Soudal Complete Wet Room Waterproof Tanking Kit

A waterproof tanking kit that actually includes everything you need is rarer than you’d think. Soudal have put together a genuinely complete system here: liquid membrane, deep-penetrating primer, and reinforcement tape all in one box, matched and designed to work together. Whether you’re tanking a shower enclosure, a full wet room floor and walls, or a bathroom that’s seen better days, this kit gives you a proper waterproof barrier beneath the tiles rather than relying on the tiles and grout to do a job they were never really designed for.

The main event is the Soudagum LM, a 4kg ready-to-use liquid waterproofing membrane. It goes on with a brush, roller, or trowel, dries in around 3 to 4 hours per coat, and cures to a flexible continuous film that stays permanently elastic. That flexibility matters more than it sounds. Buildings move. Substrates crack. A rigid membrane will bridge a hairline crack right up until it doesn’t, whereas an elastic one keeps working even when the substrate shifts slightly beneath it. Tile adhesive bonds directly to the cured membrane once it’s fully hardened, typically around 12 hours after the final coat.

Before the membrane goes down, the Soudaprim DP primer does the groundwork. A litre of this deep-penetrating primer consolidates porous and gypsum-based substrates and improves adhesion for the membrane. On absorbent surfaces, skipping the primer is the kind of shortcut that announces itself six months later as a damp patch on the ceiling below. It dries in around 2 hours, so it doesn’t hold up the job.

Where the Soudal Tanking Kit Earns Its Keep

The Soudatape ST is the part most people underestimate until they’ve dealt with a failed wet room. The 10m roll of 12cm-wide elastic sealing tape is pressed into wet membrane at wall-to-floor junctions, internal corners, and around pipe penetrations. These are the places where water finds a way through, and reinforcing them with tape embedded in the membrane is standard practice on any tanking job done properly. The tape stretches with movement and maintains the seal at the joints where a plain membrane coat on its own can be vulnerable.

The whole system is solvent-free, which means no unpleasant fumes while you’re working in a small bathroom with the door closed, and it’s safe for use over gypsum-based boards as well as concrete, screed, and brick. Suitable for both horizontal and vertical application, it covers floors and walls in the same workflow without needing different products for each surface.

For tilers and bathroom fitters, having a matched waterproof tanking kit from one manufacturer also simplifies any warranty or liability questions. Everything in the box is designed to be used together, applied in sequence, and tested as a system. It’s one of those products where the joined-up thinking saves time on site and reduces the chance of a compatibility issue you’d only discover after the tiles are up.