Fireplace render/plaster type?

[Blade471]

Hi,

I've read through most of this forum and can't find anyone that has asked the same question.

We recently opened up an old fireplace (pictures attached) and our builders plastered it all up and seemed to have done a good job. However as you can see from the pictures it now looks like damp is coming through the plaster? However, a building friend of mine suggested that it might be from when the fireplace was a real fireplace and that sulphur (or something similar) is coming out from the old brick and ruining the fireplace. Apparently this is reasonably common and the look of it makes people think it is damp. I now want to get the plaster re-done so would like some advice as to what plaster the builders should use.....?

Any help would be much appreciated!

Thanks

Chris

 

[Micilin]

Have a search through this section.
I'd say you need to hack off, clean as much as you can and then seal it up before re plastering, ideally with a waterproof sand and cement.

Seal up with an SBR slurry or Bondit .it may take a few goes.

The important bit is to make sure it is sealed fully before plastering.

 

[ree]

As above.

Hack off all the interior fire opening plaster back to brickwork- and the exterior of the chimney breast to a height about 300mm above the last signs of salt damage. Remove all skirting around the c/breast while hacking off.

Wire brush the brickwork clean of all traces of soot.

Have the flue swept (have all your flues swept) and perhaps smoke tested. Flues, dormant or in use require thro ventilation up thro the stack.

As above, its a must to render back up inside and outside the fire opening in sand and cement etc.

You might find that the return walls on either side of the c/breast have been contaminated - examine them carefully.