Do I need building regulations approval for a new bathroom?

If you are simply replacing a bath with a new bath and swapping taps, you generally do not need building regulations approval. However, the moment you add or move electrical fittings in a bathroom — a new extractor fan, a heated towel rail on a spur, or downlights — the electrical work must comply with Part P of the Building Regulations. The easiest route is to use a Part P registered electrician who can self-certify the work. If your electrician is not registered, you will need to apply to building control separately.

Drainage changes are the other trigger. If you are adding a new bathroom where one did not exist before — for example converting a bedroom into an en suite — you are altering the drainage system and that requires a building regulations application. The soil pipe routing, fall gradients, and ventilation all need to meet the standards. I always recommend clients budget around £300 to £500 for the building control fees because trying to avoid it causes much bigger problems when you sell the property and cannot produce a completion certificate.

Ventilation is another requirement people overlook. Building regulations state that a bathroom without an openable window must have mechanical ventilation — typically an extractor fan rated at fifteen litres per second. Even if you have a window, adding an extractor fan is good practice to prevent condensation and mould. If structural work is involved, such as removing a wall to enlarge the bathroom, that obviously needs building control sign-off as well. In short, most bathroom refits involve at least one element that requires approval.