Why waterproofing (tanking) matters
Tanking is a waterproof membrane applied behind tiles, particularly around showers and baths, to stop water getting into the wall or floor structure below. Skipping this step is a common cause of hidden damp and rot that only becomes visible years later — worth confirming it's included, not assumed, in a refit quote.
KBSA and TrustMark, what they actually mean
The KBSA (Kitchen Bathroom Bedroom Specialists Association) is the main UK trade body for the sector, though membership is limited to a few hundred companies nationally, so it's not something every bathroom fitter will have. TrustMark is a broader government-endorsed scheme covering many trades — worth asking which, if either, your fitter holds, rather than assuming either is universal.
How long does a bathroom refit take?
A fixture swap (like-for-like toilet or basin) is usually a day or two. A full bathroom refit including tiling and waterproofing commonly takes 1-2 weeks, and it's often the only bathroom in the property out of use for that period — worth planning around if you only have one.
Walk-in showers and wet rooms, what's different
A walk-in shower needs careful floor falls (gradient) toward the drain to work without a shower tray — this is more technically demanding than fitting a standard shower tray and enclosure, and a poorly built one is a common source of water pooling or leaks. A full wet room takes this further, tanking the whole floor.
What affects the cost
Cost depends on whether pipework and electrics need moving (not just swapping fixtures in place), the tiling area, fixture quality, and whether structural changes are needed (like removing a bath for a walk-in shower). Moving a toilet's position, in particular, is one of the more expensive changes because of the soil pipe work involved.
Planning bathroom storage during a refit
Built-in storage (vanity units, recessed cabinets) is far easier to plan during a full refit than to retrofit afterwards, since it often needs coordinating with tiling and plumbing runs. Worth deciding on storage needs before the layout is finalised, not after tiling is complete.
Understanding the labour vs materials split
Tiles, the suite, and fittings are often a smaller share of the total cost than labour, particularly for a full refit involving tanking and tiling. A cheap quote is worth checking against the same fixture brands and tile spec as competing quotes, not just a lower labour rate.
Bathroom plumbing work and WaterSafe
Moving or adding plumbing (a new shower, relocated toilet) should follow Water Fittings Regulations, the same rules a WaterSafe-registered plumber works to. If your bathroom fitter isn't a registered plumber themselves, ask who does the plumbing side and whether they're WaterSafe registered.