Bathroom basin waste fittings

[shaw7380]

I have a flat built in the late 60s early 70s and I intend to renew the basin which is an original fitting as I presume the waste is.
My question is regarding the size of the fitting for the waste which is neither 32mm or 38mm but rather something in between. Thing is I need to make an alteration to the waste to line it up with the new basin and new waste kit fitting probably requiring to extend the vertical line and horizontal line, I know I can get extension pieces for 32mm or 40mm but what am I looking for.?

 

[ChrisR]

What material is the pipe? Lead could be an inbetween size, but you can get adaptors for everything in a decent plumbing merchant's

 

[chrishutt]

32mm and 40mm are nominal sizes. Actual outside diameters will be about 35mm and 42mm respectively. But just to further confuse matters, there are two slightly different sizes in each case (e.g. 41mm and 43mm OD in the 40mm nominal size). Typically (but not always) the smaller size is pushfit and the larger size solvent weld.

A 32mm plastic compression connector should fit either size, so this is the thing you need to be sure of adapting your new pipework to the existing stuff. Even if the existing pipe is copper (old 1.25" size) it will fit. I can't see lead waste pipe cropping up in late 60s construction.

 

[shaw7380]

the pipe is plastic