How to Install an AKW Tuff Form on a Concrete Floor

Installing an AKW Tuff Form on a concrete (solid) floor is a popular choice for ground-floor wet rooms. Because there are no joists to work around, it's often more straightforward than a timber install — but it does involve cutting into the slab to recess the former and waste. This guide walks through the process.

Important: this is a general overview. Always follow the official AKW installation instructions supplied with your former, comply with Building Regulations, and use a qualified installer for the plumbing and waterproofing.

What you'll need

• AKW Tuff Form former and a compatible gravity or pumped waste
• Tanking (waterproofing) kit
• Tile adhesive or suitable bedding compound
• Self-levelling compound (if required)
• Angle grinder/disc cutter, SDS drill, trowel, spirit level
• Your chosen floor finish — tiles or safety vinyl

Step 1: Plan the position

Decide where the showering area and waste will sit, keeping the waste run as short and direct as possible. On a solid floor you'll usually need a gravity waste with enough fall to the soil stack — if you can't achieve fall within the slab, a pumped waste (PGTF) is the alternative. Dry-position the former and mark its outline and the waste location.

Step 2: Cut and chase the slab

Cut a recess into the concrete so the top of the former sits flush with the surrounding floor level, allowing for your floor finish. Chase a channel for the waste pipe, maintaining the required fall back to the drainage connection. Remove debris and dry-fit again to check levels.

Step 3: Fit the waste

Connect the waste to the former and to your drainage run, following the waste manufacturer's instructions. Test the connection for leaks before going any further — this is far easier to fix now than after tiling.

Step 4: Bed the former

Bed the Tuff Form into tile adhesive or a suitable compound across the full underside, pressing it firmly so it's fully supported with no voids. The ribbed underside helps grip and prevents movement. Check it's level (the pre-formed 1:16 gradient does the work of directing water to the waste — the former itself should sit true). If you need to trim the former to fit the recess, you can cut it to within 150mm of the waste.

Step 5: Tank (waterproof) everything

This is the most critical stage. Apply your tanking kit over the former, the surrounding floor and up the walls to the required height, paying special attention to the joint between former and floor and around the waste. Skipping or rushing this step is the number-one cause of wet room failures.

Step 6: Lay your floor finish

Once the tanking has cured, lay your tiles or weld your safety vinyl, finishing neatly around the waste grate. Make sure the finish maintains the fall to the waste so water drains freely.

Frequently asked questions

Do I need to cut into a concrete floor for a Tuff Form?

Usually yes — the former is recessed into the slab so its top sits flush with the surrounding floor, and a channel is chased for the waste pipe.

Can I use a Tuff Form on concrete if I can't get drainage fall?

Yes. Where a gravity waste can't achieve sufficient fall within the slab, a pumped waste (PGTF) can be specified to pump waste water away.

How is the former fixed to a solid floor?

It's bedded into tile adhesive or a suitable compound across its full underside so it's completely supported, with the ribbed base helping prevent movement.

Why is tanking so important?

Tanking waterproofs the former, floor and walls. Without thorough waterproofing — especially around the waste and the former-to-floor joint — water can penetrate the structure and cause serious damage.

Ready to start?

Browse the AKW Tuff Form range and pick your size and waste. New to formers? Read our AKW Tuff Form buying guide, or our guide to installing on a wooden floor.