External fireplace chimney aesthetic problem...help please!

[JohnW]

Hi

We've an outdoor fireplace which is great except for the fact that the plaster is leeching chemicals (efflorescence??) and looks awful.

Can anyone tell me what's going on and suggest either a paint treatment or cladding ideas to cover up the bad look please?

Thanks

John

[tonyshouse]

Yes, efflorescence, basically moisture moving out is carrying with it soluble nitrate salts, most likely sodium nitrate. It will brush off but is forcing off the paint

 

heat will do this on its own even if water is not getting in through the top.

 

cracking is unfortunately expected and will be due to thermal movements, 

 

building in lime with lime render would solve most of the problems.