Digging below ground level to make more space in our buildings is something that humans have done throughout history, from prehistoric times through to the Saxons who came to our shores after the Romans departed.
In more recent times many Victorian homes had basements or cellars for storing coal (amongst other things), and even today some Richmond homeowners maximise the space by excavating below the ground, not purely for storage but also to add extra living space in a new build. People are also catching onto the idea of renovating basements and cellars in older buildings to add space and value to their homes
Both residential and commercial properties situated in towns and cities are more likely to have a basement level as the cost of land is usually at a premium. So, buildings tend to extend upwards and downwards, with floors below street level beneath which are deep foundations. These spaces can have a wide range of uses, from lift shafts, shops, eating places or entertainment venues, to offices or even homes.
The trouble with digging into the ground is that there's sometimes a lot of water down there. The local water table will play a big part in this, as will seasonal rainfall and the efficiency of local drainage. And if a property is not adequately protected, then this water can cause a lot of problems.
Ground saturation can lead to something called hydrostatic pressure where water is forced through tiny cracks or porous walls. It can make its way through as water or vapour, and when temperatures drop it can freeze, which worsens the existing cracks. Broken downpipes and guttering, broken drains, substandard concrete with air pockets, soil erosion; these are all contributing factors to ground saturation that could affect your property.
The last thing you need is ground water seeping through the porous materials or cracks in basement walls and creating damp conditions that can lead to black mould, mildew, dry rot or wet rot, penetrating damp or rising damp. This is especially the case in buildings that contain wood anywhere within the structure, as the wood may rot, potentially causing structural damage which could be hazardous as well as costly to put right.
Signs that you have a damp problem include the obvious, such as visible cracks in the foundation walls, buckling walls (due to hydrostatic water pressure), white, powdery residue (known as efflorescence) on the floor or at the base of walls, and mould or fungus. It will probably smell damp and musty too, and may even cause respiratory problems with prolonged contact.
To avoid this problem, waterproofing and tanking is used to protect against water ingress. But what exactly does this mean and what does each process involve?
You might take a guess at this, as it's a familiar word. However, when it comes to basement waterproofing it refers to a collection of processes and materials used to stop water from gaining access.
Generally speaking, there are three methods of waterproofing:
Regulations surrounding the waterproofing of buildings is strictly controlled by BS8102:2009 'The British code of practice for the protection of below ground structures against water from the ground'.
In addition, property care services, preservation and damp proofing companies are governed by trading bodies such as the Property Care Association and the British Structural Waterproofing Association.
With these measures in place, you can be confident that any basement waterproofing solution you choose will be the best and most efficient, provided you employ a company that is registered with these organisations.
The method they use will depend on several factors, such as the local water table (whether it's low, high, or variable), the topography of the land around your premises, and even the intended use of the room (bathrooms, for instance, will require more consideration).
In some cases, a combination of these methods will be used to provide a permanent, effective solution to water ingress in your basement or cellar.
However, type C, known as 'Drained Protection', is by far the most widely used and is recommended by most property care services and waterproofing experts.
If you suspect that your basement or cellar space is suffering from a damp issue or you are planning a basement conversion, then your best course of action is to speak to a professional waterproofing company. In the latter case, incorporating the best waterproofing solution within the initial design and construction is the safest and most sensible way of avoiding future problems with damp. Retrospective solutions can be more problematic and more costly in a lot of cases, as they also require additional work to repair or restore damaged masonry, concrete and timber.
Although the three methods are the most commonly used, with type C being the most popular, a reputable waterproofing expert will survey your property and recommend a solution that suits your needs.