Fixing Windows - Fiberglass RV

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Old 07-07-2009, 03:42 PM   #1
Mike Whitney's Avatar
Trailer: Lil Bigfoot
Posts: 89
Hello -

I've been reading a lot here about re-sealing windows, and avoiding silicon.

I called a local shop (actually the same company who made the windows in 87 for our 'new' lilBigfoot) and they said they could re-glaze and reseal all windows for 60-90 dollars max plus supplies. I hadn't considered re-glazing, and I'm not sure if this is a good thing to do. This price is with me taking the windows out and bringing them in relatively clean - no problem. I want to remove them anyway and reseal between the flange and the exterior body of the trailer.

I've read here that butyl tape is the best to use. While I've never used it, I imagine it to be a stick sealant that adheres to both sides. The window place said that they have 'foam tape' that is less messy than butyl tape and would work as well. The also said that at the factory, they would have used butyl tape and then applied 'a secondary seal of silicon once the window was screwed in'. I assume they mean around the perimeter of the window frame, but I thought the general consensus was to avoid this...

Has anyone uploaded images of the process? Any suggestions are appreciated!


We have some foam tape available for re-installing which is far less messy
than butyl, especially if you plan to paint at a later date. You may still
want to install a perimeter seal around the window, there's some neutral
cure silicone products that are paint compatible.


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Old 07-07-2009, 10:20 PM   #2
Doug P.'s Avatar
Name: Doug
Trailer: Escape 5.0TA
Southern Alberta
Posts: 72
Hi Mike

Do not use the foam tape, use only butyl tape.
You just remove the windows, clean up the old putty or butyl tape
apply new butyl tape (it comes in rolls about 1/8" thick and 1" wide)
press the window back in and reinstall the screws.
Some places then apply a capping bead of silicone to the outside
but this will be easy to peel off in a year or two, we never do this in our shop.
The nice thing about butyl tape is that every time it gets hot it reseals itself.
Reglazing is not normally needed.


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Old 07-07-2009, 10:30 PM   #3
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Donna D.'s Avatar
Name: Donna D
Trailer: Escape 5.0 TA, 2014
Posts: 25,065
Oh I agree with Doug on this one. I wonder if the local shop you talked to Mike had any experience with molded fiberglass trailers? Blobbing on silicone or some other sealer on the outside of the window is not a fix. Butyl applied properly seals the frame of the window to the body... no need to glob on something around the edge.

I wonder how they "reglaze" the windows? The original Hehr windows in my 1988 don't leak. Granted I've pulled and replaced the butyl for between the frame and the body of the trailer, but the windows themselves are fine. At this point the only way to get the glass out and "reglaze" is to break the glass. (Which I've done in the door window... for a different reason than "reglazing.")

Hummmm interesting topic....
Donna D.
Ten Forward - 2014 Escape 5.0 TA
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Old 07-07-2009, 10:34 PM   #4
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Booker B.'s Avatar
Name: Booker
Trailer: Trillium
British Columbia
Posts: 983
Here is a member showing how to very cleanly install a fixture using butyl tape:

Butyl Tape, Silicone and sealing, Split topic

Nothing I have butyl taped has looked this good <_<
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Old 07-08-2009, 04:58 AM   #5
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Trailer: 1984 U-Haul 13 ft
Upstate New York (near Albany)
Posts: 108

When I bought my U-Haul, I had it painted & the windows resealed(or so I thought they were resealed). Took the trailer camping. Rained the first night. All the rain poured in the windows. Took it back-all this guy did was glob more silicone on the windows. This spring, I brought it to a small rv place & insisted on reinstalling the windows with butyl or otherwise I would not pay him unless butyl was used. One window has a minor leak(emergency window) that I can deal with.

Moral of story, use butyl tape.
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Old 07-08-2009, 01:01 PM   #6
Mike Whitney's Avatar
Trailer: Lil Bigfoot
Posts: 89
Thank you all for your comments. The general thinking seems to be: Butyl Tape good , silicon and foam tape bad .

I talked with Con and Raya as well and have a step-by-step method that I've extracted from their emails just in case this helps others. I'm so glad I found this resource. I own a honda 750 spirit and am a member of another forum. I have to say, it's refreshing to have people be so friendly and accommodating (and not boo you off the stage if you've asked something that's been covered). Simply put, this is a great forum, great advice and great people. Glad to be a member here.

My interpretation from the help Con, Raya and others here:

1) remove windows and then clean all 'silicon' or caulking from trailer and windows with an acrylic scraper
2) clean area with a solvent (white gas/naptha/methyl hydrate or the like)
3) dry fit the window and mask perimeter of trailer next to window with 3m or green/blue painter tape
4) use butyl tape app. the same width of the window flange and stick the tape to the window
5) put window in and attach trim ring on inside
6) tighten trim ring (working as you would when tightening lug nuts in a cross pattern
7) allow butyl tape to ooze out and scrape off excess or allow to spill out on to green/blue tape
8) let sit for a few days as the butyl will continue to 'bleed' - repeat and clean with a solvent.

I've read also that when you take the window out, you can cover the gap between the inside and outside walls (space where insulation would be) with aluminum tape. Should any water get past the butyl tape, it will not go inside the wall, but rather, show up in a more obvious spot. This makes sense to me, but perhaps there is another opinion on this.

When I get to doing it, I'll log my progress in case I can help anyone out.


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Old 07-08-2009, 04:06 PM   #7
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Name: Roger
Trailer: 2009 Trillium 1300 "Homelet"/2014 Subaru Outback "Rosie"
Posts: 2,208

Last week I was talking to Tom Young on this. He said do not use silicone because it will crack and then you can pull the whole thing off like a string. He reccommends acrylic sealer which is what he uses on the new Trilliums. I found that you have to be careful not to wipe it onto the surface or it picks up dirt and looks bad. Tom says acetone will take it right off. Acetone = nail polish remover. I might try o-ring cord. Since it is round, o-ring will compress better than tape. Just be sure to get it on the outside of any bolt holes and put the seam on the bottom.


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