Buying a used caravan? - Let's talk damp!
If the van you're looking to purchase is under 10 years old then you need to be cautious and aware of possible damp issues. However, if you're looking for a caravan over 10 years old the chances are you're not really going to have much choice on the matter of damp as 80% of caravans over this age will have some damp somewhere or at least will have had at some point and will have dried out been repaired.
As I tell people, the main difference is you either know about it or you don't. I buy caravans every week, I'd say less than 5% of the people I buy caravans ever tell me when I ask if the van has damp, most swear there's no damp but I find damp in most of the vans I look at somewhere...so what does that tell you? A somewhat helpful comparison is caravans to similar age cars, I'd say that if you see a 2002 car with a certain amount of rust, chances are you'll see a similar age caravan with the equivalent in damp or "water ingress". That means when you're looking for a caravan you better know you can either trust the person you're buying off, have a good damp meter and know what to do with it or have the van damp tested yourself, BEFORE you buy!
Private or a dealer?
Private = no comebacks Dealer = the van must be described accurately, if you find damp or any faults not described when you bought it you are entitled to have it repaired or you can reject the van.
(or at least that's how it's meant to work!) - Check 2015 Consumer Rights Act for your rights.
Looking at a Caravan:
The first thing to look at when looking at a used caravan is the outside! Look up and down the awning rails at the front and back to see if there's any signs of degraded or missing sealant or opening up cracks or gaps. See if there's a gap in the middle of the van where the awning rails join at the top and seeing if there's a gap there, then looking at the seal around the door, the external lockers, water boiler, water inlet, tops of windows etc. If you can see a gap in the sealant then that's a likely sign there'll be water ingress in that area of the van. I like to put bets on to the person I'm buying off I'm looking at the van for when I see an open gap in the outside seal I'll bet them that there's damp in the van at that point, I'm usually right... I never get any money though...
Externally if you see any corrosion on the van then this would usually indicate that there has been damp behind that area for some time and is now eating through the aluminium.
If someone's gone around an area of the seals with silicone this is probably a sign there's been water ingress in these places too, this could however be a precaution. If the rubbery/plastic (herzim) insert strip in any rails is missing or has shrunk this can also let water in through screws in that rail.
You may also notice a van has or has had damp in the past as you may find lots of pin-holes where damp meters have been used to test the area, the bigger the holes the more soft you'd expect that area to feel. If these pinholes are very visible then either the person doing the testing wasn't very careful or there is evidence of ingress in this area and has been picked up by a number of people in the past.
The only way to prevent or keep on top of water ingress is to have your caravan serviced and damp tested every year so if you're buying it's worth asking and seeing service reports if they have them for the last few years to see if there's damp reading on there.
What constitutes as damp?
The average moisture reading of wood in caravan terms at least is about 12-15%. Anything above this means there's some moisture got into that area of wood. I'd say up to 20% isn't really anything to get your knickers twisted about but 25% and upwards is worth investigation. Anything up near 50-60% or above is going to have caused some structural damage to the van and will need repairing or using with caution.
This picture below shows what you won't be able to see, the moisture readings would be showing 40-80% and inside the wall when you chissel off the sopping boards you get to see the structural damage. At the top there in the corner the shaped ply-wood that gives the curve of the van structure was rotted completely away, the window frame also needed new timbers as the old ones had snapped and the wall of the van had lots some of it's strength.
So what if there is damp?
If you know there is water ingress somewhere in a caravan or motor-home up to 25% the thing to do is assess the outside of the van in that area to see if it's near a seam or door/fittings as this is likely to be where the water is getting in as explained in the previous paragraph. Generally over-sealing this area with some sort of decent sealant (domestic silicone or sealant will not last very long, CT1 (which we sell) or something strong like sikaflex will work best.
This may last a few years even but the proper way to repair is to remove the offending rail or door/fitting, clean it off removing all old sealant and re-sealing with mastic strip (adhesive sealing strip), "CT1" "seamseal" or "sikaflex" before putting back on the van and screwing it back in place. If a window seal has failed, the window rubber seal has to be removed and replaced... In some cases it is able to clean the rubber, re-apply sealant and re-fit (this doesn't tent to ever look quite right).
If the water ingress is over 50% and has caused internal damage to the boards then the chances are that the structure beneath the boards strengthening the caravan will be damaged and rotten too. In this case it's advisable to take the van to a workshop where the internal furniture in that area and the internal wall-boards will be removed, the damaged structure will be replaced and new wall-boards fitted. This will be quite costly. If the van is over 15 years old it may be something you wish to look into repairing yourself. This does take some level of skill so I can't advise you on this matter as if not done properly you could be taking big risks taking the van on the road.
So should I buy if the van has damp?
If you've read this far you can probably make an educated decision now. As I've tried to explain damp is just one of those things with caravans or motor-homes and is something that can be treated, if it has been treated then the moisture readings should go down over time as that area dries out or if the internal boards have been replaced then there should be no evidence of moisture at all. If the van has damp which hasn't been dealt with then depending on how high the readings are you can negotiate on price to compensate for the work which needs to be done. If the readings are around the 20% mark then you just need to keep an eye on that area.
If you'd like us to damp inspect a caravan you may be wanting to buy we can do this on a mobile basis for
£50/call-out and inspection within 10miles of NE25 0PP or bring to us for £40 damp test.
The information given in this article is provided with the best of intentions and to help you enjoy your Caravanning Experience. Information given is for guide purposes only, individuals must at all times use their own initiative while considering these matters and should seek proper legal advice if necessary.
There is no official legal advice in this article.
We accept no responsibility for damage to your vehicle or to any other form of material property and accept no responsibility for personal or third party injury that may occur in relationship to information provided in this article.