crumbling interior brickwork -advice needed

[hwilson26]

just purchased a house built in the 1800's - there was water damage in one of the upper bedrooms so we removed the plaster to get to the cause. the brickwork in the wall by the chimney breast is damp spalling and crumbling, and affected by sulphates - my partner hs bought some KA tanking slurrey but I'm not convinced this is the best method for treating the brick and damp problem - any ideas? please help - getting confused over the best method to use

[welsh brickie]

tanking slurry should work,brush off all the loose material first.