Refitting a bathroom
If you’re simply replacing units and fittings like for like, you won’t normally need building control approval.
However, if you’re modifying the existing layout by removing walls, installing a separate shower or extending wash basin, shower or bath waste pipe runs, for instance, you will need approval.
If you’re replacing a lightweight steel or acrylic bath with a heavy cast iron bath, then floor strengthening may become necessary and in that case you will need to make a building regulations application. If in doubt speak to your local authority building control team (use the postcode search above to find contact details).
Any electrical work in a bathroom must be carried out by a qualified electrician, with the work either checked by building control or certified by the electrician if they’re a member of a Competent Person scheme.
If a new gas fitting, boiler or electrical circuit is to be installed, then you can either involve your local building control department or search for a Competent Person who’s registered to self-certify the work.
Change of use or adding a new bathroom
If you’re changing the use of a room to build a bathroom – for example in a former bedroom or storage area, then you'll need building control approval for any new drainage, waste pipes and extract ventilation, and for any structural alterations you may want to make.
The extra load imposed on the floor by the weight of a bath full of water will also need to be considered.
(Find contact details for your local building control department above.)
N.B. there's a requirement in new homes that a TMV (thermostatic mixing valve) should be fitted to a bath so that hot water can be limited to a maximum temperature of 48 degrees centigrade. Although this isn't a requirement in existing dwellings you should consider having one fitted to prevent scalds.