shower waste run

[Robbox]

I'd like to know if the waste run from this shower tray position is going to be too shallow to work satisfactorily

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Hopefully from the drawing it's possible to see the length, it's about 2.2m in total for the shortest most discrete route. The tray will sit on 100mm risers. I've no idea if the run and fall is too shallow. The joists run lengthways so I imagine any waste pipes will have to sit above joist level and cannot be cut into the joists.

 

[muggles]

You're correct that you can't cut the joists (well, you can a bit, but not enough to fully sink a waste pipe into them). Recommended fall on a waste pipe is 44mm per metre, so pretty close to 100mm in your case. Minimum permissible is 18mm per metre, but not recommended for people with long hair!

 

[Robbox]

Thanks for this information. I could always turn the shower tray around, with the other handed version of this tray. That would bring the waste out close to the wall, see JPEG.

But I feel it leaves that awkward little 400mm corner space (bathroom needs a cupboard or shelving) and the door to shower feels less convenient. There is a wide window on the waste gulley wall, 400mm in from right corner.
The floorboards will be coming up and replaced with 22mm ply. So that's 122mm in total. That's just about enough fall, as you say.

 

[Hugh Jaleak]

Use a shallow access shower trap, and fit a cleaning eye on the outside where the pipe turns to head to the gulley, Will give you options for cleaning in the future, without destroying the bathroom.