CareHomeDeskCareHomeDeskLiquid membrane, sheet membrane or proprietary former -- what each system requires and the standards that apply.
There is no single British Standard that covers all wet room waterproofing systems, but the workmanship standard for plastering and screeding (BS 8000-0) applies to substrate preparation, and product standards such as BS EN 14891 cover liquid-applied waterproof products used beneath tiles. NHBC Standards Chapter 7.2 provides useful specification guidance for floor waterproofing in wet rooms, and the British Board of Agrment (BBA) certificates for proprietary tanking systems set out the specific conditions under which those systems are warranted.
These are brush or roller-applied products -- typically polyurethane, polyester or cementitious -- that cure to form a continuous waterproof layer. They are the most common choice in care home conversions because they can be applied to existing substrates and are relatively fast. Key requirements: the substrate must be sound, clean and dust-free; all movement joints must be bridged with reinforcing tape bedded into the first coat; all penetrations must be sealed with proprietary collars; minimum 48-hour cure before tiling. Follow the manufacturer's coverage rate -- under-application is the most common cause of premature failure. Inspect before the first tile goes down.
Sheet-applied systems -- typically polyethylene bonded to a fleece carrier -- are bonded to the substrate using the manufacturer's adhesive mortar. They offer consistent thickness and are faster to apply on flat substrates. They are less tolerant of substrate imperfections and require more careful detailing at junctions. They are well suited to concrete floors where a high-performance waterproofing layer is required under a tile bed. Used correctly they tend to be more reliable than liquid systems on large floor areas, but only where the installer is trained and familiar with the system.
Pre-formed polystyrene or foam formers with integrated drainage and pre-formed falls are increasingly used in care home wet rooms. They are installed directly onto the structural floor (timber or concrete), often without a screed, and reduce the programme time significantly. They are supplied with compatible liquid waterproofing membranes. The limitation is that they are sized to standard room configurations -- bespoke rooms may require cutting, which can compromise the pre-formed fall. Ensure the former supplier provides a test certificate confirming the tanking system applied to their former meets BS EN 14891.
Waterproofing warranties in wet rooms are only valid when the complete system -- substrate preparation, membrane, installation, tile adhesive and tile/finish -- is supplied or approved by one manufacturer. Using a competitor's adhesive over a proprietary membrane, for example, typically voids the warranty. As the client, you should require the contractor to provide: the manufacturer's product data sheets, evidence of installer training for the specific system, and a signed warranty certificate on completion. A wet room leak can cause significant structural damage and puts residents at risk -- the warranty is your recourse if the system fails within its design life.
CareHomeDesk gives you compliance checklists, maintenance logs, and contractor management tools built around exactly this kind of knowledge.