Basement Swimming Pool Construction in Kent

Discover the basement construction process we went through to build a sauna, underground gym, and most of all a stunning swimming pool below an existing house located in Kent.

Basement Swimming Pool and Leisure Complex

The basement swimming pool project in Kent houses a basement sauna, underground gym, and most of all a stunning swimming pool. The swimming pool was almost the full width of what was a massive basement construction! Amazing ancient Woodlands surround the grounds. To get some of the best views of Kent countrysides, the basement includes several floor-to-ceiling glazing.

The green roof construction hides the underground gym and swimming pool blending it into its surroundings. Basement tanking and waterproofing ensures the longevity of the space. We strive to lead the basement construction industry in basement waterproofing. MJ Rooney is a safe contractor with decades of experience. We brought along these credentials and provided one of our most modern spaces full of excess and style.

Digger installing sheet piled earthwork support for basement construction

Groundworks

The groundworks for the basement swimming pool has three main factors that affect the design:

  • The proximity of the existing house and a protected tree to the excavation

  • The hillside that the footprint of the basement sits within

  • The sheer size of the underground gym and the swimming pool space

Drive steel sheet piles into the ground to provide earthworks support. Excavate down two meters and use a steel wailer to support the sheet piles. This system allows the construction industry to dig down without disturbing surrounding structures. Being a safe contractor, we assured to track every step of the basement excavation.

The construction industry treats groundworks with the utmost respect. Our training and experience in groundworks will always provide safety during basement excavations.

Formwork

The excavation of the basement swimming pool to the depth of the huge props will reveal the sheet piles and the ground support system. Next, we lay the bentonite geotextile matting over all its surfaces as the first layer of the basement waterproofing.

 The reinforcement bars are the skeleton of any concrete construction. They not only enable the concrete to take huge stresses but also stop concrete cracking during its curing process. This reduces the passages for water to pass through the basement finishes. This adds to the basement waterproofing to protect the concrete construction. Workers will pour the concrete when the reinforcement is in place.

 

Steel erection gang installing beams for a basement swimming pool roof structure.

Concrete Construction

The concrete poured on the base of the swimming pool needs to be consistent. Watery concrete would have never allowed us to create the finish to pool base that we wanted. 

Concrete construction needs to be sequenced. It will ensure that the shuttering can be propped against solid concrete surfaces. The concrete slab will support the wall shuttering after the base is done. Planning concrete construction in this way ensures a safe construction sequence. Remove all shuttering and supports after leaving the concrete to cure. Now we have a concrete box with completely structural sound and very impressive to look at. It’s now perfect for an underground gym, basement sauna, basement swimming pool. This basement houses all three!! 

Green Roof Construction

Now, green roof construction may be a bit of an understatement for this project. The clients originally wanted a pitch and put a golf course on top of the basement! That gives you an idea of what was needed structurally. They needed a massive basement space with no internal walls that could hold a golf course!

The first thing to install was the steel structure to withstand such pressures. The steels sat on the back wall of the basement and on a steel frame at the front. The steelwork at the front of the basement swimming pool was there to allow floor-to-ceiling glazing. Well-designed and engineered steelwork is easy to erect compared to other methods and moved the build on to the next phase of concrete.

The formwork for the slabs consists of a timber deck supported by steel props down to the basement floor. By pouring concrete within the webs of the steels, we constructed all the sides of the basement. Once the concrete gets cured, the whole structure will get very solid and rigid. The framework needs the support of the whole structure.

Installing bentonite waterproofing for swimming pool in excavation by construction workers

Waterproofing

We used two systems to waterproof the basement. First, we wrapped the concrete formwork in a bentonite geotextile. Then we bonded the geotextile completely to the surface once the concrete had cured. If there were any water that reached the waterproof membrane, the bentonite would swell thus blocking its passage through. It is an active basement tanking system. On the inside of the basement, we used a cavity drainage membrane to all walls and floors. If water got through the concrete it would travel behind the cavity drainage membrane into a drainage channel. The channels go to a drainage pipe that goes out into the hillside woodland area to drain. So if the basement ever leaked, water would never come in contact with the internal finishes. The reason we used a drainage membrane instead of a basement tanking system is it guarantees the water won’t build up pressure and get through.

The slab above needed a seamless waterproof membrane. This was done with FIS Epocote MMA which is a liquid applied waterproof membrane. We painted it over the concrete and the steels to avoid all water passages into the basement swimming pool. After testing the waterproof membrane, we laid out a drainage membrane. This will prevent water could build up. The basement swimming pool at that point was completely water-tight and ready for finish.

Why have a basement swimming pool?

Basement swimming pools are weatherproof! No matter what time of year, day or month, your basement swimming pool environment will be summer. Add massive glazed windows as with the project above and you may as well be outside. No wind, no rain, no sunburn, no off-season!!

Basement swimming pools are in your house! You could live in a townhouse in the center of London and have a swimming pool! Have an underground gym? Why not include a swim in your workout? The fact is a basement swimming pool gives you privacy and convenience. But most of all it gives you access to a swimming pool wherever you live!

People use basement swimming pools! An outdoor swimming pool runs the risk of becoming a very expensive ornament. It’s going to be a hit with the kids in the summer and you’re going to be looking at a sea of leaves in the winter. Consider every bath or shower you have precluded with a quick dip in the pool! Bored children? Throw them in the pool!

Aside from adding value to your property a basement swimming pool will add value to your time. Be it with your family or for your own personal health. A space like this will inevitably change your daily life and give you the impetus to improve.

Check the wine cellar that we constructed in a basement below a Grand Manor House located in the heart of the Kent countrysides.

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