shower waste pipe

[minnie1]

is there a recommended angle of fall for shower tray waste pipe?.we have had a shower fitted and I am concerned that the run is quite long and the fall may not be sufficient,where can i find details please.Thanks.

 

[dextrous]

18mm to 80mm per metre. However, there are restrictions to lengths without additional venting provisions - so what length are we looking at?

 

[minnie1]

Thank you dextrous, very kind of you to help.

Total length of 32mm waste from shower to soil pipe is 3.55 metres, including 1 x 135deg. angle and 1x 90 deg. angle before connection to soil pipe.

 

[Bahco]

Change it to 40 mm waste and you are just in the ballpark.

 

[dextrous]

Yep - 40mm is a must! (or even 50mm if you want)

 

[Nige F]

And use 92and a half degree swept bends . Those 90knuckle bends are

 

[minnie1]

Thanks very much for your help, all of you. We shall be having some interesting conversations with the shower installers.......

 

[dextrous]

Are you sure they used 32mm?

 

[minnie1]

Just got the guy round as the shower drains too slowly, The pipe is 40mm,
He has put 2 x 45 deg joints where the new drain joins the existing drain from the old bath, but the water is still not draining from the shower quickly enough.
May be there just isn't enough fall? The loo is being taken out now, and he is testing for blockages. Yuk!

 

[dextrous]

Just got the guy round as the shower drains too slowly, The pipe is 40mm,
He has put 2 x 45 deg joints where the new drain joins the existing drain from the old bath, but the water is still not draining from the shower quickly enough.

Could be a problem with the shower trap. We've had a couple of problems on here which relate to the design of some new shower traps which are causing slow drainage, even though the wastepipes are fine.

 

[minnie1]

Thanks, dextrous. The outcome is that a new showertrap has been inserted, and 45deg joints added where there were 90deg joints. The piping throughout is 40mm, and the fitter put a bit more slope on the pipes under the sink and toilet.

Seems to be just fine now.