WetBase Shower Tray Installation Instructions 


The followings are the instructions for installing the Wetrooms Online WetBase (standard) on a wooden floor. These instructions and others for concrete floors and the Linear WetBase can be printed and / or downloaded in PDF format here:


Standard WetBase Installation (Wooden Floor)

Standard WetBase Installation (Concrete Floor)

Wetbase Linear Universal Installation (Wooden Floor)


Wetrooms online WETBASE low profile shower trays are designed to create a flat walk in shower area without raised steps or platforms. This tray is designed to be inset into or on top of WOODEN or CONCRETE floors and then tiled over.

The Coated shower tray is pre machined with the correct falls in all directions to the drain which is partly attached to the tray. It requires additional under support which is achieved by fitting plywood panels between the joists.

Conventional floor boards are approx 20mm thick so laying the tray on top of the joists would bring the top of the tray level with the floor boards.

WE DO NOT recommend tiling straight on to floor boards. We recommend that the entire wooden floor is covered in a 10mm thermal tile backer board prior to tiling and therefore you may need to insert a 10mm packer under the wetbase tray to achieve an even level floor area throughout. The tile backer board is a good insulator and the perfect material on which to tile.

If required the tray can be installed on a raised platform, see stages 1a and 2b at the bottom of this page..

Animated installation videos can be viewed here: WetBase Installation Videos

Frequently asked questions (and answers) regarding the WetBase can be found at: WetBase FAQ's




Click on images for enlarged view.


Clear the working area, establish where you want to fit the tray and place tray on top of the floor boards. Mark around the tray with a pencil and draw the position of the waste hole. The tray can be trimmed with a hand saw up to 50mm off any side if required.


Remove the floor boards from the area where the tray is to be fitted. Ensure you take the floor boards back to the centre line of the nearest joist to ensure maximum support. You may have to replace some of the floor boards around the tray to ensure a snug fit.


Identify the position of the drain and trap. Support under the drain with a ply wood timber platform approx 85mm down from top of joists, to prevent the drain dropping after fitting. Test fit the drain and ensure correct alignment before test fitting the (solvent weld) waste pipe.


Connect 11/2 inch ABS solvent weld waste pipe into the end of the drain using the correct glue. The other end of the pipe should connect into the main house waste drainage system in the normal manner. Ensure the rubber seal is fitted to top of the drain. Now test the drain by pouring water into drain to ensure it is water tight.


The tray requires even support underneath and we suggest screwing 50mm x 25 mm runners 18mm down from the top of each side of each joist, and cross noggin with support timbers where necessary. Cut 18m marine ply panels and insert between joists and fasten down to the runners using wood screws. Cut out a keyhole shape around the drain. You may have to extend this area to the nearest joist to ensure correct support for tray and remaining floor.


Test the fit the shower tray to ensure a tight fit, and alignment of drain. Apply a thin bed of flexible tile adhesive to the area where the tray is to be secured using a notched trowel. Fit the shower tray over the bed of adhesive and firm down ensuring the tray is level in all planes.

The Wetbase should be fixed to the under boarding platform securely using a good quality flexible tile adhesive, bought in powder form. The reason is buildings potentially move, albeit only marginally,  as the ground below them shifts according to the time of year and without that flexibility the tiles above the wetbase potentially will move too leading to cracks in the grout or even the tiles themselves. 

See foot of page for further details regarding adhesive.


Now fit the drain trap assembly using the drain securing tool. We suggest you smear a fine bead of silicone around the underside rim of the trap before finally securing into place. Now over lay the remaining floor area with wetbase thermal tile backer boards.




Apply a bead of silicone sealant to the entire perimeter of the tray and allow to cure. Open up the lastogum or Weber tanking kit box and remove the 1 ltr white bottle of primer. Follow the mixing instructions and apply primer to the walls and floor of the area you wish to tank. Allow to dry as per instructions.


Using a 2 inch paint brush apply a thin bead of lastogum paint on the horizontal and vertical joints of the area you wish to tank.



Starting with the horizontal surfaces first, apply the rubberised jointing tape (BLUE SIDE UP) over the lastogum paint. Press any air bubbles out and smooth out the jointing tape and overlap the tape in the corner to form a seamless joint.



Allow the lastogum to dry fully and then apply the first of 2 coats of the lastogum tanking paint to the walls and floor of the wet area. If there is any lastogum left, apply a final coat. The whole shower area should now be a dark grey colour and the blue tape will also be painted over.

NOTE the wetbase wet deck is water proof BUT the joints to the floor and walls will require TANKING with the Lastogum or Weber tanking kit.
The wetroom wet base and tile backer boards can be easily trimmed to accommodate room conditions e.g. out of square corners etc. If during shipping or installation the corners
or edges have been knocked it will not adversely affect the performance of the product. Simply recoat or fill the damaged edges with fixing adhesive and then overcoat with
lastogum or Weber tanking kit.

Laying the wetbase tray to achieve stepped up wetroom floor

The tray CAN also be used on a raised platform if drainage is a an issue or the room design requires a step.
It can also be set into a concrete screed floor. However we do recommend that you seek professional advise prior to installing within concrete screed floor.




If you cannot set the tray level into the floor and have to raise the base up accommodate above floor drainage or avoidance of beams etc we suggest you construct a 75mm x 50mm support frame on top of the floor boards the overall size of the wetroom area and cover in 18mm ply. Then lay wetbase on top and secure
with flexible cement adhesive.
The support frame should resemble a ladder offering support to the tray in all directions. This can be screwed down to the joists underneath but ensure you have planned the exit point for the waste pipe and trap. Cut your marine ply deck to size and test fit.



Place the tray down on top of the marine ply deck and draw round the drain position.
Cut out a key hole shape in the marine ply and ensure trap is correctly aligned. Secure the ply deck down to the support frame. Then fit the tray and secure with cement based adhesive ensuring the tray is level in all planes.

Please return to stage 6


WetBase Fixing Adhesive - Further details:

Under no circumstances should any of the following fixings be used.

  • Solvent based adhesives—they will damage the composition of the Wetbase
  • Screws—they will damage the Wetbase and its the waterproof properties

Ready mixed adhesive—only adhesive mixed from powder should be used. Ready mixed adhesive contains too much water, and additives that extend its shelf life, that can delay or even prevent adequate drying out and therefore adhesion.  Suitable brands of powder adhesive include Weber (Floor Flex or Weberset SPF), Mapei (ProFlex or Keraflex), Granfix, and Larson Proflex.



Animated installation videos can be viewed here: WetBase Installation Videos

Frequently asked questions (and answers) regarding the WetBase can be found at: WetBase FAQ's