Travel trailer rebuild question...

[Power Wagon]

I now have about 1/3 of all the wall coverings removed from my travel trailer. As some of you may know, it's all aluminum construction... built much like an airplane. I knew before it had some rotten areas in the wood interior panelling that were water caused, but I thought I probably had some leaks in the roof. Now, I've found that's NOT the cause for most of the rotten areas. I may still have some leaks, but it is definitely NOT the cause of all the rotten panelling.



Instead, it appears to have a condensation problem. Certain areas are sloped and channelled such that the condensation appears to collect and then get funnelled into small areas. Now, it does have a small amount of fiberglass insulation, but that's obviously not up to the task of stopping condensation from forming and running all over.



Anyway, I'm going to be starting the re-assembly process in 3 or 4 weeks (hope sooner!), and I'd like to find a way to stop as much as possible. I know, it lasted 32 years the first time, so what am I griping about, but... hey, if it can be done, why shouldn't I? What can be done to prevent moisture from inside (combustion of propane, breathing, cooking, bathing, etc) gathering all over the aluminum skin on the inside and then repeatedly soaking things up?

 

[Alaskaskiff]

Mark,



I think you want to use a good insulation and make sure you insulate everything! I think a vapor barrier insulation (the shiny foil/plastic boundary would help in this case. If you have anyframing that is aluminum you may want to get some insulation between the interior and the frame as well. The manufacturing process is not always known for its attention to detail. If they got 32 years, a little quality effort will get you 50. Good luck

 

[moparguy]

PW, I'm currently dealing with the same issues in a aluminumn horse tralier that we're gonna install a weekender type setup in. The dressing room (5' short wall, 10 1/2' long wall) is outfitted like a little RV.



Someone suggested having the trailer walls sprayed with expanding foam type insulation. Then of course install paneling. Total coverage, and no shifting years down the road were the suggested benefits.



One thing to remember on heating/cooking is that burning propane, any gas for that matter, is gonna produce a lot of water as a by-product. Good venting is really worth the time to engineer and install, along with insulation to help keep condensation down.



Don't know how you plan to heat the camper, but invest in a quality CO2 detector. It's worth the cost just for piece of mind.



Good luck, Ronnie

 

[Alaskaskiff]

Good venting will make a huge difference as well. If you can get some airflow the moisture problems will definitely be less. There are diesel fired alternatives to propane stoves (wallas) and heat (espar) that would really help on the moisture issues.

 

[Champane Flight]

I agree

I agree a good moisture barrier will help considerably. Just a plastic/foil barrier between the inner walls and the insulation. I will have to do the same to my old Hitchiker soon, as well as replace a little rotting in the rear framing. Good luck.

 

[Doc Tinker]

I agree with the suggestions for ventilation and insulation with a good vapor barrier. You should probably tape the barrier sheets together too. Also, Meijers sells a moisture absorber, in cans, that you can place in your trailer when it's parked. I think the cans of desiccant will help dry up any moisture that remains after you've used the trailer.



Doc

 

[Shovelhead]

Take a trip by your local Harley dealer.

H-D packs a bag of desicant in every crated bike that leaves the factory. When unpacked, the dealer usually throws it away.



Another tip, each crate has two approx. 6 foot ratchet type straps holding down the bike in the crate.

Check with the service guys, they'll probably GIVE you a dozen out of the pile they collect as they uncrate bikes. They are VERY handy to keep on hand for quick tie downs, and the price is right.



It's probably the ONLY thing free at a Harley dealership.

 

[Extreme1]

Spray foam insulation would do the trick too. Or insulate and tape the seams.

 

[Power Wagon]

Nobody in town stocks any foil faced insulation. Heavy paper, yes, but not foil. I recall it being referred to as "vapor barrier". I was told it's pretty much gone out of style.



So what if I used plastic sheeting? I mean, put in new paper-faced insulation duct-taping it in place to seal the airflow, then plastic sheeting and then the 1/4 inch underlayment for the panelling?There would be holes around the windows, door, and other openings like vents, but I suppose they could be sealed off somehow.



On the other hand, wouldn't that just seal in the moisture that's there and never let it out?



If I just put in the paper (they called it, Kraft-faced) faced insulation, I know that would cut down the condensation. As it is, it has about 1 to 1-1/2 inches of fiberglass batting in there, and anywhere it's not totally covering the aluminum, it's downright drippy. Of course, the trailer is presently being heated with a 1500 watt electric heater all the time PLUS a kerosun unit when we're in there working. I could just tape the insulation to the aluminum ribs leaving no gaps like there are now...



The spray foam sounds interesting, but I'm totally unfamiliar with it. I thought it was injected into the walls where it sort of expanded and hardened up.



Oh, and my budget is pretty skinny on this.



What I find interesting, is that on the roof, the aluminum ribs are arched about an inch or so in the center, and shaped to fit a 1X3 inside them. Not a one of those 1X3's has any sign of water damage or rot.

 

[Alaskaskiff]

Here is what you are trying to avoid: The cold aluminum shell condenses water out of the warmer inside air & therefore the moisture in the walls. The insulation makes it so there is not the large temperature differential to create the condensation. The vapor barrier prevents added condensation to be pumped into the system and with enough insulation (any is better) the vapor barrier will have no condensation because the cold exterior wall can't cool the vapor barier. Just think of a cold pop can on a warm day. This is the camper scenario (of course from the inside). Many paths to the same result. Anything that exhibits the characteristics above will work. Some of the marine foam is also closed cell so it could serve both functions.



Of course insulating makes it easier to heat and cool.



A ventilation means will keep the humidity as low as possible. The propane systems introduce large amounts of moisture, which is why I suggested (albeit expensive) alternatives.



Good Luck.

 

[QRTRHRS]

Mark, are there roof vents? If not they are easy to put in and you can get them with fans to assist. You can also get covers (forget who makes them) that mount permanently on the vents to keep out rain, allowing them to be left open. If your letting moisture out the top though, you need to let some air in below to allow the inversion. Maybe jury rig up some kind of weep hole vent, keep a window cracked open or something. When the trailer is parked for storage and the outside air warms faster than the trailer inside, you get a lot of moisture buildup. That will happen regardless of insulation type or moisture barrier. For those occasions, a small electric heater will keep it dry provided you can plug in.

 

[Briar Hopper]

Don't use duct tape, not the plastic, cloth-reinforced gray stuff you can buy anywhere. It will NOT last, it will NOT hold. The adhesive breaks down over a short time... . The HVAC supply houses can sell you foil-backed tape that the pros use on actual duct work, that stuff WILL last longer. Even the clear wide scotch tape from 3M made for box sealing & shipping, would stick to the paper backing of the insulation much better. You can't find vapor barrier in your area? Go to a bigger city. Home Depot, Lowe's ?

 

[LarryB]

PW



Go to the auto parts a pick up a spray can of 3M rubberized undercoating. It will prevent condensation and add a slight bit of insulation value. It dries hard and won't smell,goes a long way and quite inexpensive too.



Check it out.

 

[Steve Campbell]

"Grace" makes a roofing undercoat, to be used in place of 30lb felt down by the eve of the house called comething like "water and Ice barrier". It is a fairly thick "rubber" with an adhesive back. If you put a nail or screw through it, it just seals up around them. I am thinking that if you (carefully, because it is really sticky when warm) stick it to the inside of the skin and then insulate(The foam is actually a pretty good idea, but also expensive, come to think of it, so is this stuff) the rest of the space behind the panneling and put a heavy mil plastic just outside (behind) the panneling, you will have a better finished product than came from the factory. JMO



Any lumber yard, Home Depot, lowe's should have this stuff.

 

[Sled Puller]

Think about your house roof. You needa layer of dead air to work properly. RVs don't have this, so they eventually rot.



Find the aluminum sheeting with plastic bubbles sandwiched in btween, that will do better than fiberglass.



Gene

 

[LarryB]

Notice how moisture condenses on a smooth surface but seldom on a rough one. Notice how it condenses on aluminum windows but not vinyl. Just spray on the rubberized undercoating. Rough rubber surface = no condensation. Cheap, simple, durable and easy.



I've had moisture condense behind insulation before, even with a very slight airgap. The only way to truly prevent it is to ventilate well and change the surface.



FWIW