Fiiting waste pipe

[tryhard]

Hi All

Help please.
Kitchen units arriving next week, all pipework in place. Undermount sink in granite worktop.
I need to get all the kitchen units fixed, to get the template done for the worktop. As you can see the waste will need to be cut back, the sink and tap will be located immediately above the new copper hot/cold feed, in the middle of a 1000 sink unit. Sink is single 450 bowl.No dishwasher/washing machine.
At present the waste is solvent bond. What do you suggest is the easist way to cut the waste and feed it through the shiny new kitchen units with the minimum of damage and have it ready to connect up to the sink u bend/waste. Are there push/fit plumbing waste bits or does it all need solvent bond. Many thanks, any advice gratefully received.

 

[uug197h]

push fits do not fit with solvent pipe you will need to use a Compression fitting (screw together)that will let you use the pipe thats in now and then push fit up to the sink

 

[mighty-metal]

Do not use any fittings other than solvent bonded foe waste pipes that are not accessable.
Imagine a blockage. cleaning rods are used, they will simply push the push fits off, the water starts to run away from the sink, you feel pleased,a job welldone. you can imagine the rest.....

 

[tryhard]

Thanks for advice just one sorry one further question.

The waste pipe changes diameter from 6mm on the floor to 4.5mm from the elbows up to the sink. You can see this on the photo. When I cut it back to bond new run along floor and up to sink can I use 4.5mm as this will fit behind the units better. Only 1 single sink, no washing machine/dishwasher etc, fairly light use.

 

[mighty-metal]

To do this job properly, you need to start with the size of the waste prob 40mm and the lenth of the pipe run to the stack or drain. For a 40mm pipe maximum run is 3metres, with an incline of 18 to 90mm fall per metre. If the run is greater than 3metres then tou have to go up to 50mm pipe allowing 4metre run. These can be found in buiding regs. If you follow these regs it will ensure a waste which is self-cleaning,low noise and the trap is not lost.