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Re-sealing Skylight And Roof Seams

12 posts in this topic

I am in the process of changing skylight over shower.

I want to know if there is any reason I can't use 100% silicone sealant to seal around skylight and roof seams instead of the self leveling roof sealant usually used.

Our motorhome is class A 43ft with fiberglass roof.

I could be wrong but it seems like the silicone would last much longer.

Please any suggestions will be helpful.

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I lean towards Dicor!

It tends to be more flexible over a wider temperature range.

The roof being made of fiberglass, silicon will not react or be detrimental. However, fiberglass has a broad expansion and contraction factor regarding temperature changes and Dicor has greater flexibility over a longer period of time.

Dicor will take around 7 to 10 days to begin to firm up, but you can use the coach. Just remember to not to poke at it for a good month, much longer curing time then silicon.

Hope these thoughts help.

Rich.

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Everyone is likely to have an opinion. My opinion is that if silicone caulk was better (especially considering it's cheaper) every RV manufacturer would be using it. I think Dicor is the right path to take but what do I know, I have only installed a couple thousand satellite antennas using this product.

Many people use silicone successfully so I doubt you would have any issues with this product but one thing you have to be aware of is that silicone and lap sealants are not compatible AT ALL. If there is lap sealant there now you will have to clean, clean, clean the surface until there is no residual.

These 2 products will not stick to each other!

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The big secret to getting silicone or any other product to stick is IT MUST BE CLEAN. Use scotch brite and clean with acetone. I have installed things I can’t tell you about to the inside of a F-35 canopy and they stuck.

Bill

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I would use butyl tape as a caulk between the skylight and the roof and then seal it with Dicor lap seal.

This is very flexible and is easier to remove if required in the future.

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I am a little unhappy with the sealing tape, after two years I find it peeling somewhat like bad duct tape does. ALso the Dicor self leveling sealant is cracking. I am sure extreme heat is doing it and am also researching the silicone caulk. Currently do not know if it is compatible with our "rubber roof". I use it on everything else, sealed door on pickup 10 years ago rather than buying new door gasket and it is still good. Used it on horse trailer, which later was sand blasted and came home still in tact, had to scrub it off before repainting. One very good Walmart product ..

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I just sealed bathroom sky light and fantastic fan and 2 other vents . Used dicor 501LSW (self leveling) great product.

I, like Wildebill308 have used much silicone on many aircraft from SR71 to C130. Silicone is great for a lot of applications for what your doing the dicor is better. Lays down very nicely, holds better, looks better, is made for this job. Agree with Wildebill308 clean it very very well. You can use scotch bright and mineral spirits as per the directions. Also watch you tube videos. I also just laid 80 ft. Of 501 dicor on both sides of 40ft. coach, edges of roof to coach seal (fiberglass roof). Turned out good. The you tube videos will convince you.

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I guess I will be trying the dicore 501LSW to seal my recently leaking sky light over the shower...Hmm SR71 to a C130. I did not need any as a f4 Phantom engine guy on the GE J79 engine best in the World turbojet engine,

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Thanks for all the suggestions. I am a newbie that just purchased a 2003 Travel Supreme Class A. I was wondering if anyone has any experience using a product called "Liquid Rubber Sealant". It can be purchased at Home Depot or Lowe's. I used it on the roof of my horse trailer and it worked great on all the seams. It's flexible, can be sprayed on in whatever thickness you want. It is basically a rubber sealant in an aerosol can. Thanks for any feedback on this.

Dan Marlowe

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Hi Danny,

Welcome to FMCA !

The problem with many of the sealants is that they react in a negative way the the EPDM roof material. Just sealing the area with something not made for the roof material could get you into a situation that would require replacing the entire roof membrane.

Nothing with any petroleum based material can be safely used on the material including soaps or cleaning agents.

Rich.

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Personally I have found that using Eternabond Tape solves roof seal issues permanently. Applied properly, you will not have to reseal later. If you use the 6 inch wide tape, it can be put right over the old lap sealant without removal.

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