Damp patches can occur in any historic building. It can appear on both exterior and interior walls. This is not a major problem as it can be dealt with quickly and easily. All it takes is some simple maintenance and understanding of the nature of historic buildings. The first step is to carry out a building check. Are the gutters blocked? Are overflows or drainpipes causing a problem? Often minor repairs and cleaning are all that is needed to deal with damp caused in this way.
Many surveyors unfamiliar with historic buildings incorrectly regard ‘rising damp’ as a major issue. It is basically a construction issue reflecting different ways of building homes. When constructing a modern building, a waterproof membrane is placed across the entire site. In addition, two layers of brickwork and the use of cement mortar provide an extra barrier against damp. Cement is impervious to damp.
Older buildings were not built in this way. Walls are solid and held together with lime mortar. Moisture passes through the lime mortar before evaporating. Unfortunately many historic building restorers and builders did not understand this process. Renovations and new additions to buildings were undertaken using different techniques blocking the evaporation process. Curing it simply involves removing the cement mortar. Another reason is change in lifestyles – people nowadays tend to open windows less frequently, or have high heating levels. Putting in air vents, ventilation fans and opening windows to create airflows around the house will make a difference.
Condensation on windows is another cause of the ‘rising damp’ problem. When temperatures are lower outside than inside, moisture forms on the windows. Over time, this moisture will rot the base of window frames. Wiping windows clear each day will help. Double-glazing is a long-term solution that householders tend to consider. Fitting standard double-glazing in a historic building is harder, if not impossible. Period windows have narrow glazing bars making double-glazing difficult to fit. Although very slim double-glazing can be obtained, not all conservation officers will accept them, as there is concern over reflection issues.
Secondary glazing is the usual option taken by householders and is recommended by window companies and heritage organisations. By fitting draught proofing to the secondary panel glazing it will reduce heating requirements within the room. At the same time, it will ensure that condensation does not form between the window and the secondary glazing thus avoiding rotting of the window frame.
Damp problems can be cured as long as you take quick action. The longer the situation is left, the worse it becomes and the harder it is to put things right. Begin by identifying the exact nature of the problem. Where is the damp occurring and what type is it? Seek advice from the Conservation Officer at your local council before undertaking any major work. They can advise on materials and techniques as well as recommending companies to use. Historic Buildings are subject to Listed Building Consent regulations and all work must meet those regulations.