Shower waste installation

[IncompleteCombustion]

I'm currently installing an ensuite, just have a slight problem with the shower waste positioning. The tray can only go in this position and the hole for the 40mm shower waste is positioned through the centre of the joist.

I bought a 90mm mcalpine trap for the tray which has a 45 deg offset but I can't quite manage to get everything to align.

I was going to try two 90 deg bends but read this is not good practice.

Any tips. Thanks

 

[CBW]

What about changing the trap for straight outlet? I take it that the x2 45’s not marry up?

 

[Jackrae]

On the assumption that the drain line follows the line of the joist, can I suggest you make the penetration about 300mm further down the line than it currently is. Then you turn the waste outlet by either 45 or 90 degrees. This extended gap between waste trap outlet and the drain line will permit the use of 45 degree elbows. You might want to fit a metal reinforcing plate over the redundant joist hole to recover its strength.

 

[Hugh Jaleak]

Given the size of the hole you've already made, (it's bigger than I think is really permitted though through a joist), make it slightly larger to accommodate the socket, push the bend back a bit see if that lines up.

I would then look at adding additional strength to that joist.

 

[IncompleteCombustion]

It's a 44mm hole through the centre of a 9" joist, building regs state max hole in a 9" joist is 56mm so It should be ok ?

 

[IncompleteCombustion]

Right thanks for all info guys. Here's my update, would this work ? Is this acceptable, I'm fairly sure there's sufficient fall on the pipe however I know I've used 90 deg bends isn't probably ideal,

What's thoughts?

 

[Madrab]

If there's no other way then don't use elbows, use swept bends

Have to agree about the pipe through the joist too, if it's more than 1/4 size of the joist then it exceeds the max allowed.

 

[IncompleteCombustion]

Thanks. The joist is 225mm and the hole is 44mm so it is not over 1/4 of the joist depth.

 

[Hugh Jaleak]

Right thanks for all info guys. Here's my update, would this work ? Is this acceptable, I'm fairly sure there's sufficient fall on the pipe however I know I've used 90 deg bends isn't probably ideal,

What's thoughts?

That is asking for trouble I'm afraid. You want as few bends as possible ideally, that will slow the flow down, and if (when) it blocks, it will be virtually impossible to clean out.

If you make the hole slightly bigger, (now we know there's definitely scope to do that without compromising the joist strength), to accommodate the shoulder of the fitting, then push the fitting back into the joist, will this allow you to connect directly to the trap outlet? Alternatively a Conversion Bend gives you a bit less height if that helps? FloPlast Solvent Weld Conversion Bend 135° White 40mm 5 Pack | Solvent Weld Waste | Screwfix.com

 

[IncompleteCombustion]

Right thanks for all the advice, this is where I'm up to, pls advise if either of these scenarios will cause any major issues.

1. 3 swept bends
2. 2 swept bends and 2 45's

Thanks