I getting my driveway block paved and the guy also does building work, so i asked him what he thought. He thinks it might be sweating as the cavity is only about 10mm. He said try filling the gap with expanding foam but that might bring the condensation in on to the plaster. Failing that if...
Hi newbie here looking for advice.
I had a new pvc conservatory erected on an existing single brick dwarf wall. One large wall between my garden and the neighbours is double thickness. The company who erected it suggested I paint the wall internally with a bitumen type paint to damp proof it...