Elddis Caravan Damp (long)

[ch...@newsguy.com]

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 workshop for repair. Then took it back for more work as she was not happy. She 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 professional 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 the front off-side window the reading was 10-13%. I stripped away the vinyl wallpaper 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 of wallboard under and in front of the window to expose the 'ribs'. These are discoloured in places but seem sound. Sadly the cut-away board broke up because of the soft areas but the damage to the ribs and polystyrene insulation was minimal. The rubber strip around the window socket has taken some grief during this process but the timbers round the socket seem okay. Externally the visible sealant above and below the awning rail, front rail and off-side window hanging rail is cracked.

I think the way forward is to re-bed the window hanging rail for the off-side window, replace the rubber window socket seal and try removing then re-applying the sealant above and below the other rails. I have some Caraflex caraseal IDL 99 to use to re-bed the hanging rail. Is it also good for resealing the other rails without removal? I know some folks use Sikaflex 512 for this but it is an adhesive/sealant, so the other rails may not come off if they need to be re-bedded in the future. Where is a good place to get a matching 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

[Roger Mills]

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.
--
Cheers,
Roger
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[Harry Bloomfield]

Roger Mills laid this down on his screen :

> 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!

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.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk