Guide 3 - Wetroom Kit Installation

DIY Wetroom supplies detailed installation instructions with each kit, however at the planning stage you might want to know a bit more about how each type of kit is installed so you can make a more informed choice.  

 

Note: Guide 2. "Wetroom floors and drainage" explains the basics behind choosing the right kit for your wetroom.

 

This guide explains the basic installation of:

Maxxus (structural) shower deck wet room kit – the easiest and quickest kit to install. 

Maxus Wetroom Kit

 

 

 

Underlay (foam cored, non-structural) shower deck wet room kit – lower cost but involving a little more work on timber floors. Perfect for concrete floors.

Underlay wetroom kit shower floor former

 

You might also want to have a look at the supplementary guides covering:

 

Guide 4. Tips on the drain and waste installation – so you can see how easy it can be.

 

Guide 5. Tanking, Waterproofing, Tiling options and underfloor heating – how to finish things to perfection. 

 

Note: If you are fitting electric under tile heating it is recommended to have insulation just below the element so in the options described look for the techniques that involve a layer of tile backer board across the complete floor.

The rest of job will be to plumb in the shower and then to select and fit a shower screen.

 

Installation of Structural Wetroom Shower Deck – Maxxus Kit.

Maxxus decks are load bearing wetroom shower trays that are rated up to 470kg when installed over joists at 400mm centres.  They are suitable for use with both vinyl or tiled floors.

Because they are rigid they can be inset directly to the floor joists so minimum joinery work is required.  They can also be overlaid on top of an existing floor this technique is similar to the non-structural underlay deck fitting, see below.

A Maxxus kit can also be used on a concrete floor although the advantages of a solid structural deck are negated in this situation unless a vinyl floor covering is used.  The installation would be same for a non-structural deck so please see the section below.

Steps to installing a Maxxus Wetroom Tray on a suspended timber floor

1.You will have chosen a deck of the size you need with a drain positioned  so it will be clear of any joists.  The floor will be level and in good condition.

2. Lay the tray on the floor in the position it needs to be.  By luck or good judgement this should be in such a position that 1 or 2 of the edges are positioned over joists.  (Most guides show this to be spot on but at DIY Wetroom we live in the real world).  If they don’t then it is not too much of a problem.

floor cut out for wetroom deck installation

Cut out in the floor may not match joists or boarding joints

 

Note:  The tray can be cut down as long as you have enough of the wet area covered. This allows walls that are not at 90 degree to be matched. If the tray overlaps a joist it can be cut back so the rest of the flooring has a joist to rest on and to adjust the drain point so joists are cleared, otherwise install a noggin for support. 

3. Draw around the tray then move it out of the way.  Cut through the boards or chipboard and remove that section of the floor.  Small or weak bits of board are best removed and replaced with plywood.

4. At this point you will be able to see the thickness of the existing floor boards or chipboard sheets. It is most likely that these are around 18mm so the 22mm Maxxus deck will stand proud of the rest of the floor by around 4mm.  This gives the height needed to add 4mm plywood, tile backer board (best for with under tile heating) or the DIY Wetroom plastic ply to the rest of the floor to give a good surface to tile on. 

Deck levelled with floor

Match the floor level using Tile backer board or Plywood

 

5. The Maxxus tray will sit happily on the exposed joists and take any load without distorting. However the unsupported edges of the timber flooring are likely to shift and you also need something to screw the edges of the Maxxus on to.  Strips of 18mm plywood can be screwed under any free edges of flooring.  If you think any edges need extra support then add noggins between the joists as well.

wetroom flooring edges reinforcedFlooring edges reinforced to stop movement between floor and deck

 

The Maxxus deck should fit snuggly in the cut-out resting on the joists with timber around the perimeter so it can be screwed down.  

6. Now start fitting the drain. First construct a platform that the drain can rest on during assembly.  This should be directly below the hole in the deck and slightly lower than the drains final position.  This could be a bit of ply spanning between the joists. 

7. Drop the deck in to position and mark the centre of the hole on the platform. Remove the deck.

Massus drain fitting

8. Now you can install the waste pipe and connect it to the wetroom drain using solvent weld and the supplied adaptor if required. (See the Tips on the drain and waste installation for more advice).

 

9. After doing your final checks the deck can be dropped in to place and screwed down level.  If you have cut the deck down re-drill some holes around the perimeter first.  The drain can then be pulled up and secured to the deck.  It is now ready for tanking.

 

See the full range of Maxxus square drain kits - Maxxus kits with linear channel drains are also available

 

Installation of an Underlay (foam cored, non-structural) Wet Room Deck Kit

Two techniques are available:  

Over boarding - Which allows the rest of the floor to be insulated with tile backer board, ideal for under tile heating.

Inset - Gives a level floor (depending on flooring thickness) without any over boarding of the rest of the floor. 

 

Over Boarding - Steps to installing an Underlay former on a suspended timber floor

If raising the floor level by 20 or 22mm (depending on the size of the tray) isn’t a problem then this technique is simple and it give great insulation for a warm floor if you also fit under tile heating.

Underlay former over existing floor

Underlay over existing floor leveled off with TBB or Plywood

floor board cut out for drain box

2. Lay the tray on the floor in the position it needs to be.  Mark through the hole to where the drain needs to.  Cut out an area of the flooring between two joists, giving plenty of room to work whilst fitting the drain  

Note: DIY Wetroom recommend the following technique for the most reliable fitting of a drain under a foam cored, non-structual underlay wetroom deck. This technique gives the drain and grid full support, unlike the advice given by other manufacturers.  

3. Now you can start fitting the drain. First construct a solid platform directly below the hole in the deck and slightly lower than the drains final position.  This should be a piece of 18m plywood, slight larger than the body of the drain. Securely the platform  between the joists.  Use the undelay to find and mark on the plywood the exact position of the drain.

Position of drain under wetroom deck

Make a solid base for the drain and mark where the drain needs to be positioned.

 

4. Install the  waste pipe and connect it to the wetroom drain using solvent weld adhesive and the supplied adaptor if required.  (See the Tips on the drain and waste installation for more advice)

5. Add sides to the platform to make a box around the drain. Use a split side to go around the waste pipe or fit that side before the drain is finally glued to the pipe.  Ensure the hole in the side allows the drain to be lifted to its final position.

6. Place a packer under the drain so its top face is flush with the surrounding and level with the surrounding floor.  Fit the gasket to the drain body. Fill the void around the drain with mortar, concrete or expanding foam to fully support the drain body.  (Full details of this procedure are supplied with each kit.)

Drain held in mortar or concrete

For the most reliable floor the drain is cast in place

 

5. The tray can now be stuck down and levelled on to a bed of flexible tile adhesive.  The drain should be secured to the deck before the adhesive has set and falls / levels checked and adjusted if required.  

6. The rest of the floor can then be overlaid with tile backer board or plywood.  It is now ready for Tanking.

 

Inset - Steps to installing a Underlay (Foam Cored)  Wetroom Tray in to a suspended timber floor

If the level of the floor can only be raise by a few millimeters and you have chosen an underlay deck rather than a Maxxus  the follow technique is the solution.

1. The deck can be trimmed to match walls and to get the drain to the chosen position.  The floor will be level and in good condition.

2. Position the tray and draw around it then move it out of the way.  Cut through the boards or chipboard and remove that section of the floor.  As you will need to create a platform for the tray to sit on it is often much easier to remove a larger section of the floor and reinstate a level  floor with plywood around the perimeter the perimeter of the.  

3. Underlay decks have a Foam core and are non-structural so need support under the complete area. This can be done with 18mm ply fitted between the joists supported by noggins and batons.  Free edges of floor boards or chipboard should also be supported by this platform.  The aim is to fully support the tray and make sure the joint to the existing floor is stable.  

support for underlay floor former

The underlay needs full, solid support at joist level

 

3.  The drain and tray is fitted following the same procedure as described in the “Over Boarding” section.  (Full details of these procedures are supplied with each kit.)

4. The underlay decks are  20mm or 22mm and are bedded down on a layer of flexible tile grout so are likely to will stand proud of the rest of the floor by around  2 - 4mm.  If it is 4mm this gives the height needed to add a layer of 4mm plywood or  tile backer board (good for with under tile heating) to make up the level floor. If it is 2mm then the DIY Wetroom Plastic Ply to the rest of the floor will make up the level and give a good reinforced surface to tile over. 

inset underlay leveled off

Level off the floor with Ply, TBB or Plastic Ply

 

See the full range of Underlay square drain kits - Underlay kits with linear channel drains are also available

 

Steps to installing a Wetroom kit on a solid floor

A wet room tray can be installed on top of an existing floor and the rest of the floor built up to the same height or inlaid. The procedure is similar for structural or non- structural decks.

Overlaying  a wetroom kit on a solid floor

This will raise the floor level by 20 or 22mm (depending on the size of the tray) if this isn’t a problem then this technique is simple and it gives great insulation for a warm floor if you also fit under tile heating.

1.You will have chosen a deck of the size you need with a drain positioned  so you can get the waste pipe run to where you need it .  The floor will be level and in a solid but not necessarily perfect condition (good for old concrete floors).

2. Lay the tray on the floor in the position it needs to be.  Mark through the hole where you need to breakout the screed/ concrete to fit the drain.

Cut and break out the cavity you need to accept the drain with about 20mm clearance.  Then chase out the run needed for the waste pipe and break through the wall to reach the external drain. 

Wetroom deck laid on a concrete floor

When breaking out first ensure that no structural element will be disturbed and that the integrity of any damproof course can be maintained.

 

 3. Now you can start fitting the drain making sure the pipe run will have the necessary fall and a small amount of movement to ensure it can be fitted perfectly to the deck without straining any joints. The 40mm waste pipe connects to the drain using the supplied adaptor and solvent weld adhesive.  (see the Tips on the drain and waste installation for more advice).  

5a. Structural decks (maxxus).  These decks can easily span the cut outs in the floor so can be screwed down and the drain fitted.  The rest of the floor can then be screeded to the right level if it is to have vinyl flooring or the floor can be raised with tile backer board giving insulation if it is to be tiled. 

5b. Non structural decks. These need supporting where the concrete has been broken out.   This means the space around the drain and the pipe needs back filling with either a weak sand and cement mortar or powder tile adhesive.  This has to done in such a way that, when the adhesive or mortar sets, the drain and pipe is in exactly the right position.  To do this the back filling and bonding down of the deck needs to be done at the same time so the drain can be fitted to the deck and the back filling flows around the final position of the drain and pipe.

  

Inset a wetroom kit in to a solid floor

Any deck can be inset in to a solid floor with a similar proceed as for overlaying a solid floor but also chipping away enough of the concrete or screed so the complete deck can be dropped in to ground level.  The deck is bedded in to the recess using powder tile adhesive or a sand and cement mortar.  

wetroom deck set in to a concrete floor

 

See Also :

 

Tips on the drain and waste installation – so you can see how easy it can be.

 

Tanking and waterproofing – with the components supplied in the kit. & Tiling options and underfloor heating – how to finish things to perfection.  

 

All tanking /waterproofing product are available from the DIYwetroom store

 

Other wetroom guides here