Aluminum issue

[Jeep]

I just looked at a couple of aluminum framed travel trailers that showed a flaw with using that material in cold weather. The aluminum builds up condensation very fast when temperature cycles (like when the heater cycles). The moisture collects in the walls and softens the interior panels, forms mold and rots the panels from the inside out. These are a popular trailer built for winter use and in both cases they were being used extensively in the winter, they are 2 years old. I was going to use aluminum in my camper but am now thinking of a light steel frame if it will reduce the internal condensation issue which I think it will because of the lower rate of heat transfer with steel. Anybody else see anything like this?

[adrenaline503]

I know on my ship our aluminum antenna mounts get a lot more condensation than the steel ones. Thus, they build ice faster when the temp drops. I always assumed that was due to the paint on the steel mounts, not a property of the metal itself. Its sense though, I prefer steel for anything structural anyway. I have seen a lot of aluminum structures eventually fail, where their steel counterparts do just fine.

[Grim Reaper]

The problem goes a lot deeper then you would think. YOU are part of the condensation problem. All the moisture that comes out in your breath helps to create the problem. I have an Airstream and its aluminum EVERYTHING. the exterior, interior and internal framing. Once you get the heater running its not a big deal and there is nothing to rot (except the floor).

[Robthebrit]

We have a late model Airstream, ours has the full metal interior and we have not had any moisture problems (other than the skylite leaking). Just like Grim Reaper said, once the heater is on all is good but using the vent in the bathroom and the stove vent is a must. When showering we have the vent runnind but in general we just leave it open to give a bit of circulation.

We have had ours down to 10 degrees and not had problems with moisture or freezing.

Rob

[Jeep]

The trailers I looked at were aluminum framed with panel (cheap wood) walls, they were used in temperatures as low as -40 C. There may be a difference there, the damage was rather ugly. How are the Airstreams as far as temps? Are they ovens in the summer and ice boxes in the winter? I may just go all aluminum construction but that is one of the concerns I had.

[RobinP]

Moisture condensing on aluminum is highly reduced once it has been coated. We used zolatone on the interior of aluminum truck boxes and boat dashes. We lined the ceiling of the New Cruiser with closed cell foam. This worked really well. Zolatone is a hard textured coating, and is quite expensive, but I think any of the cheaper alternates would work as well.

You're right though, aluminum structures need to be well designed to prevent fatigue cracking and weld failures, whereas steel is a lot more forgiving. Rules-of-thumb for aluminum design are not the same for steel.

[Carl2500]

I'd like to have an aluminum frame for my camper. Are there any cheap alternatives for coatings to prevent condensation?

[Harald Hansen]

The flaw is likely not the material, but the construction itself. If a cold bridge to the outside is formed, for example by using metal fasteners on a piece of metal framing, condensation will rapidly form there when the outside temperature drops. The outside skin of a camper should be thermally insulated from the outside. There are different ways to achieve this, for example fasteing the inside skin on wooden battens instead of the metal structure of the camper. Wood is a fairly good insulator.

John Speed goes a bit into the subject in Travelvans.

Ventilation is also important, to give the warm, moist air somewhere to escape.

[DenCo40]

I'd like to have an aluminum frame for my camper. Are there any cheap alternatives for coatings to prevent condensation?

You can't eliminate aluminums heat transfer properties which causes the attraction of condensation, but you can protect the aluminum from corroding by coating it. There is zinc chromate primer which is what we use in the aircraft industry to protect aluminum from oxidizing or you can clear coat it with a good clear coat.

[Jeep]

It's the damage to the insulation and panels that concerns me, I am probably going to use a light steel frame and powdercoat it as it seems easier to protect the steel rather than try and prevent the aluminum from doing what it does. I don't like the extra weight but properly designed it shouldn't add a whole bunch.