Shower skylight leak!

[MSHappyCampers]

I've got a REALLY weird problem!  I've been fighting a roof water leak in the bathroom for a long time now, and thought I had solved the problem!  WRONG!  I had a bad leak around the Fantastic fan opening.  After re-sealing it I pulled out the ruined vinyl ceiling to expose a lot of rotted wood.  At that time I discovered there was water collected in the air space between the inner and outer layers of the shower skylight.  I drilled holes to let the water out, then sealed the holes with clear silicone.  

I have been spraying the wood ceiling for mold after removing the vinyl and before replacing the vinyl.  Yesterday we had a huge rain that I knew would be a good test of my repairs.  I inspected the ceiling yesterday afternoon and there were no signs of water on the wood.  Then I looked at the skylight again!  It again had a large amount of water between the layers!  I can't imagine how it's getting in there!  I resealed the skylight a couple of months ago with EternaBond tape, caulk, and a coat of liquid rubber.  

Does anyone have any idea how this water is getting into the skylight?  I really appreciate any advice you can offer!  🙂

Joe

[Frank Bergamo]

Joe,

possibly a crack in top layer of skylight. If water stayed in between layers, then top layer must be leaking. Hope this helps.

[MSHappyCampers]

23 minutes ago, Frank Bergamo said:

Joe,

possibly a crack in top layer of skylight. If water stayed in between layers, then top layer must be leaking. Hope this helps.

I've inspected it closely many times and can't see anything!  Very frustrating!  

[DavidL]

Use a garden hose and start from the lowest level and water.  Slowly (across many minutes) higher until you see water accumulation where it doesn't belong.  Walla...you found your leak.

 

[MSHappyCampers]

6 minutes ago, DavidL said:

Use a garden hose and start from the lowest level and water.  Slowly (across many minutes) higher until you see water accumulation where it doesn't belong.  Walla...you found your leak.

 

You can't see above the wood ceiling to know where the water is getting through the roof.  

[DavidL]

I thought the water was appearing in the skylight (which is higher than the ceiling)?  The water isn't going to rise above the crack (unless pressurized water pushes water in).

Edited October 30, 2020 by DavidL

[MSHappyCampers]

4 minutes ago, DavidL said:

I thought the water was appearing in the skylight (which is higher than the ceiling)?  The water isn't going to rise above the crack (unless pressurized water pushes ater in).

I misunderstood what you were saying, that is, to use a hose on the skylight, right?  I thought you were talking about the roof area.  Sorry 'bout that!  🙂

Joe

[Pampero]

Can you create smoke somehow?

When I had my auto repair shop I had a smoke generator to diagnos emmission leaks on some systems on the cars, and many times I use it to find water leaks. Maybe a steamer will do. Someone from inside creating steam with one of those clothe steamers or you can make one of this: 

 

[vito.a]

RV skylights should be sealed with non-petroleum sealant.  Petroleum will cause the skylight to crack and leak.  

SUREBOND BriRus SB140 Skylight Sealant (SB-140 T White)

[RNMCBR]

I had a similar problem. Not until I pulled the inner dome out did I see the cracks in the outer dome from the inside looking out. I could not see them from the outside. That was my leak.

[Bob Nodine]

Joe, sounds like it is time to remove the skylight and replace it.

 

[96 EVO]

Yeah, mine had been sealed over with Dicor self leveling. When I removed it the corners were all cracked.

Replaced the outer dome, and used a thick bead of Surebond SB140 under the flange, then a strip of Eternabond over.

[MSHappyCampers]

I'm gonna get back up there today and look at it again for cracks.  It's hard to believe it could get that much water in between the layers with a crack that hard to see!  Anybody have a part number for the outer dome and where did you find it?  How is the outer dome attached?  Thanks for all your help!

Joe

[RNMCBR]

I got mine off Amazon. I found the cracks right before leaving for Quartzsite so I needed it in a hurry.

[vanwill52]

There have been quite a few instances of cracked outer and/or inner skylight material due to using the wrong sealant.  That happened to me before I learned that non-approved sealants would cause cracks.

But ALL the skylights are simply too thin to be adequately sealed by screws alone, even when the screw spacing is quite close.  On both my Dynasty's, I TIG-welded TWO aluminum frames about 2" wide and the shape of the outside of the skylight.  One was 3/16" thick, the other was 1/8' thick.  The 1/8" thick frame got screwed to the coach roof with the correct sealant under it.  That one smoothed out the roof imperfections and gave a smooth, hard surface for the skylight plastic to sit on.  I sandwiched the inner and outer skylights between the two aluminum frames with screws about 1-1/2" apart and the correct sealant. 

That was a permanent fix on both my 1993 and 2000 Dynasty's.  For the 2000, I was unable to locate the inner skylight, and used a flat sheet of 1/8 polycarbonate.  On the 2000, that fix is about seven years old now.

[MSHappyCampers]

UPDATE-  FOUND THE PROBLEM!  I got up there today and found a tiny crack between the EternaBond tape and the skylight!  It was so small I would never have thought that any water could get in, but when I pulled up the tape there was water underneath!  While I was working on the sealing I accidently pressed my hand against the plastic dome and it split wide open!  😲

Well, it was 18 years old so I guess it's about time!  I found a replacement on Amazon and ordered it along with the special sealant that vito.a suggested.  I will be finishing the sealing with the EternaBond 4" tape and Dicor 502LSW sealant.  Hopefully when I get this installed and give it a good water test with the next heavy rain, that I can go ahead with the ceiling replacement.  

Thanks to all of you for your comments and suggestions!  👍🙂

Joe

[windsorbill06]

joe,

that sealant that vito recommends is good stuff.  I've used it.  But it takes nearly 3 weeks to fully cure, so be aware.

[MSHappyCampers]

4 minutes ago, windsorbill06 said:

joe,

that sealant that vito recommends is good stuff.  I've used it.  But it takes nearly 3 weeks to fully cure, so be aware.

Thanks for the tip!  🙂

[96 EVO]

1 hour ago, windsorbill06 said:

joe,

that sealant that vito recommends is good stuff.  I've used it.  But it takes nearly 3 weeks to fully cure, so be aware.

I'm not sure it ever 'cures', Bill.

If it was Surebond they used at the factory (and it looks like it was), when I lifted mine after 10 or 11 yrs, it was still very soft, and easy to scrape off.