Damp Meter?

[simondyntDBeK]

Hi,

The ceiling above the bottom of the stairs in my new home looks like it may be a little damp (the en-suite shower tray is immediately above it which is why I'm worried).

Is there a way I can check using a damp meter or something similar? I've seen a man press something against the walls when he came round our old house to do a survey - is this the same thing?

Ta

Simon

 

[KOR]

Think what your after is a moisture meter, should be able to hire one from your local hire shop.

 

[simondyntDBeK]

Thanks KOR - will have a look in HSS.

Simon

 

[ChrisR]

You can buy DIY ones for about a tenner, and if someone can tell me how they differ from "pro" ones I'd like to know. Afaik they're all just measuring electrical resistance to give a rough comparitive reading.

 

[sanj.varah]

the ebay, ten quid ones only have 3 settings from wet, to mildly moist and finally dry.

it doesn't actually tell you how much water is the in the wall as most walls have somewhere between 4-6%.

If you get a pro one, they usually go in 2% increments from 0 up to 40.

so i guess all your paying for is the sensitivity and the number of LED's

 

[Gasguru]

The damp meters with the pins that stick in the wall are a waste of time for accurate testing of wall/ceiling dampness - the're just a very rough guide and more for show by the unsrcupulous damp companies and surveyors.

They only test conductivity at the surface and different constructions and coverings give wildly different results. The indication they give often shows no correlation to actual dampness in the structure. Even a little condensation after cooking/bathing could show up as a major dampness problem.

The only accurate way to determine dampness is by taking a proper core sample and testing it.

Cut out a section of the ceiling to investigate the shower tray - its cheap and easy to repair the ceiling. Use a large diameter holesaw and mirrors to inspect. Its easy to glue the piece back in afterwards.

 

[^woody^]

A meter used correctly and the readings interpreted correctly can give an excellent indication of whether a particular area is suffering elevated moisture content to adjacent areas.

Whether any dampness is caused by penetrating, leaking or condensation dampness is another matter.

I would not recommend destructive testing, and the expense of laboratory testing to see if a ceiling is damp from a possible shower leak.

Yellow/brown staining is the giveaway, and a quick coat of white emulsion can often help to show any leak/staining

With a meter, you are looking for sudden rises in the dampness from one area to another. A meter with just 3 or 5 LED's is not any help at all

 

[simondyntDBeK]

Thanks folks,

There's no yellow/brown staining at all - it just feels 'wet'. It also looks like it may have been recently repaired/painted (probably just prior to us buying the property!)

Will see how it goes.

Simon

 

[jeds]

A damp meter is like anything else. A cheap battery drill will be perfectly ok for drilling occasional holes but won't last long if you use it 7 hours a day every day. Higher spec moisture meters will be more accurate than cheapo ones but more importantly they'll last longer and stay accurate longer. How do I know my Protimeter is accurate? It comes with a test bar which is a known resistance. Put it across the pins and the meter must read exactly 18.2%. If it doesn't it needs calibrating. I test mine occasionally and at ten years old it's still spot on. It also has a radio frequency measuring mode, which is non invasive. It can detect moisture up to 20mm below a surface - even through tiles and plastic coatings. The result is qualitative not quantitative though so it needs interpretation. But it doesn't suffer from the potential inaccuracies of electrical resistance measurement with pins. Mine also came with a set of remote pins on a lead and a set of long detectors for measuring moisture in deep screeds or concrete floors. You can also plug a set of slide hammer pins into it as well. Bear in mind that ALL electrical pin meters (cheap or expensive) are calibrated for use in softwood only. They tell you nothing about the percentage of moisture in walls. Which I suspect is what most people buy them for.