We imagine that older properties become damp due to the wear and tear that they undergo over the years – and that is absolutely true. However, it is a myth that older houses have always been damp. In fact, in pre-20th century construction, the materials that were used tended to be breathable. These were stone, timber, lime-based plasters, and mortars – all materials that allowed the building to breathe and regulate itself with regard to damp and condensation.
It was only in later years, when more modern materials such as plastic membranes, fibreglass, polyurethane sheets, and gypsum plaster were introduced for remedial work in these buildings, that problems really started to occur.
Due to the fact that these materials prevented the original bricks or stones from breathing, what happened was that they actually trapped the damp in the bricks and stones. The damp, which usually travelled through in gas format, then turned to liquid and what we understand as serious damp issues took root.
If you are considering how to treat damp in an old house, you need to take into account several things.
What are the original materials that were used to build the house? If you are eco-conscious and want to follow the most environmentally friendly way of restoring an older property, you need to study how they were originally built. Traditional materials understood the need to breathe, settle, and work at one with the environment.
Avoid covering up the property with modern materials containing non-porous elements. Modern cladding on older properties did massive damage in the sixties and seventies. It’d be best to strip this down and go back to the original infrastructure.
To avoid damp in old houses and the onset of condensation, try and maintain a constant temperature of a minimum of 15 degrees. 15 degrees centigrade is the ideal temperature to avoid the build-up of condensation within the fabric of the building, which can lead to the overall structure becoming saturated. This is when serious damage occurs.
Despite the increasing call we hear in the mainstream media about insulating our homes, this can actually lead to greater instances of condensation. By trapping the heat in the older property, you are again stopping the building’s ability to breathe. That means that all that warm air is circulating in the house until it hits a cold wall, where it liquefies into condensation. If you are going to insulate, then you have to make sure you have adequate ventilation as well. This might necessitate additional expense – for example, modern PVCu windows are now fitted with trickle vents to help maintain surface temperatures above dewpoint.
If you really want to get into sourcing better insulation materials, you could look at using more traditional materials such as sheep wool or hemp fibres.
When redecorating, avoid using modern plastic paints. Materials such as lime mortars and lime plasters, clay and linseed paints are all carbon neutral – perfect for those seeking an eco-friendlier approach.
Take a tour of the area that surrounds the property to assess the amount of vegetation and soil that might be pressing up against the building. Strip back any artificial or non-porous materials that have been attached to the foot of the building. In short, your external walls now need to be able to breathe as they were originally intended to do so.
Check all the guttering and downpipes. Some damp may simply be the result of some blocked or broken guttering that, once fixed, will soon dry out.
Properties that have exterior ground levels higher than the inside may be at particular risk of damp or water ingress. Over the years, shifting foundations may have caused cracks that allow groundwater to seep into basements and cause flooding. This issue will need specialist care, probably through basement tanking, a system that creates a system whereby any water ingress is redirected to a collection point and then pumped back outside into a drain.
Basement tanking is particularly suitable for tackling damp in old houses. Because you are literally creating a ‘tank’, the original structure of the building remains undamaged, with any excess water encouraged into perimeter channels.
If you are renovating an older property and need to get a better insight into how to best protect your building against damp, Garratts Damp and Timber offer free surveys. Contact the company to book a visit.