'High damp' in chimney breast on survey

[CoffeeorBust]

Anyone know what this might indicate? We're considering whether to get a damp survey before exchanging contracts. There's no visible damp, just a wall reading as damp with a electronic reader.

The house is currently vacant, I'm wondering if it's just this?

Is the chimney disused?

a bricked-up chimney must be ventilated top and bottom or it will get internal condensation. That's very common but easily remedied.

Or if neglected, rain can penetrate from above. You can spot neglect by looking with binoculars for eroded brickwork, bad pointing, and faulty lead flashing. Wet patches on the brick may also be visible after rain. A wet chimney will often leave yellow or brown patches on the plaster, as the damp carries tar and soot residue.

Electronic damp meters are not very accurate. They work on wood, by measuring electrical resistance, but brick composition will vary with mineral content, which may have changed after historic damp.

BTW if you invite somebody who sells damp-proofing treatment into your home, they will advise you to buy damp proofing treatment.

Those meters are not for measuring damp and unless you're in a hermetically sealed box there will be moisture in the air.

There will also be moisture in the chimney. Check the link below and consult a surveyor who knows what they're doing. Not one who is so afraid of getting sued they reference everything regardless of whether it's present or not.

www.heritage-house.org/damp-and-condensation/the-ping-prong-meter-guilty-of-fraud.html

In my experience there’s always at least one damp reading on a survey. Unless you can smell, see or feel dampness, I reckon it’s safe to disregard. On its own, with no other signs, a damp reading on a chimney breast in an empty house wouldn’t concern me. Is there any mention of work needed to the flashing, or chimney stack? Has the chimney been capped and can air circulate?

If its a chimney breast there can be a few causes, including some mentioned above - lack of ventilation or cowl, lack of DPC on the chimney breast (common).

My money would be on salts.

As fossil fuels are burnt they produce salt compounds that often migrate through the brickwork and plaster. They can accumulate on the surface and trigger false 'damp' readings - moisture meters measure electrical resistance and salts conduct electricity. These salts also attract moisture in the air, which is something we have a lot of this time of year!

Top tip - often, if you boil a few kettles of water in the room with the doors/windows closed any salt damp problem will show patches on the plaster as condensation.

If it is a salt issue, the brickwork behind will be dry and it's not a real damp issue. Once the house is warm the issue should go away but replastering the chimney breast will solve it.

I would speak to the surveyor, he should be able to diagnose it, if not speak to a specialist RICS surveyor....not a damp proofing company.
Hope that helps!