Elddis Caravan Damp (long)

Hello,
My mother has asked me to take a look at her caravan, a Elddis Tornado 1998 . It has an internal damp problem. She took it to a professional caravan wo rkshop for repair. Then took it back for more work as she was not happy. Sh e thought it was okay second time around, but the guarantee on the work has now expired and I do not think it is dry.
The damp is around the off-side window nearest the front. I hired a profess ional damp meter and took readings of 45% about a foot below the window, 37 % between the side of the window and the front of the caravan and 27% above the window and in the above locker. Around the front windows and behind th e front off-side window the reading was 10-13%. I stripped away the vinyl w allpaper over the damp area apart from in the locker. I found dark patches, mold and soft areas of wallboard.
Using a oscillating multi-tool (thanks Aldi) I have cut away a large area o f wallboard under and in front of the window to expose the 'ribs'. These ar e discoloured in places but seem sound. Sadly the cut-away board broke up b ecause of the soft areas but the damage to the ribs and polystyrene insulat ion was minimal. The rubber strip around the window socket has taken some g rief during this process but the timbers round the socket seem okay. Extern ally the visible sealant above and below the awning rail, front rail and of f-side window hanging rail is cracked.
I think the way forward is to re-bed the window hanging rail for the off-si de window, replace the rubber window socket seal and try removing then re-a pplying the sealant above and below the other rails. I have some Caraflex c araseal IDL 99 to use to re-bed the hanging rail. Is it also good for resea ling the other rails without removal? I know some folks use Sikaflex 512 fo r this but it is an adhesive/sealant, so the other rails may not come off i f they need to be re-bedded in the future. Where is a good place to get a m atching rubber seal? Apparantly there is a company that matches samples of the old rubber to get an exact fit. If I strip the wall paper in the locker can I paint the wall board with wood hardener after it has had a chance to dry? It would be a nightmare to replace the wallboard in the locker but I do not want to melt the polystyrene or anything.
TIA
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On 24/02/2015 13:53, snipped-for-privacy@newsguy.com wrote:

I'm sure this is not what you want to hear but, with a caravan which is 17 years old, you need to think carefully about whether it is economical to repair it. You can easily spend far more than the current market value trying to get rid of the damp - especially if you pay someone to do it - and the chances of success are very slight. It's almost impossible to re-seal it satisfactorily once a significant amount of damp gets in and even more difficult to dry it completely - so a damp meter will always see moisture even if no new water is getting in. I speak from bitter experience!
If Caraseal is the stuff I think it is, it's a putty-like substance which never completely dries - and only works between two surfaces. So if you do take on the repair job, you need to remove the trims, etc. and apply the sealant and re-fit them. It won't work, otherwise.
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Cheers,
Roger
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Roger Mills laid this down on his screen :

I will second that, but a lot of people do manage to do these repairs themselves.
Once the water gets in, it stays in unless you do something to enable it to escape. Stopping any more getting in is only a small part of the battle. The main part of the battle is drying out the moisture trapped between the inner and outer walls, which the professionals just completely ignore - it then percolates further between the two surface. What repairers often do, is fix the leak, give it a few days to dry, then fit new inner panels, which gets it out of the repair guarantee period, before problems once again show - all the time it rots away inside.
Any soft panel needs to be taken out, the wood checked and allowed to throughly dry out, but obviously not in this weather :-(
The same with the poly insulation. Only when it has properly dried, should you consider installing new inner panelling. Moisture trapped in the wall, can also rot or react with the alloy panel from the inside, causing pinholes.
Just to give you some idea how long it takes to dry out wet wood frame...
Mine had a damp spot in the panel next to the fridge, due to the fridge drain plug being left in place during the build. The wet spot was 15" inboard of a the wall, just a divider panel. I fixed the original problem, after which that small area, just a bit of 1" square wood, showed 60% and the rest <20%. I had a fan heater set low, blowing air on it for a month, to get it down to 20%. Turn the fan heater off and back it would rise to 30%. That was two years ago, last year it was still showing 27%.
A couple of vans ago, one I brought as a project, the owner had for some reason removed the roof light and refitted it without rebedding it in sealant. It didn't look too bad, until you started to touch the roof boarding. The entire roof, the wood ribs the entire panel was rotten. I ended up ripping the whole roof out, leaving the alloy in place and rebuilding it from the inside with new wood, new insulation and a new lining. The most difficult part, being getting the furniture out where attached to the roof.
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Regards,
Harry (M1BYT) (L)
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