Plastering of chimney on cold attic?

[larkar]

During the latest inspection of the chimney, etc., I received a remark that the masonry on the cold attic must be plastered. The house is over 35 years old and the chimney has never been plastered there before. What type of plaster should I use? Why is it being noted now?:S

 

[holmertz]

Hydraulic lime mortar gives you the same material as in the joints. Never apply harder mortar on top of one that is softer.

 

[sjalvdrag]

maybe gypsum thinks it is classified...check it out.