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?
Aluminum issue
- Thread starter Jeep
- Start date
adrenaline503
Explorer
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
Expedition Leader
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
Explorer
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
We have had ours down to 10 degrees and not had problems with moisture or freezing.
Rob
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
Observer
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.
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.
Harald Hansen
Explorer
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.
John Speed goes a bit into the subject in Travelvans.
Ventilation is also important, to give the warm, moist air somewhere to escape.
DenCo40
Adventurer
Carl2500 said:
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.
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.
Bajaroad
Adventurer
Aluminum
The key is to prevent a metal pathway from outside to the inside, steel or aluminum (like some said).
I am designing my entire camper and subframe structure with aluminum. I'm only focusing on the subframe right now, but I've been working out the thermal insulation issues of the camper in the back of my mind.
-One possibility is to attached your aluminum sheets to your frame using 3M VHB (very high bond) double sided tape. This tape is often used to replace rivits. The benefit here is that it seals and insulates - the insulation is limited because of it's thickness, but it's a significant improvement over aluminum to aluminum. Many trailer mfgrs use this approach - really strong stuff.
-On the other side of the frame, the interior side, a layer of fiberglass or just a fiberglass or polymer stand-off which separates the interior walls from the frame. And of course insulation between the walls.
here is a nice application guide: http://multimedia.mmm.com/mws/mediawebserver.dyn?6666660Zjcf6lVs6EVs66Ser3COrrrrQ-
You could bond aluminum sheets to fiberglass sheets, which some truck camper mfgrs do.
I've heard some camper mfgrs will actually inject their aluminum tubing with a foam insulation, which I assume increases it's thermal capacity and slows it heat transfer.
one final thought, if you use an aluminum skin and attach it directly to a steel frame, you will also have the concern of galvanic corrosion.
The key is to prevent a metal pathway from outside to the inside, steel or aluminum (like some said).
I am designing my entire camper and subframe structure with aluminum. I'm only focusing on the subframe right now, but I've been working out the thermal insulation issues of the camper in the back of my mind.
-One possibility is to attached your aluminum sheets to your frame using 3M VHB (very high bond) double sided tape. This tape is often used to replace rivits. The benefit here is that it seals and insulates - the insulation is limited because of it's thickness, but it's a significant improvement over aluminum to aluminum. Many trailer mfgrs use this approach - really strong stuff.
-On the other side of the frame, the interior side, a layer of fiberglass or just a fiberglass or polymer stand-off which separates the interior walls from the frame. And of course insulation between the walls.
here is a nice application guide: http://multimedia.mmm.com/mws/mediawebserver.dyn?6666660Zjcf6lVs6EVs66Ser3COrrrrQ-
You could bond aluminum sheets to fiberglass sheets, which some truck camper mfgrs do.
I've heard some camper mfgrs will actually inject their aluminum tubing with a foam insulation, which I assume increases it's thermal capacity and slows it heat transfer.
one final thought, if you use an aluminum skin and attach it directly to a steel frame, you will also have the concern of galvanic corrosion.
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The condensation on aluminum is a common problem with Aluminum hulled boats as well. The french have been very successful at figuring out solutions.
Don't have any specifics to tell you but an internet search on condensation and aluminum boats will probably tell you all you could want to know.
Brian
Don't have any specifics to tell you but an internet search on condensation and aluminum boats will probably tell you all you could want to know.
Brian
NothingClever
Explorer
Bump for a brilliant display (in the link) of an alternative to rivets. Very interesting indeed.
Every Miles A Memory
Expedition Leader
I've never experienced the Aluminum Condesation thing because our camper is built with simple wood and fiberglass coating, but I'll agree that the propane and breathe is a major factor in the walls sweating.
Our windows sweat, the walls sweat and everything else feels a bit wet unless we keep the heater going non-stop to keep the temperature constant
One thing we've found that helps is to use a small electric heater which dries everything out....my nose included
Our windows sweat, the walls sweat and everything else feels a bit wet unless we keep the heater going non-stop to keep the temperature constant
One thing we've found that helps is to use a small electric heater which dries everything out....my nose included