# Using a damp meter help



## PAT4NEIL (Jul 21, 2007)

following on from my earlier post on a possible roof light leak.

I have purchased a damp meter ( digital device with two probes )

I appreciate that all matererials in the motohome have a an acceptable moisture content. 

the meter measures the damp as a percentage so my question is how can you tel what level is an acceptable percentage and what would be considered a high reading 

many thanks

Patsy 4 ( Neil )


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## MikeCo (Jan 26, 2008)

The ones that the dealers use to knock down the part exchange value of your van cost around £200 and when they stick it in the wall inside your cupboard it registers the bucket of water they have left out in the showroom.
If you have bought a B & Q one and it pings then you will have damp.
Thats my opinion anyway.


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## AberdeenAngus (Jul 26, 2008)

The damp meters use resistance between the probes as a measure of damp (since wet things conduct more than dry things).
In order to make sense of the readings you need something to compare it against.

They're not much use.


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## gaspode (May 9, 2005)

Rather than look for a specific percentage you need to compare readings taken in different parts of the van. At this time of year you're likely to find some dampness as the relative humidity in the atmosphere can be 80%+ and if the van isn't kept heated the surface will absorb some water.
Try the meter in different locations of the inside walls and look for areas that vary by more than around 10%, comparing readings midway up a wall with the area just below a window will usually tell you if there is a problem.


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## CLS (Jul 25, 2005)

The damp meters most dealers and engineers use are made by Protimeter and cost approaching £200. The readings below are what i use to determine damp in a van and what action is required

Damp readings between 0% and 15% acceptable
16% and 20% further investigation 
21% + remedial required

There are also other things to take ito consideration such as metal plates that may be present in the walls and alter readings , temperature extremes may give distorted readings ,etc....

Cheers Mark


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## Diver (May 15, 2005)

Mark / CLS – I’m looking at buying a damp meter rather than pay for a test each year now that our van is 3 years old. I’ve had a look at the range of instruments supplied by Protimeter. Which model would you recommend for a MH please?


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## time-traveller (Apr 23, 2007)

No matter how much or how little you pay for your dampmeter, Gaspode's reply is the most sensible approach - never mind what the reading are (within sensible reason!) - just compare the difference in readings between those areas that are unlikely to suffer damp (such as in the centre of a 'blank' wall) and those that are (such as immediately adjacent to a skylight/door/window.

It's a similar technique as reading a barometer - you aren't as much interested as to the actual reading but more in the direction that the needle jumps when you tap it !



gaspode said:


> Rather than look for a specific percentage you need to compare readings taken in different parts of the van. At this time of year you're likely to find some dampness as the relative humidity in the atmosphere can be 80%+ and if the van isn't kept heated the surface will absorb some water.
> Try the meter in different locations of the inside walls and look for areas that vary by more than around 10%, comparing readings midway up a wall with the area just below a window will usually tell you if there is a problem.


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## CLS (Jul 25, 2005)

The Protimeter Mini is a great meter easy to use and comes with extension leads for taking readings in awkward to reach places. When using one try to take readings where they are not going to be seen as you have to penetrate the wall boards for an accurate reading , around windows lift up the rubbers taking care not to touch the probes onto the rubber as this will show a false reading. Generally available for around £125.00 

Cheers Mark


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## Diver (May 15, 2005)

Thanks Mark


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## gromett (May 9, 2005)

I have the protimeter mini which I have found to be excellent. I did a few tests by soaking a length of wood in a bucket of water and testing down it. Amazing how quick wood soaks up water along a length.

Anyway, in use I use Gaspodes method. I had no idea what level was acceptable so just stuck it in all round the van looking for higher levels.
Found only one spot higher and that was in the middle of the floor (mine is a double floored jobby) which was confusing. Turned out to be a very small area just above the waste tank. Tightened the jubilee clip on the pipe and over the next 6 weeks the levels dropped to the rest of the vans.

Gaspodes method worked for me 

Karl


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## HARRYH (May 18, 2005)

*Dampmeter*

Hi
Just purchased a dampmeter from Hong Kong on ebay for approx £2 plus 
£ 7 postage 2 weeks delivery Its very sensative gives a clear digital read out from four prongs.
The readings in my 18 month old MH were 0% to 3% over most of the surfaces but I had a reading of 12 to 13% under a window. 
There is no obvious damp feel or staining. Should I be concerned?
Harry


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## helvic (Dec 15, 2007)

*Re: Dampmeter*



HARRYH said:


> Hi
> Just purchased a dampmeter from Hong Kong on ebay for approx £2 plus
> £ 7 postage 2 weeks delivery Its very sensative gives a clear digital read out from four prongs.
> The readings in my 18 month old MH were 0% to 3% over most of the surfaces but I had a reading of 12 to 13% under a window.
> ...


 hi what was the make thanks steve


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