What is the minimum size for an en-suite?
About 1.2m × 2.1m — roughly 2.5m² — is the comfortable minimum for a shower, basin and WC. Building regulations set no minimum room size; they govern ventilation, drainage and electrics instead. Below 2.5m² it is possible with sliding doors and compact fittings, but every centimetre must be designed.
The 2.5m² en-suite works because each zone takes its minimum: an 800×800 shower, a 400mm cloakroom-depth basin, a short-projection WC with 600mm of standing room, and a sliding door that steals no floor. That is a genuinely usable daily shower room — most hotel en-suites are barely bigger.
What decides feasibility is rarely the floor area anyway — it is drainage (how far to the soil stack, covered at survey before any drawing) and ventilation (internal rooms need ducted extraction). A generous corner of a bedroom on the wrong side of the house is a worse en-suite candidate than a tight alcove sitting over the existing bathroom.
The resale arithmetic worth knowing before carving up a bedroom: an en-suite off the main bedroom adds appeal almost everywhere in our patch, but a double bedroom demoted to a single by losing 2.5m² can cost more value than the en-suite adds. Where the numbers are marginal we say so — a brilliant family bathroom beats a cramped en-suite plus a compromised bedroom.
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