Our approach is to always look at the big picture, that is to find the cause of a problem and not to just treat its symptom. For instance, almost every job we work on will have a few simple issues on it, these are usually very minor such as poor maintenance of guttering, drainage, capping stones and sills etc, or poorly executed detailing by the work of the previous builders. Perhaps the largest factors affecting internal damp issues are always external problems such as concrete paths being higher than the internal floors sometimes even slopping toward the house, brick vents that are supposed to vent suspended floors being covered up, no ground drainage, or hardstanding (concrete floors, stone slabs, tarmac etc) butting against the walls and collecting water.
The reality of the situation is that most modern materials just aren't suited for old buildings, they are fantastic materials that offer substantial protection to a huge variety of buildings. But the concept of 'eradicating damp' by covering floors in plastic and concrete barely serves to mask the problem and it does nothing else but hide the effect of whatever is causing the problem. This process is like putting on a rubber glove to put your hand in water, whilst your hand is technically impervious to the water, the fact remains that the water is still there. Over time, water will degrade cementitous materials and continue to cause damp, albeit in a weeks, months or years. One property we worked on had a cement render applied 5 times over a ten year period, each time it cracked and continued to track water through and cause severe damp issues on the inside. So whilst lime and its overall process may be more expensive, it should last the time of the building if appropriately maintained.
There is a lot of information out there about the negative effects that modern materials have on old buildings, including the use of cementitious materials, the 'myth' of rising damp and the most devastating of them all cavity wall insulation.
For further reading please try the following;
LIME AND BUILDINGS
A huge proportion of homes in the UK were built pre 1919, meaning they were built of :
This means that the vast majority of us live in a home that was designed to embrace, or at the very least 'cope' with, moisture and work with it by allowing any excess moisture to evaporate whenever necessary. Issues arise when old buildings are combined with modern materials and methods, applied by tradesmen that lack the required knowledge. Cementitous materials, fibre glass insulations, plastic paints, and damp proof membranes do not manage moisture, they trap it...or at the very best, hide it! Cement is a brilliantly versatile product, with immense structural capabilities, therefore displaying the opposite characteristics of even the strongest of hydraulic limes. Why then would we expect them to work on a building that is constantly moving and breathing? The rigid cement renders and pointing inevitably crack, which allows water to penetrate the walls through capillary reaction, trapping the moisture within the walls with no means of drying out.
By simply acknowledging the differences in the materials use to build your home and the materials that can and probably have been applied to your home in recent years, we can begin to appreciate that the two are not compatible.
By simply removing a cement render or pointing, its possible to see a home drying out on a daily basis both inside and out! then it is time to dress the home in the clothes it needs. The heritage approach is to analyse the needs and requirements of a building and treat it accordingly, that is to not treat every building the same, use exactly the same mixes regardless. But to have an understanding of some simple building principles and apply them!
Ideally any building built using traditional methods should have;
If all four of these steps are put in place it is unlikely that any damp problems will arise, but obviously every situation is different and there may be many other causes, especially with roofing, chimney issues etc.
Understanding the lime building approach can be a very confusing concept, which i hope to shed some light on in this brief, but hopefully succinct insight in to lime.
All the information on this page boils down to one simple principle, if your property was built using lime or earth mortars then all materials used in its repair should be compatible with it. This means that you can rule out almost all modern materials and systems, such as a cement renders and concrete floors, plasterboards, kingspan and rockwool insulation systems, tanking and damp proof membranes etc as none of these are designed to be compatible with a building that can 'breathe'. All the Aforementioned materials trap moisture within the structure of the walls and increase any damp problems as can be seen in the diagram below (diagram courtesy of Ty Mawr Lime).