Protimeter

Damp identified by survey is largely a scam area, so I'd be thorough about identifying what exactly is going on before anything else.

Looks somewhat similar to the log moisture meter I bought a few years ago for just under £20:

I'd never heard of pinless moisture meters. There's an informative page at

Needless to say, Wagner make only pinless meters, so tend to emphasise the perceived problem issues with pin meters.

You might be particularly interested in one of the comments at

What kind of damp has been identified? In what kind of wall etc. is it in?

and monitoring

Snake oil. Those things with probes will measure anything electricity conductive and the scam artists will tell you that it's damp.

I bought a moisture meter to check our motorhome for about £12 off EBay. It seems to give similar results to the numbers on the annual habitation checks - not conclusive as these are always low and around the same number ( thankfully!) but suggestive of it basically working.

It has two small ‘pins’ but they are too fine to damage the surfaces noticeably.

just don't stick it through foil back plasterboard

Worth noting that many pin meters are designed for measuring moisture levels in wood - and so can get "un-calibrated" results used on plaster etc.

Absolutely no experience of the pinless, but I have a couple of the pin types. Basically, you have to engage some common sense, as to how they work when you use them.

They measure conductivity, how conductive the material is - not much different from a multi-meter. Wet materials are more conductive than dry, but anywhere that rust (or similar) has migrated into the material, will remain conductive even when dry.

Best used as a comparison between known dry materials, to find moisture in similar materials.

I keep one handy in the clothes drying area, which normally cold, to check when clothing is actually dry, versus just feeling cold.

Or salts in completely dry plaster or condensation on the surface of painted walls etc.

Many years ago I was told that the proper way to measure wall moisture content was with a 3-pin meter, because that could account for contact resistance problems that can influence results using the 2-pin types. But don't ask me to explain it, and meters may be better days.

Lead paint in old properties......

That

Damp meters are widely misused on masonry, both in ignorance & deliberately. They are only suitable to measure water/damp in wood. Question 1 is exactly what symptoms of a damp problem do you have?

Yes, the Surveymaster needs a weighting (varies, depending on the wood) to be applied to the reading.

No idea! The Surveymaster's manual seems to suggest deeper readings using optional probes may be more accurate.

We're there any symptoms or signs of damp or is this a ploy to sell a treatment? Cynicism is always a good start.

For myself, I know they can be very misleading on masonry - so it'd only be a relative measure I'd be looking for.

Mainly ground floor, discoloured decoration and damaged/poor condition brickwork and pointing. There's also a damp cellar/exposed timber (which looks OK) and various measurements that raised concern throughout the building. Unclear of the cause - hence the need for some method of assessing how (relatively) damp the material is after each phase of remedy (ending with DPC for example).

That's not enough detail if you want help. Maybe you don't. Assessing by stage isn't really useful if you're doing the right things.

I don't need help with remedy - yet. It's more identification (hence the OP) and cause.

OK, noted.

Our damp came up in the survey. We had silicone injected, and it seems to have helped.

I recently noticed the paint on the fireplace was peeling. On closer inspection it was loos enough to just peel off, and when I checked with our firewood meter (which has a brick setting) the wall was really damp. Despite the silicone.

On closer inspection some of the paint layers were gloss, and presumably completely waterproof. So I peeled it all off - which was really easy - and painted it all with a breathable paint.

Stains came through the paint :(

But after a while the stains stopped growing, and the meter reported the bricks were _much_ drier. I need to get some lime mortar for a few little repairs, then I'll give it another coat.

I suspect the silicone stopped most new damp from coming up, but didn't deal with the damp already in the bricks.

It's about 300YO, so plenty of time for the damp to seep in.

Andy

Old walls tend to contain salts that electrical increase conductivity. The question that matters is whether there is a damp problem, rather than whether there is [questionable evidence of] damp, ie are there symptoms.