On 02/06/2019 22:44, Steve Walker wrote:
When I put in our shower, there was a joist partly in the way. I used a
shallow waste, with an elbow mounted straight onto it, dropping down the
side of the joist and notched the joist (and the floorboard above from
underneath to clear the elbow). The notch in the joist was only a few mm
more than already used elsewhere by 3/4" pipes installed from new and
the joist was no longer having to support a full bath, so a little loss
of strength did not concern me.

Unfortunately this waste would be bang right in the middle of the joist
so would need to take approx half the depth of the joist away.

I am now thinking about a narrow shelf (maybe 3 inches) at the opposite
end to the waste pipe end so I could slide the tray down towards the
waste by the required amount. I just wonder if I could seal the `shelf`
properly to make it watertight.