Bathroom waterproofing before tiling: what homeowners should check
Why tiles and grout are not the waterproof layer and what to agree before a shower is tiled.
Applies to: UK homeowners; shower and wet-room construction varies by system and property.
Last checked: 16 October 2026
Key points
• Tile finishes and grout are not a substitute for a correctly specified waterproofing system.
• Agree the shower base, junctions, penetrations and waterproofing responsibility before tiling.
• Ask for product details and photographs of concealed waterproofing before it is covered.
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Why it matters
Water can reach the structure through cracked grout, movement joints or faulty junctions. The waterproofing detail underneath the tiles matters more than an attractive tile finish.
Checklist before you start
• Confirm whether the shower, bath surround or wet room needs a waterproofing system.
• Agree who prepares the substrate and checks movement or deflection.
• Ask which membrane or tanking system will be used and whether components are compatible.
• Record pipe penetrations, corners, tray junctions and curing periods in the scope.
What to do next
Before covering the area, request photos of the completed waterproofing and a clear handover note. Keep maintenance instructions, especially for silicone and movement joints.
Official sources
Use these official sources for the current detail that applies to your job, contract or location.
BuildPair provides general information and signposting, not legal, structural, electrical, gas or building-control approval. Requirements can change and the right answer depends on the work, contract, location and facts.
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