Plumbing

Basin waste first fixed at 32mm, can i increase to 50mm

Anonymous user 28/02/2024 - 3.26 PM

I have a wash basin in a bathroom that has been first fixed with 32mm pvc waste. The waste pipe has been run inside a stud wall which has been plaster boarded both sides and tiled inside the bathroom. The sole plate of the stud wall was cut with a holesaw to fit the 32mm waste and is not large enough to change diameter now this has been first fixed. However i have access to the horizontal run under the bathroom as there is no ceiling currently in the room below the bathroom. The waste pipe is run entirely in 32mm for a distance of about 4 metres before it leaves the internal wall of the property and goes external. From regulations and recommendations i have read, the max distance you can go from basin to soil stack is 1.7m on a horizontal run. You can increase this to 3m if you use 40mm waste. If you want to go further than 3m, then recommendation is to go 50mm. So i would probably want to go 50mm waste as much as possible. Q. Can i use a reducer to connect the 32mm to 50mm waste? Q. Where should i go to 50mm waste? Waste is 32mm through the stud wall, drops vertically goes under the floor boards, then uses a 90 degree elbow to run along floor joists horizontally. Should i go as close to the elbow as possible? Nothing else joins this basin waste, it will run to the soil stack indepently with its own strap on boss. Soil stack will include WC (top of stack), bath (200mm from WC waste), shower (200mm from the bath waste), then this basin waste. Many thanks