Anyone who has lived in a pre-1940s building – one with solid wall construction and no damp-proof course – will appreciate the importance of what we call ‘damp management’. We describe it as management because inevitably with an old building, damp will be present in some form, and the purpose is not to eliminate it altogether but instead ensure that it is at an appropriate level for the building and its occupants.
Damp is one of the biggest risks to old buildings,
therefore having a strategy to manage it is key when living in one.
Condensation on the windows is a symptom of inadequate ventilation and a cause of damp.
Essentially, damp is excessive moisture in a building, which either directly enters the building (often through a failure), is diffused through the air or condenses on a surface. Ironically, the worst cases of damp in historic buildings are not caused by the building’s construction or its age, but likely by one of the following:
- modern alterations which change the way the original building was designed to perform — the addition of cementitious pointing, renders and non-breathable internal finishes;
- lack of maintenance — a leaky roof, blocked gutter or building failure;
- or lack of adequate ventilation — highlighted by moisture build-up from hot showers or drying washing.
This can sometimes mean that the management of damp is easier, cheaper and more straightforward than you might imagine. However, identifying the type of damp present and diagnosing its root cause is key, and this will inevitably lead to the solution or management strategy.
We always recommend the Old House Handbook by Roger Hunt and Marianne Suhr to our clients. It takes a pragmatic approach to owning an old building and the section on damp is particularly good at demystifying the subject.
If you are struggling to diagnose the source of the damp problems yourself, seek advice from a professional. A registered architect or surveyor who understands old buildings is a good starting point, and if the issues are more complex they may recommend consulting a damp specialist or building pathologist, such as Hutton + Rostron. These are independent consultants that will provide a professional opinion and are not ‘damp-proofing’ companies whose mandate it is to sell you their product.
Our home definitely has some damp issues that need managing; when we first moved in the wallpaper was so moist it was literally dropping off the walls and there was a musty smell in the air.
Mabel’s walls were showing signs of serious damp.
The main cause of damp in the house is the lack of habitation and heating, in conjunction with the lack of ventilation. On the ground floor, one of the causes of the damp is the fact that one side of the house is slightly buried. This is causing damp to penetrate sideways from the surrounding earth.
Previous owners have already attempted to remedy this by removing the original lime plaster and ‘tanking’ the first three feet of the ground floor walls with cementitious material. This hasn’t worked, and this later alteration is either failing or in some places has actually blown. In the lounge, there is a damp vertical section of wall where we believe the downpipe on the external leaf has failed in the past and the wall is taking time to ‘dry out’.
In addition, there is also a build-up of hygroscopic salts on the dividing wall between the kitchen and lean-to.
However, nearly a year after buying the house, the moisture level in the air has reduced, the musty smell has gone and the building feels much drier — illustrating that we have at least got some of the issues that caused the damp under control.