Lowering bath waste pipe through cavity wall into downpipe

[broontroot]

Hi, hopefully some of you guys can help !

I'm going to be fitting a new shower cubicle and bath, only problem is i've got a concrete floor!
My old shower tray was fitted on top of an 7 inch timber frame, so as the waste shower water would run downhill into the bath waste, before exiting through the cavity wall.

Ideally i'd like to lower my new shower tray, so its not so much of a step out onto the bathroom floor.

My waste pipe, where it goes through the cavity, is 5 inches to the centre of pipe from the floor, i'd like to lower it to floor level but dont know how big a job this would be, and what exactly would be needed to do the job,this would enable me to then lower the shower tray so advice much appreciated.
The cast iron outside downpipe section is 86mm O.D (slightly less than three and a half inches). The plastic bath/shower waste pipe is 40mm O.D

 

[ChrisR]

The only hard bit is altering the cast iron pipe outside.
Either dig down and have a look, then wiggle the CI out of its fitting with the underground(clay) and replace it with plastic, or, look up and cut-in "Timesaver" or "Fernco" couplings. Fernco are easy but look a bit tacky - rubber/Jubilee clip things.

 

[broontroot]

Thanks for the reply.

I was actually hoping that there would maybe be a plastic T-section available to sort of piece in, after removing the cast T-section .

So that cast iron T-section cant be removed without first removing the straight section that goes into the ground?

Another way i thought about would be to make a separate waste hole at inside floor level, right through the cavity wall so it exits around 6 inches away from the cast downpipe, then using a 90 degree elbow fit a short section of straight 40mm waste-pipe, which would go through a hole in the side of the cast downpipe? Maybe chain boring a circle in the downpipe, inserting 40mm plastic waste,and siliconing around it.

 

[stardanny]

Where's the cast pipe going up? Is there any pipes going in above?

Dan.

 

[broontroot]

Where's the cast pipe going up? Is there any pipes going in above?

Dan.

Hi Dan

there is a smaller diameter cast pipe for the handbasin. It goes into the cast iron down-pipe around 1 foot above where the bath waste exits the wall and goes into the down-pipe. (just above the top collar thingy in the pic).
Apart from that the cast iron down-pipe goes right up into the guttering.

 

[broontroot]

Rather than use a 'Timesaver' bolt-on coupling, would it be possible to cut the 40mm hole in the cast downpipe,and insert the 40mm plastic waste, sealing it with silicone?

The plastic shower waste pipe would exit the exterior wall around 8 inches along from the original waste pipe, and at a slightly lower level, therefore i'd only be piecing in a very short section of pvc pipe, by using a glue on pvc elbow.

 

[broontroot]

Thanks.

 

[broontroot]

Rather than use a 'Timesaver' bolt-on coupling, would it be possible to cut the 40mm hole in the cast downpipe,and insert the 40mm plastic waste, sealing it with silicone?

The plastic shower waste pipe would exit the exterior wall around 8 inches along from the original waste pipe, and at a slightly lower level, therefore i'd only be piecing in a very short section of pvc pipe, by using a glue on pvc elbow.

In the end i done it without a 'Timesaver bolt-on coupling', as the pipe length which i fitted into the cast-iron downpipe was very short.
I hired a coredrill, £50 it cost to drill one hole right through the cavity wall, but this enabled me to drop the waste-pipe nearly 5 inches,therefore allowing me to drop my shower tray the same, so it's dead easy to step in and out of now.
You can see where the old waste was compared to the new one.

To cut a hole in the cast-downpipe i used a bi-metal hole-saw, bought from here http://www.toolstation.com/shop/Pow...esaws/Bi+Metal+Holesaw+44mm/d80/sd1530/p91182 for a few quid, it went through the cast pipe in only a few minutes, no problem at all, much easier than i thought!