Plastering options for terracotta blocks?

[Paulcarine]

Hi all. Just having some quotes for plastering my chimney breast up for a smooth finish and smooth inner too.

It's currently thick plaster direct on the blocks, after knocking it all back to the block. It's well stuck on there! options are to-

Dot/dab board on then skim - use hardiback board on inner?

Straight 2-coat plaster with a heat resistant render on the inner? - would this also need brick acid wash & and multiple sbr coats?

Thoughts appreciated.

 

[theprinceofdarkness]

Your chimney breast, did it have an open fire in it with out a flue liner?, then there might be acid within the bricks but as you can not knock of the present plaster, it would seem that plaster sticks to it very well.
Frank

 

[Paulcarine]

Yeah it looks like it may have had one at some point as there is soot in the old opening. - the old opening was bricked upfor a gas fire. it is the plaster on the outside of the breast that is well on.

 

[stuart45]

The grooves on terracotta blocks were normally dovetailed for the plaster to get a better grip.