Bonding & Skim coat advice please where salts are concer

[pgs0971]

About a year ago I replaced an original fireplace with a wood burner. The walls were damp either side of the chimney breast to about 800mm high on one side and only 150mm on the other. The wall adjoins a neighbours property. The property is 1890 built

I hacked all the plaster off back to the brickwork and injected some dryzone cream as the DPM looks almost non existent. I then used a bonding coat with a top coat of skim. In all this time (the walls that are facing the room) only one side has nearly dried out completely with the other still damp and a lot of salts/tide marks still showing. I was originally concerned that the damp was bridging at the floor so left about 30mm. A few months ago I raised this to about 100mm which although has improved the drying process slightly, it has still not thouroughly dried out.

My Mrs is keen for the wallpaper to go up but any ideas as to how I can cure the damp first. My neighbour says she has no damp issues on her side but I am aware that her chimney has been blocked which is directly the other side to where our damp is! This is why I used dryzone which I thought caused a barrier.

Should I perhaps inject the Dryzone higher up the wall?
Should I have used sand and cement instead of Bonding?

Thanks

 

[trowelmonkey1]

if you've still got damp after all this time then there is a problem somewhere that needs sorting, choice of materials used is irrelevant at this point.

has the plaster blown or is it still sound?

i presume the walls are solid?

you are getting damp above where you injected?

 

[Richard C]

Can't really add much except you’ve obviously still seem to have a damp problem which won’t have done the new plaster much good. Another thing to bear in mind when renovating around fire places is that conventional Gypsum plasters are only good up to 49 degrees C; no idea why it’s 49 degrees & not 50! If the temperature in the wall surrounding the fire regularly exceeds this, the plaster will in all probability blow & crack.

 

[roughcaster]

Should I have used sand and cement instead of Bonding?

Absolutely!!! Gypsum plasterer, (in this case bonding coat) onto old brick is not a good idea.

It would have been better to scratch coat the old brickwork, with waterproofer added, and then top coat render,, again, with waterproofer in. It is sometimes better to leave a neat, sponge finished render around a wood burning stove area, as that will cope with the heat much better than plaster.

Roughcaster.

 

[pgs0971]

Thanks for the replies.
The plaster has not blown at all.
The woodburner is set inside our chimney breast. The walls that show the damp are facing the room (ie to the right and left of the chimney breast) with the right hand side showing a much larger damp area (backing onto my neighbours chimney).
The dividing wall is solid brick but did feel damp to touch before I injected with Dryzone. The damp is still appearing above the injected area.
Could it be that I have not let the brickwork dryout sufficiently after injecting before adding the bonding coat and skim coat ?

p.s. Thanks for the tip of using Gypsum around the fireplace with max temp being 49 degrees. There is plenty of space / ventilation around the fireplace and have seen no signs of cracking / blowing during use earlier in the year. But for future ref and if the temp does cause the plaster to go is there an alternative that can be used at all ?
Thanks

Not sure what to do other than take it back to brick and reinvestigate.