Maxx Air website for installation procedures.

[Gilles]

I have not yet replaced by a 14 ", I simply covered the 9" by Maxxair order to let the wind 9 "opened at any time, without danger of rain inside.







At our annual meeting of shells, in September, I met one who had added a 14 "but in the back of the air conditioner. He said that there were already aware of who was going to where he installed 14 "Fantastic, in and out.

May be in a futur time...

[Jack L]

Here is an idea for you to think about DISCLAMER I've never done this myself.


The fiberglass roof on my Bigfoot has the foam underneath it so getting a wood strip between the foam and the fiberglass would involve removing some foam but I think it would be much easier to insert a thin strip of aluminum between the fiberglass and foam. This would give the self tapping screws something to grab that would be much stronger than the fiberglass by itself. Hope this helps.

[Gilles]

Originally Posted by Michael Collins

Gilles, I tried your link with no success. I took off the aluminum trim from inside the bathroom and found a 1.5" piece of wood surrounding the vent. There is a lot of meat for the screws to bight into. So did you replace your 14" vent with a maxair? I'd like to look at your install because we might do the same one day.


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I have not changed, I simply added a Maxxair on vent 9 ", without having to add new holes in the fiber.
I believe that a vent of 14 "in the bathroom, will take too much space ...

[Gilles]

Originally Posted by Michael Collins

Gilles, I tried your link with no success. I took off the aluminum trim from inside the bathroom and found a 1.5" piece of wood surrounding the vent. There is a lot of meat for the screws to bight into. So did you replace your 14" vent with a maxair? I'd like to look at your install because we might do the same one day.


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Clic on my name,
View Public Profile appear, clic on,
further down the page You'll see Registry, clic on,
Clic on the Bigfoot pic,
and lower You'll see pic modifications...

[Michael Collins]

Thanks Gilles.


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[Michael Collins]

Job was super simple. I re-used the stock aluminum inside trim because the new plastic trim wasn't deep enough to cover the 1.5 of wood and insulation. Vent came out fine. I replaced the old screws with stainless screws. Sealed with new butyl and a wide bead of dicor lap sealant.


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[tractors1]

Don't you love it when a plan works out? I sure do!