Roughcasting and Wall Coating in Edinburgh

Most of the harled housing in Edinburgh is not in the bit visitors photograph. The New Town and the Old Town are dressed stone in a World Heritage Site, and rendering them is usually the wrong answer and often not permitted. The work is out in Corstorphine, Clermiston, Colinton Mains, Sighthill, Gilmerton and the 1930s bungalow belt, where walls were harled from new. The east coast is drier than Glasgow, around 700mm a year, but it is colder, and freeze and thaw does more damage here than rainfall does.

Frost is the main enemy on this side of the country. A hairline crack takes on water in November, freezes, and opens a fraction each time it thaws. By spring it is a spall and the wall behind it is wet. Sealing that crack in autumn is a morning's work; leaving it is a re-dash.

The haar does not help. Long damp spells without real drying weather keep north and east elevations saturated, which is why the green growth on an Edinburgh wall is often worse than the rainfall figures would suggest.

On the older stone stock we are sometimes asked to render over sandstone that is perfectly sound. We will tell you if that is a bad idea. Covering breathable stone with an impermeable coat moves the damp problem inside, and on a listed or conservation-area property it can also land you with an enforcement notice.