I am sure someone here has seen it before and could explain this to me. I recently unblocked (blocked by some insulation) an airbrick in 1950s house , which 'opens' onto a vitrified clay pipe under concrete kitchen floor. The pipe hoes for about 3 m all the way to the front room (where the...
I have recently lowered the ground level at the front of the property and discovered that the 'mortar has been washed out' over the years? Or has it? Are there supposed to be gaps or should I fill them? Would normal mortar mix be OK to do it?
Thank you in advance.