Best way to deal with hydroscopoc salts on chimney breast

[Sprocker]

hi all
Have a bit of a damp problem with all 4 chimney breasts in my house bit tackling the living room first. The damp is bang in the middle of the breast, the damp comes and goes but seems alot worse when its humid etc so im pretty sure is due to salts etc, also the roof was replaced and the flashing etc is all good. no damp proofer i have contacted or tried to contact without reply seem to want the work so thought i would treat myself. All the plaster is off the wall already to let the wall dry out abit.
I was thinking of neutralising the wall amd installing a membrane of some sort, then render and to finish it off with a multi finish plaster, but read up on other options like tanking etc so looking for some advise
Thanks

 

[bobasd]

please post pics of the c/breasts an the chimney stacks.

hygroscopic salts form in unswept, unventilated chimney flues.

all thats needed on the hacked off brickwork is a lime render an, say a limelite skim finish.

 

[noseall]

all thats needed on the hacked off brickwork is a lime render an, say a limelite skim finish.

Hygroscopic salts are aggressive and require a bit more attention than you suggest.

We would treat the area with an SBR slurry then sand/cement render the breast with SBR in the mix.

The alternative is a membrane and battens.

 

[bobasd]

if the flue is swept an through ventilated then the only salts left are already in the brickwork.
weve nearly always used a sand an lime 3:1 renders an, say limelite skim.
never had a come back call.

 

[lostinthelight]

The old remedy under lime render was supposed to be very fresh cow slurry.
I did a stinker of a tar leaking chimney using sulfacrete and been fine up to now.
https://theconstructor.org/concrete/sulphate-resistant-cement/23428/

 

[Sprocker]

Ok thanks for all the replys, just to confirm the chimney is currently open to the builders opening and still has the original pots on the stack so ventilation definitely isn't a issue, the damp has been there for many years as when I removed the 1980s wallpaper I found a nice sheet of tin foil on the breast to stop the damp coming through,

 

[bobasd]

Thats one flue - there are still three other flues?

A thorough sweeping is necessary - even using wire flails on stubborn flue soot.