Dampness in building elements

Measures to protect the wall base at low level often encompass a combination of remedy elements. In the Wallington's hundred-year floor we see the running of a new wall base plinth together with new floor ventilation arrangements. In the To manage or cure? case study, the wall base is shielded by a protective cementitious plinth, and new perimeter drainage installations help guide water away.

When elevations suffer deterioration, whether damage to masonry units themselves or erosion of the jointings, too often the decision is taken to coat the elevations with renders. A quick, clean wall finish can be achieved, but a dense wall finish whose prime function is keeping dampness out could also keep dampness trapped within – as the balance may or may not be right. Once walls are cement rendered or painted, the finish will nearly always be very difficult to completely remove. However, there will be cases where the removal of impervious coatings might be the only way to return the property to its original functioning state. Sometimes cement plinths are applied far too high – so as well as shielding the wall base from low-level damp penetration, they act to hold dampness within the wall, where it can no longer efficiently evaporate out. They can also bridge the physical horizontal dpc, enabling ground based dampness to rise in the wall above the dpc.

External walls can be simply repaired where damaged brick faces or missing pointing enables damp penetration. Stones or bricks will of course need to be carefully matched, and it will take time for the new bricks to blend in with the existing as they weather over time. Where matching bricks are difficult to obtain, weathered bricks are sometimes cut out and reversed – the inner face may well be in good order.