My house design's layout is apparently somewhat challenging for the waste side of things. Attached below is the 'current design' but the runs are somewhat long. Is this "okay enough"? I realise that some designs are near the edge of physics, but we can't all have 5% angle - the main question is how often this will start to cause problems "per year". Having a plumber over once every 5 years isn't the end of the world, but once every week obviously is....

 

 

One note is that I'm not happy with the far right downpipe, I'd want it in the corner of the room, or if needed, at least further up the wall.

Edited December 18, 20214 yr by puntloos

ground floor isn't an issue bring up sewer where its needed, first floor you need to lose them in the stud (unless you want council house style boxing in)which means that stud wall will be wider than normal to accommodate 110mm pipe. Lose the pipe in the elevator shaft and run to it through pozi joists.

You'll need to re-think your ensuite to move that 110mm pipe from where it enters the study, unless you have the floor depth to run it horizontally until it hits the corner.

No services except for the lift/lighting are allowed in an elevator shaft… my understanding of the regs and talking to engineers that maintain mine at work.

All I would add is change up your 40mm runs to 50mm. 

10 hours ago, Dave Jones said:

ground floor isn't an issue bring up sewer where its needed, first floor you need to lose them in the stud (unless you want council house style boxing in)which means that stud wall will be wider than normal to accommodate 110mm pipe.

 

Got it. We'll take a quick look if we can accommodate.

 

10 hours ago, Dave Jones said:

Lose the pipe in the elevator shaft and run to it through pozi joists.

 

9 hours ago, TonyT said:

No services except for the lift/lighting are allowed in an elevator shaft… my understanding of the regs and talking to engineers that maintain mine at work.

 

You might be misreading the floorplan, no pipes in any elevator shafts (there actually is no elevator, just a provisional spot as marked)

 

6 hours ago, Russell griffiths said:

All I would add is change up your 40mm runs to 50mm. 

 

Why?

 

Obviously (?) bigger runs are better for flow etc but do you figure 40 is problematic?

40mm up to 3metres any further up to 50mm

3 minutes ago, TonyT said:

40mm up to 3metres any further up to 50mm

 

Got it. I assume you mean horizontal runs, not drops into svps. Will take a look.

16 hours ago, puntloos said:

 

Why?

 

Obviously (?) bigger runs are better for flow etc but do you figure 40 is problematic?

Bigger is always better. 
 

1 hour ago, Russell griffiths said:

Bigger is always better. 
 

So what happens with small ones that big ones don't have? Clogging, I assume? Or draining very slowly?

 

21 hours ago, puntloos said:

So what happens with small ones that big ones don't have? Clogging, I assume? Or draining very slowly?

 

BRegs give stated max lengths for ‘small bore’ waste runs, iirc max length 3m before upsizing to next pipe diameter etc.

For showers I never run anything less than 50mm, as the air break in that size pipe allows free flow from the bubbles / foam creating an air lock, which happens in 40mm. The difference is quite significant tbh, where the water etc travels in the lower half of the pipe and air is free to travel over the top keeping things flowing very well.

Its an odd phenomenon but it makes a big difference in my experience.

Smaller pipes do slowly clog up from the soap etc coating the inside of the pipe, layer by layer, over many years of use. 32mm waste pipes from basins and 40mm waste pipes from kitchen sinks are the ones that suffer most, with pipes eventually blocking completely. What is found in the cut out sections of pipe are evidence of this. Quite unbelievable how bad they get.

If you are burying / boxing any of this then upside by 1 in every instance. 40mm replaces 32mm - 50mm replaces 40mm etc. For wash basins I run 40mm up vertically and fit a 40mm bend with a 40x32mm reducer in it to come horizontally into 32mm pipe and then to the trap of the basin. Makes a huge difference in discharging water away from the basin.