Damp on chimney breast - where to start?

[HMC2000]

A while ago I noticed a patch on a chimney breast where the plaster was a bit 'flakey'. Just a small patch, about 50 cm off the floor. It's clear now that there is some damp there, and google informs me that it may be rising damp, but is probably more likely to be damp coming in the chimney: the fireplace is completely boarded over, and has been since we bought the house 2 and a half years ago. I can see that if it is coming in from the chimney, I need to get the chimney re-capped, but I don't know where to start on finding out if that's the problem. Basically, what type of tradesman should I be calling? Do I need a surveyor? Should I call my house insurance and ask them? I feel ridiculously ignorant, and need to call on mn wisdom.

I am not an expert, but any closed up fireplaces I have had always had a ventilation grill in the area where they were sealed up so that the air circulates. Can you take the boarding off without doing too much peripheral damage and let it breathe?

Sorry, meant to add that a general builder would be able to fix it. I can't see that you need a surveyor.

We had damp on chimney breast caused by years of 'stuff' mainly twigs and bits of birds nest falling in and getting rained on through uncapped pot.it took us many years to work out what had happened and numerous unhelpful consultations by builders.
We cleared the bottom of the chimney and chimney sweep cleared the chimney then advised as to a chimney cap putteroner man!

Yeah I had to have mine capped too, otherwise as PP said crap just falls down it.
DP (different house) had to have his replastered and treated. He got the guy who'd originally treated it (several years ago) to come back and do it. he did a rubbish job though...

Thanks all! I was expecting tumbleweed I'm planning to open up the fireplace later this week when I'm not working, and am happy to get the caps replaced if they're faulty. I suppose what I'm really asking is who I need to get in to find out what the problem definitely is - I thought I should be checking to make sure that it’s not rising damp, but the only way I can see to do that would be to call in a surveyor to check damp levels along the wall. Is that not necessary? If I find out it's damp inside, is it fair to just assume it's coming down the chimney? I'm really hoping so. Sorry to sound so completely dim!!

Get a quote from a few people that treat damp. They'll come along and poke their machine on the wall and tell you where the damp is

people that sell damp proofing will tell you to buy damp proofing.

The first thing you need to do is to ventilate it top and bottom so there is airflow. If you cap the top, you must include an airbrick near the top as well as one near the bottom. You can have an elephant's foot fitted if you are fond of builders' curiosities and strange terminology. A chimney sweep may recommend someone.

Chimneys usually have two flues, one for the upstairs room and one for the downstairs. They must both be ventilated.

If you are certain that you will never again use the chimney, have it taken down below roof level and the flues left open in the loft. The roof will need to be remade over the hole. This will be less trouble in the long run because chimneys poking through roofs are a weakness and need periodic flaunching and flashing, and the pots fall off in storms, and they get water leaks.

This happens to me and DW when we first moved in and was caused by the flashings coming away from the chimney.

I'd first recommend getting in a roofer and get them to check the flashing (which is the metal bit - made of lead - between the bottom of the chimney and the roof) and whether the cement is crumbling between the bricks of the chimney. Repairing either of these things (repointing), as well as putting a new chimney cap is bread and butter for a decent roofer. You may even be able to self identify if this is the issue; if you can get in your loft and if there daylight coming in around the chimney breast then this is likely to be the cause!

If the chimney is on an external wall rather than between another house it may be penetrating damp. Again this is often caused by the cement between bricks being worn away over time and then rain getting through the cracks. You should be able to get a builder or specialist damp company in to sort it though.

Best of luck!

Yeah I also had the flashing and flaunching and pointing on my roof fixed, and a chimney stack re-set (it was wonky).
It was only a few hundred pounds I think, and only took a couple of hours.