Waterproof flooring: what is genuinely waterproof and what is not

Water-resistant, waterproof and watertight

Water-resistant means the surface will survive a spill wiped up promptly. Most water-resistant laminates are rated for something like 24 hours of surface exposure, and that rating almost always excludes standing water and appliance leaks.

Waterproof means the material itself is unaffected by water. Vinyl and SPC planks are genuinely waterproof; you could submerge one indefinitely and it would be unchanged.

Watertight is the property that actually matters, and it describes the installed floor rather than the plank. A watertight floor does not let water through to the subfloor. That depends on the joints, the perimeter and the method of fixing — not on the plank's material.

The genuinely watertight options

Sheet vinyl is the most watertight domestic floor available. A single sheet in a small room has no joints at all, and where a seam is unavoidable it can be hot- or cold-welded into a continuous surface. Taken up the wall as a coved skirting, it forms a tanked floor of the kind used in wet rooms and commercial kitchens.

Glue-down LVT is the next best. It is fully bonded, so water cannot travel underneath, and the joints are tight. With a sealant bead at the perimeter and around pipe penetrations, it handles a domestic bathroom or kitchen leak comfortably.

Both of these are systems, not just materials — the watertightness comes from how they are fitted. A sheet vinyl loosely laid with an unsealed perimeter is far less protective than the same product properly bonded and sealed.

• Sheet vinyl, welded seams, coved edges: fully watertight — best for bathrooms and wet areas
• Glue-down LVT with sealed perimeter: excellent for kitchens, utility and bathrooms
• Click SPC: waterproof planks, but water passes through joints to the subfloor
• Water-resistant laminate: surface spills only, not for wet rooms

Where click floors fall short

Click SPC and WPC planks are waterproof, and the marketing leans hard on that. But a click floor is a floating floor with mechanical joints, and water finds those joints. It runs through, spreads across the subfloor underneath, and has nowhere to evaporate to because the floor above is impermeable.

The result is the failure we get called out to most often in bathrooms: no visible damage to the floor at all, but a musty smell, and a saturated chipboard or ply subfloor beneath. The planks themselves are perfectly fine — the system was never watertight.

Some manufacturers now supply a sealant for the click joints, and used properly it helps. But in a room with a shower, bath or washing machine, sheet vinyl or glue-down LVT is the correct specification and it is not much more expensive.

The fitting details that make a floor watertight

Perimeter sealing. Wherever the floor meets a wall, bath panel, shower tray or kitchen plinth, a flexible sealant bead stops water running down the gap. This is a ten-minute job and it is the single most valuable detail in the whole installation.

Pipe penetrations. Radiator pipes and waste pipes coming through the floor are the classic leak path. They should be cut tightly and sealed, not covered with a loose plastic pipe rose.

Doorway transitions. Water follows the threshold out of the bathroom and under the hall floor. A properly bedded threshold with sealant beneath contains it.

Coving in wet rooms. Where a shower is not enclosed in a tray, the floor covering must run up the wall by at least 100mm behind the tiling or capping. This is standard commercial practice and is the difference between a wet room and a wet ceiling downstairs.

Choosing by room

Bathroom with a shower over bath: sheet vinyl with sealed perimeter and coving, or glue-down LVT with a fully sealed perimeter. Never click flooring, and never laminate.

Downstairs cloakroom: sheet vinyl is cheap, quick and completely watertight in a room this size. LVT if the look matters more.

Kitchen and utility: glue-down LVT with a 0.55mm wear layer, sealed at the plinth line and behind the washing machine. This is the standard we specify most often.

Conservatory or garden room: glue-down LVT for its stability under temperature swings, with a moisture-tested slab and a DPM if readings require it.

Basement: moisture testing is mandatory. Any impermeable floor over a damp slab traps moisture, so a liquid DPM under the levelling compound is usually required before anything is laid.