Waste run off from slimline (4mm) shower tray?

[Rebecca]

Hi All,

We will be having a new slimline shower tray installed and have heard that they dont drain very quickly as they are so shallow. We have bought this so pls don't tell me to not buy it!

My query is whether it would make any difference to the drainage speed if the waste pipe has as few pipe joins as possible? The pipe cd go straight out to a drain but it will look rather unslightly on front of house. Otherwise, it could run into a different drain but means about

3 pipe joins at different angles but plumber thinks more joins means it might drain slower (or is he just keener on simpler job?!).

Thanks Vx

[Lobster]

Yes - it's not joins per se, but the corners which the water will have to go round which will certainly slow down the flow.

Not entirely sure what this slimline tray is all about, but the real issue is the gradient on the drainpipe as it runs away from the shower tray.

David

[Calvin]

As far as I can tell the slimline-ness of the shower tray will only effect the rate at which the water drains from the tray to the outlet. The gradient and routing of the waste pipe will effect the flow rate of the water in the pipe. Of course when fitting a slimeline tray you often have less opportunity to get a good gradient on the pipe which is where poorly installed drainage fails. The building regs, which are available online, give acceptable minimum and maximum gradients for the drain pipe and IIRC also include details of how to account for bends. If you stick to the rules it should work well.

We have a very shallow slimeline shower tray and I have to say it works perfectly. It is designed for use with powerful showers though and includes a high flow trap and 50mm outlet pipe - so maybe not your average tray. There was no way I could get the required gradients while keeping the waste pipe above the floor joist so the compromise I made was to go through the ceiling/floor void and run a 1.5m section boxed in at the ceiling height of the room below. The waste run is maybe 2m long with 2 bends.