Bathroom renovation glossary
Plain-English definitions of 15 plumbing, waterproofing, tiling and accessibility terms that appear on bathroom quotes.
Free, no obligation. One local company prices it, not five.
15 bathroom terms explained
- Tanking membrane
- A waterproof liquid coating or sheet membrane applied to shower walls and wet room floors before tiling so moisture cannot reach joists or plasterboard.
- Shower former (wet room tray)
- A pre-sloped, waterproof floor board set flush into timber joists or concrete screed to create a level-access wet room drain fall.
- Low-profile shower tray
- A slim stone-resin or acrylic tray, typically 25 to 45 mm high, used for walk-in showers where a recessed wet room floor is not needed.
- First fix
- The stage after strip-out when hot and cold supply pipes, waste runs, concealed cistern frames and electrical cables are put in place before boarding and tiling.
- Second fix
- The stage after tiling is finished when the toilet, basin, vanity unit, shower screen, taps, lights, extractor fan and towel rail are fitted and connected.
- Soil stack (110 mm)
- The main large-diameter waste pipe that carries toilet discharge to the drain. Moving a toilet away from the soil stack adds plumbing work.
- Concealed cistern & wall-hung pan
- A toilet frame built inside a stud wall or furniture unit so only the pan and flush plate are visible, making a small floor easier to clean.
- Thermostatic mixer shower
- A shower valve that holds water temperature steady even if someone turns on a tap elsewhere in the house, required for safe accessible showers.
- Twin-impeller shower pump
- A booster pump fitted near the hot water cylinder in gravity-fed Irish houses to give strong, even pressure to a mixer or rainfall shower.
- Bathroom IP electrical zones
- Safety zones (Zone 0, Zone 1 and Zone 2) around baths and showers that set the water-resistance rating (such as IPX4 or IP65) required for lights and fans.
- Tile backer board
- Water-resistant cement or XPS foam board fixed to bathroom walls and floors in place of standard plasterboard in wet areas.
- Flexible S1 tile adhesive
- Cement-based adhesive formulated to handle slight movement on timber floors, backer boards and undertile heating mats without cracking.
- Anti-slip R-rating (R10 / R11)
- The slip-resistance grade of floor tiles; R10 or R11 matt porcelain is used on wet room and level-access shower floors.
- Comfort-height toilet
- A toilet pan around 450 to 480 mm high (about 50 mm higher than standard), making sitting down and standing up easier in accessible bathrooms.
- Occupational Therapist (OT) report
- An assessment setting out the level-access shower, grab rails or bathroom layout changes needed for a council Housing Adaptation Grant application.
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Questions people ask us
How much mess is there?
The room is stripped to the walls, so there's dust and a skip outside for a few days. A good company sheets the stairs and landing, cuts tiles outside where it can and tidies up every evening.
Is the work guaranteed?
Ask for it in writing: a guarantee on the workmanship, the makers' guarantees on the shower, the valve and the suite, and the guarantee on the tanking. The electrician gives you a completion certificate.

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