Wet Rooms

Hertfordshire, Bedfordshire & Cambridgeshire

Fully Stocked Vans2 Year Labour GuaranteeGas Safe Registered 956889

Wet rooms designed and installed across Hertfordshire, Bedfordshire and Cambridgeshire. Level access, properly tanked, and surveyed against your actual floor construction before anybody quotes. Call 01462 506 374 or request a survey.

Fully stocked vansOur vans carry the common parts, so most jobs are finished on the first visit.

12 month guaranteeEvery job carries a 12 month guarantee on our own labour. No quibble.

462 Google reviewsRated Excellent by the people we have already worked for.

24/7, 365 days a yearGas Safe registered, 956889. A person answers the phone, not a machine.

What a wet room actually is

Not a shower without a tray. A wet room is a room where the floor itself is the shower tray: formed to fall towards a drain, waterproofed as a continuous membrane behind the tiles, and detailed so water cannot get behind or beneath the finish anywhere.

A wet room is a tanking job first and a bathroom job second.

Four things have to be right, and if any one of them is wrong the room fails, usually into the ceiling below.

The fall. Water has to run to the drain from every point.
The tanking. A continuous waterproof layer behind the tiles, not grout.
The drainage. Correctly sized and trapped, and it has to physically fit in the floor.
The structure. On a timber floor this is usually the binding constraint.

Tanking, and the honest position on what is required

The applicable code is BS 5385-4:2015, wall and floor tiling in special conditions. For frequently wetted areas, which expressly includes wet rooms and domestic power showers, it requires that the basic structure behind the tiles should be watertight and should be tanked. It also states that water resistant materials should be used throughout, and that plaster and plasterboard are unsuitable in frequently wetted areas. Tiles should be solidly bedded so voids behind them are eliminated as far as possible, with special attention to sealing the gap between wall and base.

A compliant liquid applied tanking system is tested to BS EN 14891:2017, the product standard for liquid applied water impermeable products used beneath ceramic tiling.

Now the honest part. BS 5385-4 is a code of practice, not a Building Regulation. There is no Approved Document that names tanking a domestic wet room as a legal requirement. The argument for doing it properly is that BS 5385-4 is the recognised standard of workmanship, and that the alternative is a room that leaks into the structure. We are not going to tell you it is illegal not to tank, because that is not true, and companies that say it is are relying on you not checking.

What we will tell you is that grout is not a waterproofing layer. Grout is porous. The waterproofing duty sits entirely with the tanked substrate behind the tiles. A wet room finished onto plasterboard with good grout will look perfect for eighteen months and then show on the ceiling below.

The structural problem, and why some wet rooms cannot be done as drawn

This is where honest surveys separate from optimistic quotes.

A typical timber floor build up runs an 18mm ply lining fitted between the joists finishing flush with the joist tops, then a 22mm floor former above it, then the tanking and the tiles. The drain body and its trap have to sit inside that depth.

The trouble is that joists have strict limits on how much you may cut out of them:

Notches only between 0.1 and 0.2 of the span, and no deeper than 0.15 of the joist depth.
Holes drilled on the centre line only, between 0.25 and 0.4 of the span, no larger than 0.25 of the joist depth and capped at 65mm.
Holes at least three diameters apart, and no hole within 100mm of a notch.

On a common domestic joist those limits frequently make it impossible to get a standard gully and trap into the floor without breaking them. When that happens there are three honest answers: a shallow trap gully, a raised floor with a ramped threshold, or structural alteration with proper trimming. There is a fourth answer, which is to cut the joist anyway and say nothing, and it is the reason some wet room floors bounce.

We survey the floor construction and joist depth before quoting. If a true level access wet room is not achievable without structural work, you will be told at survey rather than on day three.

Falls and drains

There is no British Standard specifying a numeric floor fall for a domestic wet room. The figure we work to is the manufacturer’s: CCL Wetrooms recommends a minimum 12mm fall to guide water to the drain, and that the waterproof membrane extends at least one metre beyond the shower area. We are attributing that to the manufacturer rather than dressing it up as a standard.

Formers do the work here. A preformed sloping panel produces a consistent fall in a way that screeding by eye on a timber floor does not.

On the trap, the Building Regulations are specific: a shower needs a 40mm trap with a 50mm water seal, and every point of discharge must be trapped to prevent foul air. Shallow traps exist for tight floors, and they are a compromise on seal depth rather than a free solution, so where one is used the layout has to avoid the conditions that siphon a seal out.

Linear drains sit against a wall or across the entry and suit a fall in one direction. Point drains need a fall from four directions and a more complex former. Capacity varies by gully and is set by the specific product’s data sheet, so we match the drain to the shower’s actual flow rate rather than fitting whatever came in the box.

Where the floor cannot be drained by gravity, a packaged pumping installation is used, and those are covered by BS EN 12050 and BS EN 12056-4.

Ventilation, which is a regulation

Unlike the tanking, this one genuinely is required. Approved Document F sets a minimum intermittent extract rate for a bathroom of 15 litres per second. In a room with no openable window, the fan must have controls that keep it running for at least 15 minutes after the room is vacated.

A wet room puts considerably more moisture into the air than a shower cubicle with a door, because there is no enclosure containing it. An undersized fan is the reason wet rooms get accused of causing damp, and it is the cheapest part of the job to get right.

Worth noting: a 2026 edition of Approved Document F has been published but does not take effect until March 2027. The 2021 edition applies today, and both give the same 15 litres per second for a bathroom.

Underfloor heating in a wet room

Worth doing, because a tiled floor in a room that is wet by design is cold underfoot and slow to dry otherwise, and drying is what stops the room smelling.

Electric mat under the tiles is the usual answer in a single room, on its own thermostat. Wet underfloor heating makes sense where it is being extended from a wider system.

Two honest cautions. Commissioning a heated screed has a required sequence and waiting period before tiling, which is set by the adhesive and screed manufacturers rather than by a standard we can point you at, and skipping it cracks tiles. And movement joint provision in tiling is governed by BS 5385, which matters more in a heated floor than an unheated one because the floor moves as it cycles.

Where wet rooms actually fail

From the standards and from what we find when we open one up:

Tanking omitted, or not carried far enough up the walls or beyond the shower area.
Plaster or plasterboard left in a frequently wetted area, which BS 5385-4 says is unsuitable.
Insufficient fall, so water stands rather than draining.
Trap seal lost, either because the trap is too shallow or because a neighbouring appliance siphons it.
Joists over notched to get the drain in, which shows up as a floor that flexes and grout that cracks along a line.
Voids behind tiles, so water that does get through has somewhere to sit.

Note that only one of those six is about the tiling anybody can see.

Timescales and cost

Quoted after a survey. The variables are floor construction, whether structural work is needed, drainage position, the size of the tanked area and the tiling. A price given over the phone without knowing the floor is a guess.

On duration we will give you a figure from our own jobs at survey, and we will be clear which days you will be without the room. What we will not do is quote a timescale that assumes no structural surprises in a floor nobody has looked under yet.

Book a survey

Call 01462 506 374 or tell us about the room, including the floor construction if you know it and whether it is upstairs. Across Hertfordshire, Bedfordshire and Cambridgeshire.

Frequently asked questions

Can any room be turned into a wet room?

Not every one, and anybody who tells you otherwise has not looked at the joists. A level access wet room needs the floor to drop for the fall to the drain, and on a timber floor that means notching or altering joists within strict limits. Where those limits cannot be met, a low profile tray is the honest answer instead.

How much fall does the floor need?

Enough to move water to the gully without ponding, formed either in the screed or with a pre formed former. The exact figure depends on the drain and the tile size, and it is set out in the tanking system instructions. What matters is that it is designed in, not chased afterwards.

What is tanking and do I really need it?

Tanking is the waterproof layer behind the tiles. Yes, you need it. Tiles and grout are not waterproof, they are water resistant, and in a wet room the whole floor and the splash zone are getting soaked every day. BS 5385-4 is the code of practice for it, and it is a code of practice rather than a Building Regulation, but ignoring it is how ceilings come down.

Will it leak?

Not if the tanking is continuous, the drain is correctly bonded into it, and the upstands are taken high enough. Almost every wet room leak we are called to is a failure at a junction, so a corner, a threshold or the drain flange, rather than the middle of a floor.

Do I need underfloor heating in a wet room?

You do not need it, but it is the single thing customers say they are gladdest they did. It dries the floor between uses, which keeps the room fresher, and a wet room floor without it is cold underfoot.

How long does a wet room take?

Typically two to three weeks for a full room, including tanking cure times and tiling. Rushing the tanking to save two days is the most expensive saving available in this trade.

Areas we cover

We build wet rooms across Hertfordshire, Bedfordshire and Cambridgeshire.

We work across Hertfordshire, Bedfordshire and Cambridgeshire from our base in Stevenage. If your village is not listed, ring 01462 506374 and we will tell you honestly whether we reach you.

Need help today?

Call and speak to a person, any hour, any day of the year, or get a fixed price quote online.

Get a fixed price quote Call 01462 506 374

Trusted & Accredited Professionals

What our customers say

Speak to a local engineer

Vantage Plumbing and Heating covers Hertfordshire, Bedfordshire and the surrounding areas. Call and talk to an engineer, or send us the details and we will come back to you with a price.

Call 01462 506 374 Request a callback

Gas Safe registered, number 956889. Emergency line answered 24/7.