The Market Place: brick, stone and a colonnade
Buildings in two different materials need roof work that protects both.
Bank House is early 18th century, red brick trimmed in stone, and the former town hall, from the early 19th century, is in Bath stone ashlar with a colonnaded front. They stand close together and use different materials, which makes the Market Place a useful lesson in how stone and brick behave under a roof.
Bath stone is a soft limestone. It is cut cleanly into ashlar blocks, laid with thin joints, and it wears from the surface when kept wet. A roof drainage fault near an ashlar front can do years of harm quietly. A cracked gutter outlet or a parapet that sheds water onto the face leaves dark streaks, and in time the stone itself starts to flake. The protection is above the stone: the lead, the coping and the gutters. We check these before anything else, and we repair them in materials that match.
Brick has its own habits. Red brick with stone dressings gives a roof edge made of two materials, so the verge or eaves meets surfaces that absorb water differently. Lime mortar is softer than the brick it holds and allows moisture to escape through the joint, while cement forces it through the brick face and can spall it. For repointing round a roof edge or stack, the mortar should be softer than the masonry.
If the building is listed, as several Market Place buildings may be, consent comes first, and it comes from Wiltshire Council. We explain the steps in order, so you know what has to be settled before a start date can be set. How we trace a leak on stone and brick buildings is set out under roof repairs.
Myth
Stone walls are strong enough that a leaking gutter beside them does not matter.
Fact
Soft limestone wears quickly when wet, and a blocked gutter or split lead can mark and decay the face long before a leak shows indoors.



