Building regulations approval isn't normally required for outdoor swimming pools.
The building regulations for outdoor swimming pools only stipulate that they must be unenclosed with no heated air surrounding the pool.
Any outdoor pool that has a permanent structure over it will become an indoor pool, but as long as the structure is unheated and unventilated it will not have to comply with building regulations.
Even though building regulations don’t apply to outdoor uncovered pools, you can still do your bit for the environment by ensuring the pool is properly insulated and installing a good quality cover to preserve the heat of the water.
You’ll save money on your pool running costs by doing this too, as your pool water will stay warmer for longer.
Building regulations do apply to indoor pools and the requirements are more involved than for an outdoor pool.
The floor and walls of the pool itself must be insulated in order to minimise heat loss into the ground. This heat loss should be reduced to 0.25W/m2/0C, which equates roughly to a pool heated to 28C and the ground with a temperature of approximately 10C.
Contact your building control team before starting work on the project.