Damp Chimney (with a difference) - Pictures attached

[paulburton]

Hi all,

Really appreciate anyone's thoughts on these pictures

Property built around 1810

Chimneys are closed at the bottom, and upstairs, but open chimney pots

This is the front room, house undergoing refurbishment, have had the paper off a few weeks and it's always looked like this, weather was dry the weeks before and still looked the same

I also own the property next door, exactly the same layout, chimneys also open, were capped at the bottom but now vented / open, but never had a problem when they were blocked or since opening

Last picture is when I was renovating the other property showing when I opened up the fireplace (just to give you an idea what the damp one looks like behind the plaster)

Is it damp coming up from the ground, or something to do with how they have made the opening smaller, and the sides are full of soot and absorbing the water coming down ?

Thanks all,


Paul

 

[ted456]

Your last pic shows a soot stained fireback wall. Bad.

The front room fireplace doesn't appear to be blocked off? What is blocked?
You show what looks like rising damp - this damp is typically coming up from the hearth soil infill.
If you crack out the hearth, & dig out the soil, you'll have an opportunity to examine the surrounding joisting (trimming) for rot.

All debris/soot needs removing, and the flues sweeping and smoke testing - soot stained fireplaces need to be wire brushed. Dry brushed.
The chimney stack, flaunching and terminal need examining.

All three surfaces of the c/breast needs hacking off and rendering with a 3:1 or 4:1 sharp sand & lime mix with a remedial skim finish.
Dont use any gypsum plaster.

Determine if you intend a decorative fire opening or an appliance installation of some kind?

 

[blup]

Some pointers from a DIYER - modern cementitious plaster can retain damp; the age of the building suggests there is no dpc or if one was installed it has failed or been bridged.

The floor itself may be laid direct to earth.

As you have found with the adjoining property, similar structures can react very differently.

If it is a listed building the local council may be able to offer advice

Blup

 

[paulburton]

Thanks guys, to clarify the questions

the last picture is my property next door I stood and boarded out the the fire place so wasn't an issue with the soot still there

Sorry, the fireplace is open (the one at the rear of this property is blocked up exactly the same but with no issue)

This is ground floor, with solid concrete floors and no DPM under, floors look mainly dry, plan to latex or similar with liquid DPC to level the floors and stop anymore damp

The hearth has been removed, but not sure what they have infilled it with, will get the plaster hacked off and look at chopping the floor out round it to see

Will probably put a cast iron fireplace back in, leaving a vent but boarding the back to stop the soot coming down

It is a grade 2 listed property, and as you say - properties react differently

Thanks both of you,


Paul

 

[paulburton]

Hi all,

Small update, I have now hacked off all the plaster, brickwork behind seems dry, I cleared all the debris from down the chimney - this was very dry so I am sure the damp is not coming down

The floor, I removed a think concrete infill, to reveal what I think is the original hearth - the rest of the floor appears to be bitumen in this room - no other signs of damp

So do I need to get the hearth out, put some membrane down and re-fill with cement ?

Could I just take out a few inches nearest the chimney breast and refill that after adding to DPM ?

Thanks all,


Paul

 

[tony1851]

Could be salts in the plaster?

 

[paulburton]

Could be salts in the plaster?

I'm sure it's damp not salt looking at the original pictures at the top of the thread