Coram Stone Resin Shower Trays: Flat Top or Upstand, Which Waste, and When You Need a Riser Kit

A shower tray is the one thing in a bathroom that gets stood on every day, and it is the one thing that gets replaced when it starts to creak. Acrylic trays flex. Steel trays ring. Stone resin trays, a moulded mix of resin and stone filler with a gel or acrylic surface, do neither, which is why they are what most fitters put in when the customer says they want it to last.

This guide covers the Coram stone resin range: what the shapes are for, flat top against upstand, which waste, and the riser kit question.

Why stone resin

Coram's trays are a stone resin body with a high-gloss acrylic cap, moulded together so the surface cannot delaminate. The process leaves them around 30% lighter than a conventional stone resin tray, which is the difference between one person carrying a 1200 x 900 up the stairs and two. The surface is anti-bacterial and the tray is 50mm high, so it sits low to the floor without needing to be recessed. Ten year guarantee, tested to EN 14527 Class 1.

The four shapes

Square and rectangular

The flat top tray runs from 760 x 760mm square up to 1700 x 900mm rectangular, nine sizes in all. The waste is 147mm in from the corner, or centred on the 1700mm trays. Square sizes go in a corner or alcove with a pivot or bi-fold door; the rectangles take a sliding door or a walk-in screen, and the 1700 sizes are the ones that replace a bath.

Quadrant

A quadrant tray has a curved front on a 550mm radius and goes in a corner under a quadrant enclosure. 800 x 800mm and 900 x 900mm. The 550 radius matches the Coram Optima 6 quadrant and most other makes.

Offset quadrant

An offset quadrant is a quadrant stretched along one side, so you get a longer showering space in a corner without the tray sticking further into the room than a rectangle would. 1000 x 800mm, 1200 x 800mm and 1200 x 900mm, and each one is made left or right handed. Stand in the doorway facing the tray: the hand is the side the long edge runs along. It has to match the enclosure's hand, so check both before ordering.

Upstand

The upstand tray is the same tray with a lip moulded up the wall edges. More on that below.

Flat top or upstand

On a flat top tray the joint between tray and wall is sealed with silicone after tiling. Done properly with a good sealant it lasts years; done in a hurry it is the joint that fails first, because the tray moves a fraction under load and the silicone eventually lets go.

An upstand tray has a 25mm or so lip moulded into the edges that go against the walls. The tiles come down over the lip, so water running down the wall goes onto the tray behind the tile line and the silicone is a second line of defence rather than the only one. It is the tray for a tiled alcove or corner where you want it watertight for good, and it is what we recommend for a rental or anywhere the bathroom will not be checked often.

The upstand range covers the square and rectangular sizes with four upstands (use the ones you need, the others sit against the enclosure), a 1700 x 900mm with three upstands for a bath-replacement alcove, and 800 and 900 quadrants with two.

Upstand trays must be fitted before tiling. A flat top tray can go in after.

The waste

Coram trays take a 90mm top-access waste, which is the larger of the two common sizes and drains a rainfall or power shower without pooling. Top access means the trap comes out from above to clear hair, so the tray never has to come up. It is sold separately in chrome or black, and every tray page on our site has a dropdown to add it, so it arrives with the tray.

If you are reusing an existing 50mm waste, it will not fit. The hole is 90mm.

Riser kits: when the waste cannot go under the floor

A 50mm tray sits on the floor, and the waste and trap hang below it, which means a hole in the floor and room underneath for the trap and the pipe run. On a concrete ground floor, or a timber floor where the joists run the wrong way, that is not always possible.

A riser kit lifts the tray onto adjustable legs so the waste runs above the floor, and clips a panel around the front to hide the gap. The Coram kit is 85mm high, taking the tray to 135mm at the rim, and comes with the legs, clips and panel. There is a kit for each shape: rectangular up to 1200 x 900mm (cut to size), rectangular up to 1700 x 900mm, the 900 quadrant, and the offset quadrants. Again, the tray page has a dropdown for it.

The trade-off is a step of 135mm into the shower. If the user cannot manage a step, the alternative is a level-access wet room with a floor former, which is a bigger job but leaves no step at all. The level-access wet room guide covers that route.

Fitting notes

• The floor must be flat and solid. Bed the tray on a thin layer of mortar or tile adhesive on concrete, or onto a plywood base on timber, and check it with a level in both directions. A tray that rocks will crack the silicone and eventually the tile grout above it.
• Fit the waste to the tray before the tray goes in, and test it with a bucket of water before tiling.
• Match the enclosure to the tray, not the other way round. Coram enclosures are made to the same sizes as the trays, and the side panel on the door page is chosen by tray depth.

Where to start

Browse by shape in Square, Rectangle, Quadrant and Offset Quadrant trays, or see the low level trays together. The enclosures are in the Coram enclosure guide.

Send us the floor construction and the space you have and we will tell you which tray, waste and kit you need.