Damp tester

[tapdave]

I have just purchased a damp tester . I have used it and have been shocked that my interior is reading wet everywhere .

However through a process of illimination it seems that all wet readings are very close to metal aluminium strips ..I was agast and most concerned but I now know it reads wet even when I put it on anything metal , even on a screw driver or screw head ,,,please can I ask if these testers are accurate.?…I bought it from Temu and was about £30… the reviews were excellent??mmmm’. Thank you all

 

[Googlebot]

In a word, yes.

They only work on wood generally though I have found.

 

[Terry]

What readings are you getting?
Upto 15 is good 15 /25 needs investigated (damp) 25/30 is damp
30 and above is wet so don’t buy

 

[Kannon Fodda]

Damp meters were originally designed and calibrated for moisture content in wood. "dry wood" inside a heated building is still likely to have a moisture content of 7%-9%. Use on anything else can have variable results and you need to be able to understand what the meter may be telling you along with other clues from the environment.

Pin type meters work by trying to pass a small electric current through the material into which the pins have been pushed. If moisture is present the current moves with less resistance. But in materials like plaster, brick, concrete, natural salts and other chemicals can affect the conductivity and thus give false readings. Frequently "damp" in buildings can be the plaster having salts that have been drawn from brick into the plaster.

The modern, non invasive, meters try and work by radio frequency or capacitance of the material. Possibly OK where the material itself is uniform in thickness and density, but voids such as small gaps in brick or concrete will upset them. Of course, where they are being used in a motorhome and the materials are thus thin, anything immediately behind such as the metal skin of a panel van, wires, and such like can give false readings.

So damp meters are a useful diagnostic tool, but one then has to look further to understand what it may be telling you.

 

[tapdave]

Damp meters were originally designed and calibrated for moisture content in wood. "dry wood" inside a heated building is still likely to have a moisture content of 7%-9%. Use on anything else can have variable results and you need to be able to understand what the meter may be telling you along with other clues from the environment.

Pin type meters work by trying to pass a small electric current through the material into which the pins have been pushed. If moisture is present the current moves with less resistance. But in materials like plaster, brick, concrete, natural salts and other chemicals can affect the conductivity and thus give false readings. Frequently "damp" in buildings can be the plaster having salts that have been drawn from brick into the plaster.

The modern, non invasive, meters try and work by radio frequency or capacitance of the material. Possibly OK where the material itself is uniform in thickness and density, but voids such as small gaps in brick or concrete will upset them. Of course, where they are being used in a motorhome and the materials are thus thin, anything immediately behind such as the metal skin of a panel van, wires, and such like can give false readings.

So damp meters are a useful diagnostic tool, but one then has to look further to understand what it may be telling you.

Oh thanks . Some very useful info thank you . ,may I say I’m a little relieved as although I know I have had some water ingress in my CV roof the tester had me thinking my fiat was a right off !
my tester is not pronged but is one you just hold onto the surface .
I am a lot happier .thankyou for all reply’s .

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[Googlebot]

Oh thanks . Some very useful info thank you . ,may I say I’m a little relieved as although I know I have had some water ingress in my CV roof the tester had me thinking my fiat was a right off !
my tester is not pronged but is one you just hold onto the surface .
I am a lot happier .thankyou for all reply’s .

Some great advice from Kannon Fodda.

I didn’t realise it was one without prongs, I thought it was expensive from Temu. Think my prong one was £15 off eBay and it is quite accurate.

 

[tapdave]

Some great advice from Kannon Fodda.

I didn’t realise it was one without prongs, I thought it was expensive from Temu. Think my prong one was £15 off eBay and it is quite accurate.

Yeah it just has a spherical ball that sits at the top of the tester and you just activate it and draw it over the surface . As I say when I get near aluminium frames or metal it explodes it very wet indication. ..I was a bit dubious about using the prongs as they puncture the surface ..? What do you think ? Thanks

 

[AdrianChen]

I use an old Sovereign meter that was originally bought for surveying GRP and Wooden boat hulls, it hasn't been recalibrated for some years but works fine. It has both prongs and a flat pad for different materials. When checking a hull for dampness, it was always possible the meter would over-read if there were things like water tanks etc inside the hull at that point, but generally you can check to see if there is anything that would give a false reading. Difficult to say if it is accurate though (at £30 vs a Sovereign at around £700 for the modern version), and perhaps it's best used to locate areas that show a different reading to a known dry area, so you can investigate if there's a possible cause for the apparent reading.

 

[Googlebot]

Yeah it just has a spherical ball that sits at the top of the tester and you just activate it and draw it over the surface . As I say when I get near aluminium frames or metal it explodes it very wet indication. ..I was a bit dubious about using the prongs as they puncture the surface ..? What do you think ? Thanks

I use pins, I just test where I won’t see the holes.

 

[tapdave]

I use an old Sovereign meter that was originally bought for surveying GRP and Wooden boat hulls, it hasn't been recalibrated for some years but works fine. It has both prongs and a flat pad for different materials. When checking a hull for dampness, it was always possible the meter would over-read if there were things like water tanks etc inside the hull at that point, but generally you can check to see if there is anything that would give a false reading. Difficult to say if it is accurate though (at £30 vs a Sovereign at around £700 for the modern version), and perhaps it's best used to locate areas that show a different reading to a known dry area, so you can investigate if there's a possible cause for the apparent reading.

That’s an expensive meter ,wow! ..however that’s required for the boat purpose for sure . I have tested in an area that was wet that I have hopefully repaired .it reads risk so I believe it does work as it looks dryer than it was . Thank you for your input ..it all helps

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[tapdave]

I use pins, I just test where I won’t see the holes.

Ha ha .. I guess out of sight out of mind !

 

[Googlebot]

Ha ha .. I guess out of sight out of mind !

Yup.

I don’t test unless I think there is a problem either. I know I should, but it minimises holes.

 

[Bessy765]

Here is the readings from ours, 2019 Burstner a Class, luckily. It has the ten year damp warranty going in next week for repair, across the bottom of the back wall of the garage, second photos lower reading top wall back of garage.

 

[Googlebot]

Perhaps I should check more. :-(

 

[bombero2011]

Oh thanks . Some very useful info thank you . ,may I say I’m a little relieved as although I know I have had some water ingress in my CV roof the tester had me thinking my fiat was a right off !
my tester is not pronged but is one you just hold onto the surface .
I am a lot happier .thankyou for all reply’s .

Mine appears not to have prongs, but you pull the end off and it exposes the prongs, which incidentally you don't have to dig them in hard

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[Tantalus]

Mine doesn't have prongs. It has settings for various types of places to test from soft wood to brick walls.
I was surprised to find that the solid wood drawer front in my camper read 21%. But apparently that is normal for wood!
I have found damp spots which is going to be dealt with very soon. I'll post if there's anything interesting to report.
2002 Autotrail.

 

[gwyntaxi]

Here is the readings from ours, 2019 Burstner a Class, luckily. It has the ten year damp warranty going in next week for repair, across the bottom of the back wall of the garage, second photos lower reading top wall back of garage.



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Wow, those are high readings, must be quite a bit of damp there, just as well its booked in soon.