CareHomeDeskCareHomeDeskGetting the fall gradient and drainage point wrong is one of the most common and expensive wet room defects -- here is what a compliant specification actually requires.
A wet room floor finish -- the slip-resistant vinyl or tile -- only performs correctly if the substrate beneath it is formed with the correct fall to drainage. Standing water on a poorly falled wet room floor is both a slip hazard in its own right and accelerates wear on the floor finish and any sealant joints. The fall must be built into the screed or a preformed shower former before the floor finish is applied -- it cannot be corrected afterward without lifting the finish.
General UK good practice for wet room floors specifies a minimum fall of 1:80 towards the drainage point, with some guidance recommending up to 1:40 for larger open wet room areas to ensure water clears reliably rather than pooling at the edges of the fall zone. Building Regulations Part H covers drainage generally but does not itself set a specific wet-room fall gradient -- the manufacturer installation instructions for the specific tanking or shower-former system being used should be treated as the primary specification, cross-checked against general good-practice guidance rather than assumed.
The drainage gully itself should be selected and installed to BS EN 1253 (gullies for buildings), sized for the expected water flow rate from the shower fitting being used. A point drain (a single central gully) is the traditional approach; a linear drain (a channel drain, often set at the wall or the room low edge) is increasingly specified in care homes because it allows a larger, more consistent fall across the whole floor without a dip in the middle of the walking area -- an accessibility advantage under BS 8300-2 for residents using a wheeled shower chair or walking frame.
The most common wet room drainage defect is a flat spot or reverse fall somewhere in the floor, usually caused by an uneven screed base not being checked before the shower former or tanking was installed. This presents as standing water some distance from the gully rather than at it, and is often blamed on the floor finish or the gully itself rather than correctly traced back to the substrate fall. If a wet room floor is not draining fully after installation, investigate the actual fall with a spirit level or laser level across the full floor area before assuming the gully is blocked or undersized.
CareHomeDesk gives you compliance checklists, maintenance logs, and contractor management tools built around exactly this kind of knowledge.