110mm Drainage through slab - how to get closer to wall?

[Undaunt]

So we’ve a straight run for the new kitchen, from an inspection chamber to a settlement rest bend (it gave us extra depth, to accomodate going under the foundation & to the depth of the inspection chamber invert)

However the closest we could get the rest bend to the wall, leaves it 230mm away from the wall if I come up vertically through the 300mm foamed glass aggregate insulation and 100mm slab.

I would use one of the 110mm-50mm reducer, or 110m-double 40mm reducer to be just above flush with the finish floor level.

This would then require a 87.5* bend back towards the wall in 40/50mm pipe then another 87.5* bend to bring the waste up vertically behind the kitchen units. This seems like it could be prone to clogging.

I had the thought that maybe instead, I could use two 30* bends with a short section of underground pipe between, to bring the 110mm pipe close to the wall where it exits prior to putting the reducer on.

I’m concerned about how stable it will be whilst we are laying the foamed glass aggregate and compacting it then laying the screed around it. Plus it is not the norm, and possibly not to building regs? I think it is unlikely to block however.

What do more experienced drainage folks think?


The plaster line you can see is the finished floor level (50mm cast hempcrete behind!)

 

[CountryFan]

You could use the 2 30 degree elbows. Or instead of using 87.5 elbows, maybe use 45 degree elbows?

 

[Hugh Jaleak]

Go with the two 30° bends as per your photo, it's a sink waste, provided you're not chucking copious quantities of Fat down the plughole, the chances of it blocking are slim, and in the vertical section, even more so. I'd have no issue putting a WC pan on that run.

 

[robinbanks]

Why not just tilt your swept bend over so it's near the wall and use a suitably angled elbow to bring it back near vertical? (You won't need it bob on level if all you're doing is connecting a waste adaptor to it anyway

 

[lostinthelight]

I would consider solvent weld joints if compressing foamed glass around the pipe in the subfloor as it compresses 30%