Damp meter readings, how much is acceptable?

alwaysared

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Okay, I've been to see the Hymer. The owner told me that they had damp in wardrobe and garage but it had all been repaired by the local Hymer dealer and it passed it's habitation check last November. So I used my damp meter that I got off Amazon and too my surprise the highest reading was 6% until I tried under the kitchen window where it was 49% and one part of the garage was 47% Would this be acceptable? Should it have been picked up in the habitation check? There is no visible evidence or smell of damp. They have the full service history from new and all the damp repairs are documented.

Regards,
Del
 
With any older Hymer, the biggest damp problem will usually be in the wooden floor. The sides and roof are a aluminium sandwich with heavy dense foam in-between , called the Paul System.
There should be no wood or possibly very very little in the van you are looking at.

It's a 2006 model and there seems quite a bit of wood in the garage area.

Regards,
Del
 
How reliable is your damp meter? 6% is extremely low, and is the kind of reading you would get from kiln dried compressed blocks for burning in a wood stove and stored in poly wrap. Kiln dried timber for furniture would be around 8 -12% and furniture in a well heated house should be around that level. Wood stored and dried outdoors under cover for a couple of years will be around the mid to high teens, depending on the season.

49% is extremely high and would probably feel damp, or even wet and liable to rot. It's more likely a spurious reading which could have a number of causes. Treatment with preservative or varnish could cause the reading to be an error as the electrical resistance would be affected. To get a proper reading you have to push the pins as deep into the wood as they will go without damaging them. This might not go down well with the owner.

The other method, which I used to do occasionally when making furniture, was to cut samples from the boards, weigh and dry them in an microwave oven until their weight stabilised and do a calculation. This is very accurate. Again, the owner may not appreciate this method being used.
 
Had a small hole in my roof once where water poured in so the roof was soaking, plugged the hole and after a few days it read 22 to 26 % wet so 49% would be a no-no from me. Walk away.
 
I’d want to check the damp meter against another known proven one. Something I’ll do with my cheap eBay purchase before relying on it
 
Anything over 25 walk away but as others have said check your damp meter. The thing about older vans, whatever their make, is is that you don't know if some person with handyman skills has attempted modifications that they really didn't know how to do properly. Damp issues are expensive to fix properly and the drying out process can be at least 6 weeks and that's with a stripped out van. If you gain them after purchase and love your van you might bite the bullet but I wouldn't buy them. Mine has a quote of £3000 on it for damp at present and that's cheap by some standards.
 

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