Edwardian detached internal walls damp

[Devlam]

Hi - first post here and I'm very much not a buildings expert, but thought I might seek some advice trying to id the root cause of a damp issue I have had for some time. I have a detached Edwardian house with a Chimney breast running up right through the middle of the house, i.e., there are rooms on all sides, all of the walls of the Chimney breast are damp up to around 2ft from the floor and the partition walls coming away from that chimney exhibit same kind of dampness. The damp patches get much worse after heavy rain.

The floor around the front of the chimney breast, which was originally cinder with quarry tiles on, was all replaced with new concrete slab and insulation some years ago and at that time a chemical damp proof course was put in (the damp problem was there before that) - that new damp proof course doesn't seem to have made a blind bit of difference. All of the external walls seem to be fine.

Could this be water just soaking under the external damp proof course - if so any ideas where I can start to look to get a remedy?

Thanks in advance.

 

[flameport]

The damp patches get much worse after heavy rain.

Rainwater entering the chimney, and soaking into the walls at the base.
Less likely is water collecting somewhere else, perhaps due to faulty guttering or similar, and ending up under the house.

Could this be water just soaking under the external damp proof course

No. Any damp proof course is unrelated to the problem.

 

[Devlam]

Thanks for the reply. We always thought it was rain coming down the chimney, but we had a cassette stove put in and when that was done the chimney was lined. Presumably any rain that got into the chimney would now run down and collect in the lining?

I took up some floor boards in one of the rooms adjacent to the chimney stack and the ground below the floorboards is wet, but if it's water down at that level, then that suggests rising damp, which given what you read on the web either exists or doesn't! As I said the chemical damp proof course that was put in hasn't made a difference.

Thanks again.

 

[bobasd]

so youve got a fire opening in a chimney breast and the floor in that room has been dug out and insulation laidand concrete poured over a DPMmeembrane.the walls and the chimney breast have been injected with a chemical DPC?
are you certain youve got a membrane and certain that the old hearth has been dug out completely?

thr room on the other side of the c/breast has a suspended floor? the ground below the suspended floor is wet? does the back of the c/breast have a fireplace in the suspended floor room?

odds are the c/breast has rising damp and maybe hygroscopic damp salts from sooty unswept chimney flue.

you can only find out how sound the stack and flue terminal are by going on the roof and looking.