Roof insulation condensation problem

[JohnWedell]

I Noticed a small drip coming from the vent in the bathroom. I took the trim off and noticed that the aluminum foil insulation used in The ceiling is soaking wet. I opened all the access areas in the trailer where the speakers are etc. and found everything had condensation on it and was very wet. Right now it’s 29° outside and inside the trailer it’s 68. This is a big problem. Have no idea what to do.

[RoadrunnerII]

Run the bathroom fan pretty much constantly and buy a dehumidifier. I upgraded to a maxxair variable speed fan. Much quieter and moves way more air when needed. Just normal living inside the trailer creates a lot of moisture. It condensates on the warm to cold surfaces.
Wipe down any moisture off the windows as well. Dual pane windows help a bit. We use reflectix cut to fit windows to reduce the cold and heat infiltration.
Head further south and get out of the cold is the best solution.

YMMV

RoadrunnerII

[CAG]

https://rvshare.com/blog/condensation-in-your-rv/

There are many more articles on the Internet concerning this issue. In most all RV manuals there will be a short comment on condensation and how to prevent it.

[JohnWedell]

Originally Posted by RoadrunnerII

Run the bathroom fan pretty much constantly and buy a dehumidifier. I upgraded to a maxxair variable speed fan. Much quieter and moves way more air when needed. Just normal living inside the trailer creates a lot of moisture. It condensates on the warm to cold surfaces.
Wipe down any moisture off the windows as well. Dual pane windows help a bit. We use reflectix cut to fit windows to reduce the cold and heat infiltration.
Head further south and get out of the cold is the best solution.

YMMV

RoadrunnerII

That is understood. The condensation is not inside the trailer it is above the ceiling and also above the roof insulation where the foil is on top of the insulation up against the roof plywood. I doubt if there’s anyway to stop that condensation. There are no attic vents. The roof is sealed so a dehumidifier will not help. The inside walls and ceiling are completely dry and we use the bathroom vent on high when we take a shower. we have no condensation at all inside maybe a little bit on the aluminum by the windows but that’s it.

[Jagiven]

Moisture vapor likes to condense where ever it is cold (lower dew point). I would try to dry it up really good, then when your ready to close it up, install an aluminum foil duct sealing tape, across the gap between the ceiling and the vent frame, so the vapor cannot get through and condense.

May need a fan and a dehumidifier to dry it up first.

https://www.amazon.com/s?k=metal+duc...b_sb_ss_i_1_10

[CAG]

Just a thought but have you checked all seals around vents and pipes on the roof? Moisture has to be getting in there somehow.

[JohnWedell]

it may not be understood, the entire underside of the roof has condensation on the aluminum foil not the ceiling not inside the camper when the dewpoint gets below a certain temperature water condensers on it it’s aluminum it’s metal that’s the problem. I think the foil they use is a problem.

[Jagiven]

Originally Posted by JohnWedell

it may not be understood, the entire underside of the roof has condensation on the aluminum foil not the ceiling not inside the camper when the dewpoint gets below a certain temperature water condensers on it it’s aluminum it’s metal that’s the problem. I think the foil they use is a problem.

The foil is acting as a vapor barrier, and sounds like it is keeping the ceiling board from getting wet and being damaged. The root issue probably is Jayco did not seal around the gaps.

The vapor has to have some route to get into the "attic space" I suspect it is getting up their through the hole that was cut in the ceiling for the roof vent and the skylight. This cut was made oversize which made a small small gap, between the vent/skylight and ceiling board. The bathroom makes the most sense as there is a lot of water vapor naturally in that area. Get it dry and apply a sealant (aka AL tape) to keep future moisture from migrating up into the attic space. Good chance there are big gaps around the sewer vent pipes too. But they will be harder to address.

[CAG]

One topic not directly related to this is one where owners have an issue with odors when running various fans in the rig. What some have found is that the area around roof vents from the black and gray tanks is not properly sealed and odors are sucked from those gaps back into the living area. Sealing the area around the vents on the roof stops the odors.

With that thought in mind, came my question about checking those vents on the roof. If that area is no properly sealed moist air could be getting back into the space between the roof and ceiling.

Just a thought but if everything else fails I would be checking that too.

[Sundancer330]

Originally Posted by JohnWedell

it may not be understood, the entire underside of the roof has condensation on the aluminum foil not the ceiling not inside the camper when the dewpoint gets below a certain temperature water condensers on it it’s aluminum it’s metal that’s the problem. I think the foil they use is a problem.

The only way to fix this problem is add some vents to the roof, the moisture is trapped and the heat from inside the TT causes it to condensate. Older homes used to do this before they came up with a formula as to how many sq inches of venting is required to stop this problem. Many older homes the roof decking got so moldy and rotted it had to be replaced.

[Jagiven]

Originally Posted by Sundancer330

The only way to fix this problem is add some vents to the roof, the moisture is trapped and the heat from inside the TT causes it to condensate. Older homes used to do this before they came up with a formula as to how many sq inches of venting is required to stop this problem. Many older homes the roof decking got so moldy and rotted it had to be replaced.

With the TT, in cooler weather, we always leave the roof vent cracked open and our bunk windows, so the moisture has an easy way to escape. Since I installed my vent covers, I have never fully closed my roof vents. They are open at least 1/2". Ever since, I have never noticed any condensation build up within our HTT. I have to admit, I have never looked above the ceiling in the attic space.

[JohnWedell]

Originally Posted by Jagiven

With the TT, in cooler weather, we always leave the roof vent cracked open and our bunk windows, so the moisture has an easy way to escape. Since I installed my vent covers, I have never fully closed my roof vents. They are open at least 1/2". Ever since, I have never noticed any condensation build up within our HTT. I have to admit, I have never looked above the ceiling in the attic space.

If you’re using it in cold weather I suggest you remove a speaker and feel above the insulation where the foil is just below the roof plywood you may be shocked

[xrpb11a]

So how does one check "the entire underside of the roof"??
Remove the complete interior ceiling, and whatever else is between that and the underside of the roof?

Originally Posted by JohnWedell

it may not be understood, the entire underside of the roof has condensation on the aluminum foil not the ceiling not inside the camper when the dewpoint gets below a certain temperature water condensers on it it’s aluminum it’s metal that’s the problem. I think the foil they use is a problem.

[JohnWedell]

Originally Posted by xrpb11a

So how does one check "the entire underside of the roof"??
Remove the complete interior ceiling, and whatever else is between that and the underside of the roof?

No. I removed the speakers in the living room the vent in the bathroom and the speakers in the bedroom it’s all wet what would you summize. I guess the insults are starting

[RoadrunnerII]

I would suggest running bathroom fan 24/7.Moisture is migrating through ceiling insulation up to the bottom side of the roof decking. Its condensating on the cold surface. You need to change the inside air more to reduce the moisture level. Running fan only after a shower is not enough. Our stick and brick is a super tight build. We have an air to air exchanger in the house to remove the excess moisture. It works pretty well.

RoadrunnerII

[Screwby]

When using our camper in the winter we had moisture/frost issues everywhere. I’m not shocked at all that you found moisture where you did. We had moisture/frost inside any cabinet that was on an outside wall (we had to leave them cracked open to increase airflow to mitigate). We had moisture in the upper corners of the slides especially the closet area where the airflow was restricted. Frost and moisture was a constant on all of the windows so we eventually just covered them with reflectix anyways.
Even though our camper did extremely well in the cold winters for the last two years we still had our issues. Anywhere there was the warm air and moisture we were creating from heating, breathing and cooking it created condensation in nooks and crannys where airflow was minimal and cold surfaces existed. We stopped a large majority of the problem by using a nice big dehumidifier and running fans to keep air moving. It was a huge difference and the lesson was learned. We can camp in sub zero temps but even with a four season camper there are steps to be taken to minimize moisture problems.

[Rustic Eagle]

I winter in the Texas Hill Country where temps (20-78 degrees) and humidity (30% - 90%) are all over the map, thus condensation can be a real pain. I did the following and has eliminated 90% of my interior and attic condensation issues.........

I removed my interior kitchen & bath skylight frames, bath exhaust fan frame, main A/C ceiling cover, and A/C ceiling directional vents. Using foil insulation, reflectix tape, and a staple gun, I blocked off all openings to the attic....., and there were plenty. The only areas I didn't address were the ceiling mounted speakers.

Also, I purchased a Ivation 13-Pint Small-Area Desiccant Dehumidifier..., IMO a must for controlling interior moisture, and keeping it from transferring into the attic. I use the bath/stove exhaust fans when required.

Bob

ps: With the A/C directional vents removed this would be a good time to confirm that the circular vent collars don't interfere with A/C flow within the main duct (trim collar if required).

[JohnWedell]

Originally Posted by Rustic Eagle

I winter in the Texas Hill Country where temps (20-78 degrees) and humidity (30% - 90%) are all over the map, thus condensation can be a real pain. I did the following and has eliminated 90% of my interior and attic condensation issues.........

I removed my interior kitchen & bath skylight frames, bath exhaust fan frame, main A/C ceiling cover, and A/C ceiling directional vents. Using foil insulation, reflectix tape, and a staple gun, I blocked off all openings to the attic....., and there were plenty. The only areas I didn't address were the ceiling mounted speakers.

Also, I purchased a Ivation 13-Pint Small-Area Desiccant Dehumidifier..., IMO a must for controlling interior moisture, and keeping it from transferring into the attic. I use the bath/stove exhaust fans when required.

Bob

ps: With the A/C directional vents removed this would be a good time to confirm that the circular vent collars don't interfere with A/C flow within the main duct (trim collar if required).

The living area of the trailer is extremely dry in fact right now it’s 29° outside and there is no condensation on the aluminum on the windows. We rarely do any cooking and when we shower we open the bathroom vent up with the fan on high and there is no condensation. there isn’t any fog on the mirror. The only problem I’m having is in the attic area with the foil insulation up against the plywood roof. for some reason I think I’m getting condensation from the difference in temperature from outside to inside. I sent an email to Jayco but I doubt they will get back to me on it. I’m thinking about putting in mushroom type attic vents hoping that might solve the problem or at least help. I’m really worried about roof rot or mold.

[goducks]

This is probably more common than RV owners want to know. There's really nothing you can do about it. Poor construction methods are to blame. Or actually a poor design.
No attic space to vent excess moisture. Unlike a house where you have an attic with vents. there's no way to properly vent an RV roof. Even if you add a vent or two on the roof the fact that there's hardly any spacing between the rafters and the insulation would keep the vents from doing their job.
Cracking the vents inside the trailer will do nothing since they're not exposing the attic portion of the roof.
There's something said for solid block foam laminated roofs. No condensation.
Not sure if you''re still under warranty or not but I'd be contacting Jayco ASAP. All that water in the insulation is going to create mold eventually.

[JohnWedell]

Waiting for Jayco to get back to me about the condensation problem and installing attic vents. Just wondering if anyone has installed the mushroom type vents and if they worked.