Bedding a shower tray on sand and cement mix

Hi, I have read loads of queries regarding shower trays, however, my question is how much mix to use (firm or wet) and should the edge of the tray be flat on the hardboard and then sealed?

A wet mix, which will be pliable enough to tap the tray down onto, and yet support it's weight is ideal. 3 or 4 parts sand (sharp or soft or a mixture) to 1 part cement, preferably with a bit of washing up liquid or plasticiser in the water when you mix it.

Spread it over the area (priming with a bit of PVA an hour or so before won't do it any harm and will prevent the floor soaking up too much of the moisture which is required to set the mortar), and create valleys and troughs to allow the mortar to spread itself into as you place the tray on and tap it gently with a rubber mallet until it is perfectly level along the rim. You may need to insert some temporary wedges around the edge to support the weight until the mortar does it's trick. Leave overnight before you stand on it.

You may well end up with some (or indeed all) of the bottom of the edge of the tray not being flush on the floor, which the floor covering will mostly cover anyway through it's own thickness (carpet or tiles) or by the layers to be built up to get a perfect finish (plywood for vinyl or tiles)

Thanks for your informative reply, two last questions, what is the approximate minimum depth of cement that should be used and still not quite sure if you put cement right under the very edges as well as the middle?

If it's a stone resin tray it must be evenly supported over the whole base of the tray or you could get stress cracks; the screed is only there to ensure evenly distributed support, 5-8mm will be OK but it depends how uneven the floor is.

lindaleech said:

and should the edge of the tray be flat on the hardboard and then sealed?

Click to expand...

Hardboard? don't bed the tray on hardboard. If you need to lay something down over the floor use a lump of damproof membrane or a bit of WBP plywood but it depends what you intend putting on the floor.

Hi there, many thanks for your reply -no need to worry since it is actually going on a marine ply frame and board, not hardboard, wasn't thinking when I sent my query.

Thanks for this posting -

I had the same question ... put mine in yesterday onto a plywood base.

Primed the ply with a PVA solution the previous day.

Used a tile spreader to get an even thickness of mortar which worked well. the tray is perfectly level.

Becuase my 1200 long tray sat in a U corner I had to use two wooden battens to slide it in on, then pull them out when the tray was in place.

I was so tempted to glue the tray to the ply but glad I didnt!

i sit them on an insulation board to take up any movement