Condensation under bed??

[dznf0g]

If camping where there is electric hookups, I use a small 200 watt personal electric heater in the trunk under the bed. Small temp differential = no condensation generation. Between that and a dehumidifier, I have never had wetness under the mattress.

[dkottum]

When we first bought this Airstream I closed the external storage hatch that goes under the bed, forgot to turn off the light inside, and noticed light coming out from around part of the hatch seal.

Cold air had a path to the inside, a good risk of condensation in the area in cold weather. So I removed the little locking arm of the latch, bent it so it would close tightly, and put in back on. No more light peeking out, no more cold air going in.

Check the hatch seals.

[dznf0g]

Originally Posted by dkottum

When we first bought this Airstream I closed the external storage hatch that goes under the bed, forgot to turn off the light inside, and noticed light coming out from around part of the hatch seal.

Cold air had a path to the inside, a good risk of condensation in the area in cold weather. So I removed the little locking arm of the latch, bent it so it would close tightly, and put in back on. No more light peeking out, no more cold air going in.

Check the hatch seals.

I wound up removing the bogus "seal" that AS installed and replacing with a double thickness EPDM tape seal (from big box store). I also ran a single thickness (thinner EPDM seal tape) in the piano hinge. I now have a 99% seal. I can run hose nozzle pressure and get just a drop or two in the piano hinge area, which runs harmlessly out onto the bumper.

[gsmithii]

Since my last post on this subject - "so far working pretty good" - the news is that with colder temperatures we did experience condensation under the mattresses. Overnight temperatures were commonly between low twenties and low thirties with condensation evident every morning. On one memorable night in Delaware we saw a balmy fifteen degrees overnight.

My next approach was to build a sandwich of Reflectix, closed-cell foam and a top layer of Reflectix. My choice for the closed cell foam was a half-inch layer of neoprene, the same general type used for wet suits.

We roll back into winter next week for a test. Will report victory (Yay!) or moisture (sigh).

By the way - with left over material I now have custom winter skylight covers.

[Rocinante]

I'll be very interested to learn whether the condensation challenge can be overcome without Hypervent or DryMesh.

Meanwhile, I'll bring along an extra roll of Reflectix for our next camping trip, just in case.

[chaseav]

Interesting thread. Call me crazy but wouldn't simply lifting the bed up, either on its jacks or by propping it up while the temperatures were in transit solve the moisture problem? That should work when the outside air temp is cool / cold but I could see why if it's hot and humid outside and you want it cold inside the moisture could happen. But to me that would mean I just had a bad seal on my outside door. I'm so new at this though my bed is still wrapped in plastic! .

[cwf]

Originally Posted by chaseav

Interesting thread. Call me crazy ..... But to me that would mean I just had a bad seal on my outside door. I'm so new at this though my bed is still wrapped in plastic! .

When you are inside your AS sleeping (after removing plastic wrap), your body heat and moisture your body naturally loses will be absorbed into the mattress. As that moisture is cooled by the underside of the bed which is usually unvented storage, the moisture condenses. PROBLEM!

You can totally seal the 'storage' area, but it will still 'cool off' because it is 'unheated space'. There is your target.

So, you can 'circulate' air through the 'storage' compartment to make it close to the same temp as your bed/trailer.... that will stop/minimize your condensation issue.

My recommendation, 'reflectix' insulation works ok for us in our 'moderate climate' by keeping the temperature from reaching 'condensation'/dew point.. point. We also added a 'mattress' cover which 'breathes' but blocks moisture... the hope is this will give more 'life' for the mattress which is realllllllly expensive.

On our AS, the 'hatch' on the rear is about 1 inch thick.. and has limited 'insulation'. In fact there may be NO insulation as far as i can tell because it transmits a lot of cold...but, my seal is pretty good...

If you 'push' air into the storage area from inside the AS, moisture will have a tendency to condensate on the inside of your storage area.. NOT a good idea!!! If you 'circulate' the air in and out, you will still get a chance for condensation due to the colder area, you may do just fine.... just have to work it...

If I ever take the 'hatch' door apart, I will probably fill with better insulation... till then, I keep it sealed as best I can and go with the bed insulation barrier... and keep a close eye on it...

One 'solution' would be to make another 'bed' layer on top of the existing so that you have some air space... then insulate UNDER the bed, inside the storage area to keep the cold from getting to the bed to begin with...

Lots of 'options'... good luck!

[chaseav]

Fascinating. In that "oh crap, I don't want to have to deal with this," sort of way. I haven't had the problem yet but being in the South moisture is a constant battle with everything. I'm convinced this place was entirely uninhabitable until the invention of the AC system.

[slowmover]

Originally Posted by chaseav

Fascinating. In that "oh crap, I don't want to have to deal with this," sort of way. I haven't had the problem yet but being in the South moisture is a constant battle with everything. I'm convinced this place was entirely uninhabitable until the invention of the AC system.

Yes, one would have to have an all wood house of a rot resistant variety. The raised houses of the 19th century lower Gulf Coast are the model.

Farther inland were the "dog run" houses.

With the advent of paved roads in the cities before the post WWII era and central air it was not for nothing a family which could afford it sent children and wives away by train for the worst of the summer.

The South featured shorter and illness filled lives, in general. This was offset by as much as three growing seasons. But not until malarial control, piped gas and electricity plus sanitary sewers became more common around WWI did life in the cities of the South resemble "civilization" as we'd think of it today.

We think little about insect control, and it is this which made Northern cities habitable with any population density. One depended on winter kill. And that we forcibly taught household hygiene to immigrants to control human parasites.

For trailers, a rolling dehumidifier in concert with the A/C for moisture control. Which is also insect control to some degree.

[Protagonist]

Originally Posted by slowmover

The South featured shorter and illness filled lives, in general. This was offset by as much as three growing seasons. But not until malarial control, piped gas and electricity plus sanitary sewers became more common around WWI did life in the cities of the South resemble "civilization" as we'd think of it today.

It's debatable whether New Orleans can be considered "civilization" even today. There's a reason why the "New Orleans: Third World and Proud of It!" bumper stickers were popular before Hurricane Katrina.

But back on topic, if you do see mold and mildew growth, the best environmentally-safe mold remover I've found is white wine vinegar. Here in the South, ventilation to prevent condensation will do much to slow the growth of mold and mildew, but nothing will prevent it entirely due to the naturally humid air.

[slowmover]

Greater incidence of disease, violence and more religiosity are features of tropical and subtropical climates worldwide. Natures mean is quite mean in those regions, one might say.

The shortest route to understanding a basic is in reading about sleep deprivation with wet bulb temperatures of 85F and higher at night.

Trailers have limits reached sooner than climate-adapted housing.

[TinTin]

Are y'all trying to make us northerners feel better on a January morning?

[slowmover]

Sure. Till we cut off the gas pipelines.

You may remember the irreverent bumper stickers of the late 70's 55-mph era that had it as:

Drive 75 and freeze a Yankee.

Seems ya'll have converted those oil burning power plants since then.

So I'll recommend a picture you might find online of the gas flares that light the oilfield at night. Who needs headlights?

[TinTin]

Sorry I posted. Rant on.

[Cannonball]

There is another recent thread on this topic. I have put down a layer of Reflectix under the mattress, but we have not had an opportunity to test the effective yet. I would point out that we have a Sport 22FB with the bed all the way at the front. The issue is the outside storage hatch and the outside storage compartment that runs the length of the head of the bed. My hatch seal is tight, it is just the door that is the issue. On the last trip, when I discovered this problem for the first time, I had observed condensation on the inside of the outside storage door on several mornings. I just did not two-and-two together. I am thinking that the hatch door has no insulation at all. I am considering cutting a piece of Reflectix and taping it to the inside of the hatch door, in addition to my other steps.

[chaseav]

I am a "damn Yankee" and proud of it. That's different than a Yankee of course. A damn Yankee is one who visits the South and then moves there. Frankly, I don't understand why anyone lives up north anymore. I'll take palmetto bugs and hurricanes any day over sub zero temperatures and feet of snow!

That aside, my door on my 25FB "feels" insulated. It just seems heavier than if it were hollow but I could be wrong. Mine is brand new so maybe AS got their poop in a group and made this upgrade. If not, I WILL be doing it myself somehow. Maybe this reflixtrix stuff.

Good post!

[samb]

I solved the problem in my trailer but putting a sheet of 1" RMAX foam insulation under my mattress. It has worked well down to less than 10* F outside temps. As mentioned before, it is the condensation of body moisture on a cold surface. The other 100% foolproof cure is to not sleep in the bed, or breathe while you are in the trailer. With those 2 ruled out, you are probably not making coffee or partaking in other moisture-producing activities so-------- problem solved.
Sam

[chaseav]

Originally Posted by samb

other moisture-producing activities

Hehe. Roger Wilco. Question: if I put down a piece of plastic underneath the mattress itself would the moisture condensation build up under the plastic (wood side) or mattress side? Or both?

[Protagonist]

Originally Posted by chaseav

Hehe. Roger Wilco. Question: if I put down a piece of plastic underneath the mattress itself would the moisture condensation build up under the plastic (wood side) or mattress side? Or both?

Plastic sheeting is a vapor barrier. What it will do is keep moisture on the same side it forms on. It will not by itself prevent the buildup of moisture.

There are only two methods of controlling moisture— adding ventilation and manipulating temperature. Ventilation consists of inserting a porous layer (dry mesh products) between the mattress and the top of the storage compartment.

Temperature control can take two forms. The idea is to make sure the temperature of all surfaces in the trailer is at least five degrees above the dew point. Condensation only forms on surfaces where the temperature is at or below the dew point of the air.

Insulation is one way to control temperature. But the best place to put the insulation is not necessarily under the mattress, since that does not allow the plywood to warm up above the dew point. You can insulate the door to the compartment so that the whole storage compartment is warmer. This is especially effective if you drill ventilation holes in the top and/or end of the compartment to allow heated air into the compartment. If the air inside the storage compartment is warmer, then the plywood will be warmer as well and condensation is less likely to form.

Another possibility is to heat the plywood directly, by the addition of heat tape. You can get thermostat-controlled 12v heat tape and lay it in a zigzag pattern on the plywood under the mattress so that the tape never crosses itself, then lay the mattress on top of the tape, possibly with a layer of Reflectix, Prodex, or even a Mylar space blanket (shiny side down) over the heat tape if you find it makes your mattress too warm for your sleeping comfort. Suggestion— If you try this, consider putting the thermostat unit inside the storage compartment, which is the side with the colder air. This will make the heat come on more often.

[Panama Red]

Or just install a couple vent grates in the end of the bed frame so that area gets some of the warmer trailer air... That ought to do it.

-Red, thinking inside the box...