Underground Pool Design
If a big garden is available for the installation of an indoor swimming pool and there are no planning issues an underground pool would probably be a more expensive option. On the other hand if garden space is limited or a view is being obstructed or if there are planning constraints, an underground pool may be a viable option. Construction costs will often be surprisingly low but only if there is somewhere local to dispose of the excavation arisings.
Indoor Design ConsiderationsUnderground Pool Considerations
Providing natural light in a basement pool is very difficult and is therefore one of their main disadvantages. In an underground pool, this can be provided by a light well that can be covered by a grid to be safely walked on at garden level. A light well at each end of the underground pool can provide a surprisingly large amount of pleasant natural lighting without any glare. The waste air and fresh air inlets from the AHU can be connected to the light well. Every lightwell will need to be provided with a sump and submersible pump, connected to a soakaway, to dispose of rainwater.
If an Undercroft is included, the depth of excavation for an underground pool will be at least 4m. This implies that there will need to be at least 5-6m space between the edge of the excavation and any footings of adjacent buildings.
This will not be possible in many gardens and so the excavation will need to be done inside permanent sheet piling that will need large heavy equipment for installation and safe access for these may be impossible to provide. ICF walls can then be provided inside the sheet piling to provide the wall finish and keep the heat in.
The roof structure can consist of beam and block with screed and an Alkorplan membrane protected by more screed.
This can be covered in sedum grass roofing that only requires about 100mm of depth. Conventional topsoil and turfing will require at least 300mm.