Basement Waterproofing & Tanking
Basement flooding is a worry you don’t want to have, but when you do, you want it fixing quickly. In London, flooding is a risk for homeowners and businesses. The increase in heavy rainfall means that London basements and cellars are flooding more often.
Basements will almost always be damp because of the way they are made. Moisture present in the ground penetrates through the walls and floors of cellars and basements. Flooding occurs when water in the ground builds up against the structure, creating hydrostatic pressure. The groundwater level can increase because of heavy rainfall, location of the property near watercourses, construction of nearby basements, or a burst water main. You might only see a small amount of water enter your basement during flooding, but you may find that water can enter your cellar quickly in a short space of time.
Whether you have just moved into a London home or your long-term residence is experiencing more flooding problems, it can be treated. With the right waterproofing system in place, you can make basement flooding a thing of the past.
Clay based soils present a high risk of ground water flooding.
As water percolates into the ground, it doesn’t drain away freely, sitting against the structure.
The resulting hydrostatic pressure exploits weaknesses in the structure, causing the basement to flood.
Waterproofing Your Basement
Basement waterproofing can be done in different ways, depending on your needs. The appropriate waterproofing system will be installed based on whether you want to use your basement for dry storage or you want to convert it into another room.
If you want to waterproof your basement, you should get a CSSW qualified surveyor to complete it for you. Waterproofing of below ground structures, including basements and cellars, is covered by the code of practice BS8102:2022. The design of your waterproofing system will consider:
- The proposed use of the basement
- Accessibility for maintenance
- Suitability of the chosen method for the structure
Which Basement Waterproofing Method Is Right For You?
The code of practice states that the risk of flooding should be assumed at some point during the life of the structure, so you can feel rest assured that your basement is protected if you take the necessary steps. BS8102:2022 provides two methods for waterproofing an existing cellar or basement.
Type A Barrier System (Tanking)
The Type A barrier system, better known as tanking, is when a waterproof render or tanking slurry is applied to the walls and floors of a basement or cellar area. This acts as a barrier between your home and the water, keeping water out of your property.
It sounds like the perfect solution, but it might not be right for your home. Tanking relies on obtaining a good bond to the substrate. With many existing basements and cellars constructed of brick, the preparation required can often mean the use of grit blasting or bush hammering, which can create a lot of dust and debris. If a good bond is not obtained, then the risk of failure is increased especially when the tanking render is subjected to hydrostatic pressure. There is also a risk of movement causing cracking of render coats and failure.
If you want to add fixtures and fittings to your London basement or cellar, this can cause more problems with the tanking method. Penetrating the render can lead to dampness or even flooding, which would invalidate your warranty and put your property at risk. If you aren’t sure whether basement tanking is right for you, contact us for a free survey.
Failed tanking render in a vault.
Type C Cavity Drainage Membrane
The most popular method for waterproofing basements and cellars is the Type C cavity drainage system. This is the industry standard and the most reliable system you can get for your home. A polymer studded membrane is installed and applied to the walls and floor. Using drainage channels around the perimeter, it leads to either a sump and pump or existing drainage systems. By managing the water entering the basement, you won’t have to worry about additional stresses induced within the structure from hydrostatic pressure.
Anyone hoping to modify their basement or cellar space after waterproofing will find that the Type C system makes it easier to add fixtures. A dry lined wall can be installed onto the cavity drainage membrane, allowing the addition of electrical outlets, shelving, and other fixtures easily and without compromising the seal.
Unlike the Type A method, there is little to no preparation needed, meaning that the new cavity drain system can be installed with minimal disruption to your home. You can start using your new space in no time.
Cavity drainage system installed to a vault, ready for dry lining.
Cavity drain membrane installed to basement flats
Find CSSW Qualified Surveyors in London
BS8102:2022 states that a CSSW qualified surveyor has to be involved in the design team to ensure correct waterproofing system design in a new basement construction. We have experience in waterproofing London basements, as we have designed and installed a number throughout the city, from new builds to renovations. Throughout the construction process, our surveyors will be there for you. If you have any questions or there are potential issues while waterproofing your London cellar, they will let you know and help you find the right solution.
Warranty providers often have extremely strict requirements when it comes to basement waterproofing. For new builds, two forms of waterproofing are needed by providers such as CRL, LABC, and NHBC. Our CSSW qualified surveyors can advise you on the best options for your home and ensure any waterproofing meets both regulatory and warranty requirements.
Get Your Free Survey Now
At London Waterproofing Solutions, we will carry out a free survey of your basement to understand your requirements and design the right waterproofing system for you. Your fully qualified CSSW surveyor will carry out the survey and be your point of contact throughout the work.
You’ll receive a detailed report after the survey, and when you decide to go ahead with the London waterproofing installation, our team of qualified technicians will be there for you. When the work is completed, your lead technician, Project Manager and/or surveyor will sign off the work and provide you with a 10-year guarantee for the property and a system manual. For a small additional fee, our standard guarantee can be underwritten by Guarantee Protection Insurance, for added peace of mind. The cost of the insured guarantee is based on the value of the contract and will be confirmed with your initial quotation.
You can book your free survey now. Call 020 3794 4200 or fill in our contact form.
10 Year Guarantee
On completion of the installation, we will issue you with a 10 year guarantee. Our guarantees are issued for the property making it simple to transfer in the event of a sale. We do not charge for updating guarantee information with a new homeowner.
For a small additional fee, our standard guarantee can be underwritten by Guarantee Protection Insurance for your peace of mind. The cost of the insured guarantee is based on the value of the contract and will be confirmed with your initial quotation.
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Frequently Asked Questions
Why is my basement flooding?
Basement leaks can be caused by a number of factors. The most common causes include groundwater flooding, poor drainage, and construction of nearby basement properties. Basements are prone to flooding so you’ll need to waterproof your cellar to prevent flooding. Groundwater flooding is especially common in London.
Is a groundwater flooded basement dangerous?
Groundwater flooding may not seem dangerous, but it can be, particularly if you have electrics installed at low levels. It can cause water damage to your property as well as potentially destroying your belongings. You should also avoid walking through the flooded area until gas and electric services have been disconnected, as you may be at risk if you don’t. In some properties, the gas and electric mains supply are located in the basement, therefore if you are in any doubt contact a professional for assistance.
What should I do if groundwater floods my basement?
When you discover a basement flood as a result of groundwater, you’ll want to act quickly, as it can occur after significant periods of rainfall. If the water presents a risk to electrics or gas within the area then these should be isolated. The next step is to remove the water. You may be able to hire a pump to discharge the water, however, if you are unsure then contact a professional to assist you.
Will my London basement flood?
When it comes to a basement flood as a result of groundwater, London is susceptible because the clay-based soil can create perched water tables, but there is also the Thames tide, heavy rainfall, underground streams and the drainage systems to consider. According to the Environment Agency, your home may be more likely to flood if you live in the Hammersmith, Fulham, Southwark and Wandsworth areas of London.
Is groundwater flooding covered by insurance?
Most home insurance providers do not cover groundwater flooding in their home insurance policies, which is why it is so important to ensure basement waterproofing or tanking solutions are in place to protect your property.
Can I get rid of groundwater from my basement?
Groundwater can be an ever-present threat to your home, especially if you live in the London area. There are a few ways to reduce this risk, such as installing a moisture barrier or a cavity drainage membrane. This helps to manage the water entering your home.
