Solving damp issues in historic buildings
Solving damp in period properties requires a thorough understanding of old buildings, the wide variety of materials used in them and the way all of these work, both independently and collectively.
Damp problems can be caused by something as simple as a blocked downpipe or a missing tile. However, they can also be a sign of something more serious such as cracked cement render or pointing trapping water in the walls, or external ground levels being higher than internal floors, which creates severe damp in the ground floor rooms. It is essential to understand and address the cause of the damp issues, both for the structure of the building and for your own health, as mould growth in damp properties can be very harmful.
It is worth mentioning here that regardless of what some people (who do not specialise in older properties) may tell you, it is impossible for a damp proof course to work in an old building. This is because the very nature of an older property is that it has an intimate relationship with its environment, including moisture, whereas modern techniques (including a damp proof course) are quite the opposite, being focused on sealing and isolation. Old properties are specifically designed to allow moisture to pass through them and any attempt at introducing a damp barrier of any kind only increases the probability of trapping damp in the first place.
Replacing cement renders and pointing with lime will allow the walls to dry out over time, although it can take months or even years to dry completely. Removing paints made from plastic, non-permeable materials from the internal and external walls of a building can also help the walls to dry. Meanwhile, installing 'French Drains' can also alleviate water pressure on the base of the walls, creating a cavity into which the water can drain.