Roughcasting and Wall Coating in Glasgow

Glasgow gives us two very different jobs. There are the Victorian and Edwardian sandstone tenements, where the original work is usually a soft lime harl on solid walls, and there are the interwar semis and bungalows out through the suburbs, where the wall is pebbledash over brick or block and is now eighty or ninety years old. Both are standing in around 1,100mm of rain a year, most of it arriving on a south-westerly, and that is what decides how long any finish lasts.

The gable that faces the prevailing wind fails first, and on a Glasgow terrace or semi that is nearly always the south-west elevation. Tap along it and you get a hollow note where the roughcast has parted from the wall behind. Water is already sitting in that gap; the frost that follows is what takes the section off.

On tenements the usual culprit is a hard cement patch put over soft lime work. Cement will not move with the building and it will not let the wall dry, so the repair holds and the sound harl around it cracks away instead. We take those back and rebuild in something the wall can live with.

North-facing walls go green and then black. That is organic growth feeding on a surface that never gets sun and never fully dries. It is cosmetic at first and it is a warning: the wall is holding water it should be shedding.