When it comes to our homes, we notice when things go wrong - whether it’s a leak or when something is broken. However, it can often be more difficult, if not impossible, to notice when bigger things go wrong.
That is why basement tanking is so important, especially in London. To give you an essential understanding of what basement tanking is and why it matters, we have put together an overview of the most important questions.
What is Basement Tanking/Waterproofing?
Basement tanking is essentially waterproofing your basement or cellar to ensure that it stays warm and dry, helping to keep it damp-proof and watertight. Damp and water can get into your basement and cellar easily when the structure is below external ground level and is unprotected without tanking/waterproofing. The ground bearing walls are at risk of hydrostatic pressure that is brought on by retaining groundwater coming to bear on the below ground structure.
Why is Basement Tanking Important?
While the basement or cellar of your home may not immediately seem like it is as much a part of your house as the above-ground areas, from a structural point of view it very much is. If water damages underground sections of the house, the overall structure could become unstable. Also, damp can move upwards through the house via capillary action. If water penetrates the basement level, it could very soon reach up to be causing problems elsewhere. As a result, it is much better to stop the problem at its source.
Why is Basement Tanking in London Particularly Important?
London has a set of unique situations and issues that make damp proofing a property as a whole more vital, and basement tanking, in particular, more essential.
- Soft Clay Soil - London’s geological underpinnings are much more water-permeable than many other cities. In fact, this is the major reason why it was not until after World War Two that we saw the large scale constructions of taller skyscrapers in the city. In contrast to a city like New York where the city is built on solid granite, London’s ground is much softer. This means that it is harder to build tall buildings without concrete, and easier for water to move through
- Building Proximity - with many of London’s buildings being tightly compacted and close together, damp problems tend to be contagious. With other more sparsely built-up areas, you tend to see gaps between the buildings which allows water to move more freely. This is the same kind of physical processes that makes the wind so much stronger when it is funnelled down between buildings
- Modern Building Practices - to build newer structures, as London often does, deeper excavations are often necessary to make sure all the essential features and connections are put into place. However, this has the effect of providing a greater displacement of the groundwater, causing the overall groundwater level to rise, meaning that more London basements are potentially vulnerable to damp
- Heavier Rainfall - although many commentators have been noting the overall lower levels of rainfall in the Southeastern corner of the UK, the effect is often that when the rain comes, it comes all at once. This means that groundwater experiences sudden sharp spikes, reaching elevations that it would not normally reach if the current weather cycles were more predictable
What are the Different Types of Basement Tanking?
There are two types of basement tanking which cover the needs of the vast majority of properties, as well as what is called a 'sealing' system. Here is an outline of the main essentials:
- Cementitious Tanking (Type A) – this is used in basements where a low level of movement is anticipated. It uses mutable coats of waterproof render to create a waterproof seal around the basement walls and floors. This type is often seen on coal vaults and cellars
- Membrane Sealed Tanking (Type C) – this system is employed in basements and cellars where higher or more unpredictable levels of water are expected to be faced. Allowing water to pass behind the membrane, the water is then dispersed into the perimeter channels that are directed into an alarmed sump and sump system
- Combined Systems - a combined system is where two or more tanking types are incorporated into a tanking/waterproofing design
- Ventilated Membrane System – this set of techniques is used in situations above ground where no free-running water is expected. A membrane will provide a dry internal surface that prevents both damp penetration and salt contamination
The exact procedures and techniques of basement tanking that your particular property will require depends on several different factors. These include, but are not limited to, the following:
- The intended usage - this is very important as it will dictate the design and type of the tanking/waterproofing used
- The approximate age of your property
- The soil and ground content in the immediate area
- The specific kind of basement you have
- The concentration of buildings in your location
There are several different kinds of basement, and each requires proper understanding before an effective basement tanking process can be considered.
- Underground Crawl Space - a very small type of basement. As the name implies, it cannot be stood up in, but a person can crawl down into it, and use the area for some limited storage. Often it would have been put in place as a barrier against invasion by rats
- Walk-Up Basement - a basement with an exterior entrance through a stairway. Usually, this type has basement doors that prevent penetrating damp caused by rainwater
- Look-Out Basement - a kind of basement that has been constructed atop a flat area where the basement walls reach above ground level with the windows letting light in from above ground
- Daylight Basement - a basement on a slope where a portion of the floor is above ground with a door to the outside. The area of the floor below ground level is the true basement space and is often fitted with ventilated windows and other aeration systems to prevent damp problems
- Fully Underground Cellar - this is usually a storage room that often contains wine or rarely used household items. Ventilation or other climate control systems are sometimes installed to keep the temperature and humidity level constant
Rather than waiting to find out what basement tanking can do, it’s always better to get a professional to evaluate the situation now before it gets any worse.
For more information or to enquire about our basement tanking services, please call our team today on 0208 535 7536 and we will be happy to help.