skylight condensation

[lawrosa]

Living in my 26ft coachmen for the past 6 months now. Im in Myrtle beach.

Just noticed water droplets on membrane between ceiling and skylight bubble.

its colder here and running electric heat past several weeks.

Noticed it last week too and little plastic membrane that is sticky tapped to ceiling besel was unattached on one side. ( Possibly shower steam made sticky tape non sticky)

I pulled besel down and whole bubble was wet with large droplets. roof membrane folded over so drops were collecting in ceiling collar. No damage except small edge of luan damp.

Upon removal I see the back roof truss is open and I can see back wall of camper. Slight dew on nails and wall membrane on back wall.

I would think the heat from in the camper it getting through they membrane and interacting with the cold air in the bubble skylight and condensating..

Im thinking to insulate all gaps and openings around roof trusses with collar removed. Then put that membrane back but seal it to the collar with silicone.

Is that my best bet?

I could of course leave the membrane off too. as this is how I have it now so I can watch it a few days until I get some insulation.

Possibly spray foam may be better but I probably will just get a bag of the soft stuff.

So is my plan feasible? Anyone have this issue?

[westend]

DEfinitely insulate the void in the ceiling. You can probably get some thin batt insulation at a big box store. That can be pushed into the void with sticks or wire. If you source 3 1/2 batt insulation, that can be divided into thinner pieces. Wear gloves.

Basically, you have a condensation point at the skylight. It is an indication of the humidity being too high. Venting is the best solution. You can also insulate underneath the sky light but you'll lose light and the insulation must be sealed totally. Otherwise, you'll have condensation again on the inside of the skylight. You could choose to seal the skylight opening with a transparent material like acrylic. Again, sealing all areas is necessary to eliminate condensation on the skylight.

[Huntindog]

You MUST lower the humidity inside. Water on windows, skylights etc. is a warning sign. The same thing is happening inside your walls, just slower because of the insulation. If this is a filon walled TT or similar, delamination will be the result if you do not address the issue.... And just worrying about the skylight is NOT gonna fix the underlying issue.

If you have your TTs manual.... Read what it has to say about this.

You are on your way to ruining your TT at present....

And yes, many of us here have dealt with condensation in cold weather.

I use a 40 pint dehumidifier, or leave my vents and windows cracked, depending on how cold it is.

[lawrosa]

mobeewan wrote:
If everything is sealed properly and you have no leaks then there should be no moisture between the skylight bubble and the interior skylight bezel.

I found water was dripping from my bezel flange and that there was moisture between the bezel and the bubble. When I removed the bezel I found the skylight wood framing had damp spots and water had been weeping under the ceiling panels. Upon further examination I wound up putting my thumb through a water damaged spot in the ceiling paneling. The ceiling insulation was wet and trusses had damp and water stained wood. The skylight bubble was cracking around the inside perimeter of the flange and water was leaking through the cracks, running down and wicking onto the top side of the ceiling paneling and spreading out wetting the insulation and rafters. The skylight bubbles eventually suffer the toll of UV damage just like the plastic vent fan hatches and need to be replaced eventually. If your skylight is not cracking and leaking through your caulking on and around the flange may need to be replaced.

Its a brand new camper. There is no damage to the skylight. And no caulking is leaking. The underside of bubble is condensating and running down to the edges..

Amazing that no one had/has this issue.. Maybe no one winter camps.

[mobeewan]

If everything is sealed properly and you have no leaks then there should be no moisture between the skylight bubble and the interior skylight bezel.

I found water was dripping from my bezel flange and that there was moisture between the bezel and the bubble. When I removed the bezel I found the skylight wood framing had damp spots and water had been weeping under the ceiling panels. Upon further examination I wound up putting my thumb through a water damaged spot in the ceiling paneling. The ceiling insulation was wet and trusses had damp and water stained wood. The skylight bubble was cracking around the inside perimeter of the flange and water was leaking through the cracks, running down and wicking onto the top side of the ceiling paneling and spreading out wetting the insulation and rafters. The skylight bubbles eventually suffer the toll of UV damage just like the plastic vent fan hatches and need to be replaced eventually. If your skylight is not cracking and leaking through your caulking on and around the flange may need to be replaced.

[lawrosa]

ill try sealing it like I stated. I was thinking on one of these.But I am alone and using electric heater only.

[ktmrfs]

full time living in cold weather IMHO means you highly likely need a compressor driven dehumidifier. especially if youy aren't running a exhaust fan whenever you shower or cook.

[lawrosa]

I know this is a fan pic. but it shows the wood boxed out around the opening.

Since I have an arched roof i have a gap between the wood and the trusses.

[lawrosa]

Its a bathroom skylight like this

At the top is a plastic film. I removed the plastic film for now. Now I have direct view of the bubble skylight.

Its the bubble that had the condensation on the underside..

Now when I had the bezel removed you can see the roof trusses. Its the roof trusses that have no insulation on one side. So its kind of open like an attic. ( Ill try to find a pic of that.)

[lawrosa]

Ill try to post pics

[pianotuna]

Hi,

If you do use foam get the low expansion type.

What to do about condensation?

The cause of the condensation is the walls are below the dew point temperature. If the walls can be made warm enough the problem disappears. Running a fan to circulate air may help to raise the temperature on the surface of the wall.

One other solution is to reduce the relative humidity inside the RV.

The easiest way to do that is to open a roof vent a bit, find the furthest window from the vent and open that a bit. An electric heater near the window will improve that and keep you warmer. I'd suggest a low wattage radiant type, or a small oil filled (if the oil filled can be on a shelf so the air from the window passes over the fins.)

I know opening a vent and window when it is cold seems counter intuitive, but it does work.

Another possible solution is an electric dehumidifier--but the cooler it is the poorer they work. They are generally energy hogs, some what bulky and definitely noisy.

[enblethen]

Sounds like the skylight is not sealed. You are getting moisture from inside the rig to between panels of skylight.Not sure what your installation is like and how to reseal. There is no where for the moisture to escape to the outside, so it stays.
If this is in bath, you need to get a better exhaust fan so moisture does get into skylight. Fantastic fan
Do you have covers and leave your vents open? If not get covers and leave the vents open at least a couple of inches at all times.

[old_guy]

sounds like you need more insulation in the attic

[Lwiddis]

“No damage except small edge of luan damp.”

You hope but I don’t think so. Time for a complete inspection, repair and sealing. As Don said, lower the humidity.

[lawrosa]

donn0128 wrote:
Lower the humidity inside.

Unfortunately thats not a good answer..Thanks anyway.

I don't have condensation issues anywhere else.

[donn0128]

Lower the humidity inside.