Hi thanks in advance for all replies and advice. After doing 3 years work on my house and in places taking plaster board back to brick ive often noticed how dry and powdery the inner wall mortar beds are.I could in places brush the mortar between the bricks out with a brush.....my house was built in 1930's. The house has been repointed in places on the outer wall but in places were this re-pointing has came out the external wall mortar beds are also very dry and powdery.....Its obviously a concern but is this normal or usual for the mortar to be so dry in a house of this age. Thanks.