Forum Discussion

katoom400's avatar
katoom400
Explorer
Oct 13, 2014

Outback 250rs Rear Slid Condensation Issues

when camping in colder weather wifey likes her heat, she also does a lot of cooking on the stove and uses the oven occasionally. We experience a lot of condensation on the windows to the point the sills are full of water. Usually we are 4-5 people +50lb dog which produces a lot of water just from breathing.

at first we noticed the back corners of the slide where wet and the walls felt like they where sweating towards the bottom where the mattress hits the wall. We initially thought something was leaking from outside, but after testing with a hose it doesn't seem to be coming from outside.

This past weekend, it was only the wife, myself and the dog. We bought a 30 pint GE dehumidifier and ran it the first night which was ~45-50F. we noticed in the morning the windows where almost 100% clear and the slide walls felt dry! awesome...problem solved...I thought!

That morning it had rained a bit and was cool during the day. at night it dropped to about 32F, the heat was running pretty much non stop all night. the next morning we had some condensation on the windows, still much better than without the dehumidifier. However the walls still felt a little damp in the rear slide and if you ran your fingers along the edge of the rear slide wall, they came up wet.

I also bought a cheap humidity monitor which said the humidity was at 39% in the mornings. so I think that's pretty good, even our hands felt dry in the morning.

I just don't know what to check next, the moisture in the rear slide is unacceptable and you can already sense a slight mildew odor.

We love everything about the 250rs but the moisture problem in the rear slide, we don't want the trailer to go to crap, but don't know what else to try?

here is a pic of the rear slide for those not familiar with them:



  • We have the same slide in our model. The only time we had that problem was when heating the unit when the outside temp. was in the 20's.

    Only the back wall was affected.

    Haven't solved it, but think a dehumidifier is a good choice. .
  • Well, ChooChooMan beat me to it....this could be posted on the hybrid side of RVNet except that it's not a true hybrid, it's an expandable with some of the same issues.

    Forget boiling water inside later in the day. Air circulation is absolutely crucial and if you need to add a portable fan, so be it. Opening a window a bit has always been one of the suggestions for hybrids, but DH had no thought of letting that happen when he was trying to get warm, not let cold air in. Something to think about, though.

    The problem comes with the fact that the bed area is just sort of hanging out there and not sealed in the main part of the trailer...the temp difference causes condensation and there ya go.

    One thing we did with our hybrid and while it was not a 100% fix, it did help keep the mattress bottom dry - if you haven't checked yours you need to do so as it's likely damp - is to add a product called HyperVent, I think. It's used in boating applications a lot so if I'm wrong about the name, you should be able to find it. It lifts the mattress off the deck about an inch and allows a bit of air flow. It's not inexpensive....we bought it in '07 and for the queen size bed was about $106, so I'm sure it's higher now. Again, it is not a complete fix, but does lift the mattress above the bottom moisture.

    Our ROO had heated mattresses, which were wonderfully warm, but added to the temp difference. You could try a heated mattress pad or electric blanket for your DW, but the difference is still there.

    I have seen folks attach a heavy vinyl fabric along the edge of the slide and drops to the ground level, keeping out some of the cold in that area. Do not know how successful it was, but maybe worth a try.

    So the main things are no cooking on the stovetop with water based items in the evening, turn on the vent fan for as long as possible and with a window just slightly cracked, do your best to keep the mattress bottom dry and check it every morning - just wiping the deck dry with a towel will take care of the moisture on the deck, but we had some times before the HyperVent when we set a few cans of food under the mattress to allow it to dry out.

    One other suggestion that's similar to the Pop Up Gizmos we used with the hybrid is to make a stop at HD or Lowe's and check into a sheet of reflectix that could be temporarily attached to the top of the slide to insulate a bit more. The PUGS are made from a similar product and work wonders. Doubt that you should try to close up the slide with it attached, but maybe you could come up with a way to fold it or roll it up for storage.

    I doubt that you're doing permanent damage to the trailer, but until you have this under more control, suggest you wipe down the walls and windows in that area daily. FWIW, I have heard that many folks with 5ers have this problem if there is not enough space between the bed and the floor - again, temp difference. Good luck.
  • bid_time wrote:
    You might need to try some way to insulate the walls from the outside. Some kind of wrap type insulating feature. Basically, you need to keep the walls in the slide out warmer so humidity doesn't condense on them.


    Yes, I've considered that, but there is no easy way and I would cover the windows, seems like a PIA, If I can't have a $25k trailer not rot the slides out from the inside, I would just assume sell it and buy a trailer without slides.

    But before it comes to that I'd like to hear from people with the same trailer and find out if they have had this problem and if they where able to solve it.
  • You might need to try some way to insulate the walls from the outside. Some kind of wrap type insulating feature. Basically, you need to keep the walls in the slide out warmer so humidity doesn't condense on them.
  • Suggestions from a hybrid owner.

    1) Cook outside as much as you can. We never cook inside and don't have or want an oven
    2) open a roof vent, turn on the Fan-tastic fan and crack a window for air circulation.
    3) keep the inside cooler. I can camp down to freezing with just a 1500 Watt electric heater. Low to mid 60s is comfy.