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I have an Avondale Grampian which leaked and caused the wall and floor on the rear left hand inside to go black/spongy.I took out the wardrobe fitting and stripped back the ply boarding, but due to lack of space/time had to put van back in storage on a farm at the end of the summer.

I covered the van with a plastic tarpaulin which I hoped would prevent any more water getting in until next spring when I can get to it again.The tarpaulin reaches approx halfway done the side of the van.

I checked the van today and although the walls seemed dry inside, the floor in that same corner was wet and the "moisture crystal" container was full of water.

Anyone have any bright ideas how to track down where the water is getting in? I had a good look at it today but I'm stumped.

Also I notice that the aluminium side of the van is becoming badly pitted in places and holes are forming in a couple of cases. Has anyone else had this problem? Any suggested solutions?

Hi Richard i'd imagine most moisture containers would collect water this time of year even in a dry caravan , but even more so in a caravan that has a damp problem .
The most likely places for water entry are awning rails , then window seals , followed by grab handles , roof lights , locker doors . I'd be looking at awning rails , grab handles and window seals if there's a window close . Be aware that water can track side ways under the wall board , so the entry point may be further away than you think . Can you post any pictures of the area or email them to me .
If you do a search for   hole   on this forum you should find some good info on how to repair them .

atb

Wizard

Hi

There is a thing called "Osmosis", described to me as a form of aluminium cancer.

It's to do with how different metals react with each other in the wet especially if salts from the air (seaside etc) settle on the caravan, then small electrical currents can set up causing porosity (small holes in the aluminium skin).

One case involved a caravan roof. The caravan was kept under cover (a carport) but on a busy road. Much dirt (and salts) were blown onto the caravan roof and condensation drips from the carport supplied the moisture. The roof ended up pitted with holes.

If you're a C.C. member ring their technical helpline and they'll send you a leaflet on Osmosis. The most helpful part of it shows which metals to avoid when making repairs. I had one years ago but lost it now otherwise I could tell you more.

Tyreman

Do you mean 'Electrolysis', Tyreman? The same thing is a common problem with aluminium car and caravan wheels. The reaction causes a pitted surface around the rim of a wheel hence tubeless tyres leak. You think you have a slow puncture but the wheel rims need cleaning up.

Osmosis can have a very similar affect on fibreglass caravans but is caused by water penetrating a fibreglass gel coating and spreading throughout the inner fibres by capilliary action thus causing damage. 

Hi Bob

It was certainly called "Osmosis" by a local dealer, but you've made me scratch my head and look it up in the dictionary!

I agree that it is caused by "Electrolysis" (conduction of electricity by a solution) - probably caused by the use of dissimilar metals in caravan construction or repair.

I also agree that "Osmosis" (the passage of solvent molecules through a semipermeable membrane) is an excellent term for water penetrating fibreglass, but could also be applied to aluminium once it becomes porous through electrolytic action.

Perhaps a difference in trade language/ local terminology and "Osmosis caused by Electrolysis" is possibly a more accurate description.  

Regards

Tyreman

Although everybody on this thread is right, pinholes in the ally panels is commonly known in the trade as panel rot, water can pass through them & cause damp. there is usually a powdery scab around the holes, its not so easily got rid of as any repair to the outside is only a temporary repair usually. to do it properly a sealer is put over the panel then a new panel is glued onto it.

You could try stripping away the inner panel & infil & attack it from both sides, it might work.