I am keen to get out and take off and clean the rails so I can see how they are holding the batten in place, but it won't stop raining! I've got a tarp over that whole end of the caravan but it's fiddly to work under.
OK - so I am really fed up! I've taken back all the damp in one corner, and was looking to take off and reseal the external rails. However the rubber has perished, so just snapped off in little pieces. Meanwhile, the screws under the rubber have rusted away to nothing - I mean all of the screw, the whole length of the rail. Checking other rails, they all look the same, with loose seals and rusty screws.. I've found other patches of damp across the caravan, AND there appears to be new holes in the aluminium skin! I swear they weren't there last month!
I am seriously considering just patching up all the holes with expanding foam and duct tape until I start my new job in April, then scrapping the van.
You can buy the infill strip, not too expensive. I too have trouble with the screw heads rusting away. With some I've managed to cut a slot in what is left of the head and get them out that way. Others have come out after removing the rail by using mole grips on what was left of the screw.
I've not found any holes in the skin on mine though, thankfully. Don't know the best way to tackle those, but I have heard about that problem.
Just use sikaflex Or some form on PU18 to fill the holes - also good stuff for resealing your rails and gluing your wallboard.
Don't be disheartened it took us days to get off our rails and all the residue as our rails were glued on. It all seems like a lot of hard work but you'll break the back and you'll be pleased you did it yourself. Our damp cost us £123 to repair and we were quoted £1500 - nearly what we paid for the van.
All fixed now and I'm very chuffed we struggled on!
You'd need to replace the infill strip anyway as it gets brittle over years. I got O'Leary's to send me some when they sent the wallboard; didn't cost much at all and looks much neater new.
Also I had a rubber gasket around the rail too. Spoke to O'Leary's who said not to bother putting that back on. Looks better without.
Good luck!
Im sure somebody on Wizards website shows you how to remove the rail and screws when they have rusted in
I spent some time today looking at it all, I have some PU18 so went round taking off the smaller bits and pieces (grab handles, reflectors, toilet cassette hatch), resealing with the PU18 and screwing back on. A few of the holes where the aluminium has corroded are too big and will need to be patched, and I swear they weren't there when I washed the whole thing down last month!!
I think I'm just worried that there's damp the whole length of the van, eg behind the kitchen units. Doing a thorough job of sealing up the outside then running a dehumidifier for a few weeks might not cut it?
Maybe not. When I looked on the site about holes, a fibreglass car body filler was suggested that you get from halfords. I'll have a look and see what it is. You may end up patching with PU18 which is flexible and use some tape on the inside and trying to cover with some sort of decal.
Plenty of options for patching holes in the body. I'd stick a similar thickness piece of aluminium on the inside with pu18 allowing for it to ooze outside and seal the hole. Smooth with a wet finger and either place a badge/sticker over it or paint to match bodycolour.
PU sealants can be overpainted unlike mastic/silicone.
Great fix as I have similar problem at side of toilet in offside corner. No damp in rear wall next to corner but side wall at corner shows 38% moisture content immediately above cassette toilet reducing to 10% some 10 inches above toilet top and 10" in from corner so leak? looks as though it is restricted immediately to side of cassette area only but I cannot work out how to remove cassette in order to get at it. Can anyone help in this please?
Thanks
Doug