The 20th century wasn’t a very good time for the old houses here in Wales. With time, many people forgot the traditional building and maintenance skills that gave us our old homes and helped them last so long.
Concrete, acrylic paints, wall insulation, and damp proofing materials have their uses, but older houses need the old skills and materials that made them work to begin with. ‘Old, damp houses’ were never considered old and damp before we forgot how to treat them.
It’s been almost 100 years since cavity walls became the building norm. Before 1919, our homes were built with solid walls. In Wales, stone was the material of choice, combined with lime mortars, pointing, renders, and lime wash on top. These materials worked well, dealing with our wet weather by allowing the moisture that got into the walls to work its way out again. Cavity walls, where two layers of masonry are built parallel to each other, worked differently. Creating two ‘skins’ around the house, builders could protect the inner layer from the dampness affecting the outer layer. If any moisture got through the first skin, the second was protected by the space between them.
The problem is that old, solid-walled homes have recently been treated in much the same way as new, cavity-walled homes. Attempting to stop or prevent dampness, we have covered and filled old houses with materials designed to stop moisture getting into the walls at all. If these systems were completely reliable, this wouldn’t be a problem. However, concrete, which sets hard and doesn’t allow for the movement of an old building as a lime render would, will almost inevitably crack on an old building. This leaves parts of the wall open to the elements. Then, when water manages to get inside, it can’t escape because of the watertight materials covering the walls. This leads to dampness, mould, and the deterioration of the walls themselves.
Ideally, a pre-1919 home would be restored using lime. Instead of concrete, lime mortars and renders would be used on the walls, and breathable paints would be used instead of the plastic paints that have become so common in recent history. If you are planning to restore an old home anywhere in the UK, contact Celtic Sustainables regarding its range of lime and breathable paint products suited to your solid-walled home.