Critique My Drainage Plan

[Jenki]

Could you please cast your informed eyes over my drainage plan,  and tell me if I've missed anything. 

I've used a NHBC tech sheet for some guidance, namely if I use a rodding point (bottom of the diagram) I can then branch off the main run for Bath and Shower.

The two WC's and SVP will be connected with a Y branch and 45deg coupler to give a larger radius.

 

SVP will be in the plant room and vented through the roof, I plan to use this for the waste for Utility basin, WC basin, and drain / blow off for UVC (150L UVC)

 

 

Lastly I plan to have a walk in tray and want to use this  or similar trap which will be connected to the 110mm pipe. (The House slab in the shower area will be left lower, so I can form a tray with screed later.

  

[ProDave]

Personally I would take the bath out through it's own pipe at the front (bottom of picture) with a drain run along the front to merge with the one from the back.

[saveasteading]

Agree with ProDave. For the sake of 5m extra drain run i would have the external run on both sides of the house, and keep all internal pipes simple and short.

A chamber outside the bathroom could take 2 connections. All very easy to rod, but less likely to block in the first place.

[Jenki]

3 hours ago, ProDave said:

Personally I would take the bath out through it's own pipe at the front (bottom of picture) with a drain run along the front to merge with the one from the back.

 

40 minutes ago, saveasteading said:

Agree with ProDave. For the sake of 5m extra drain run i would have the external run on both sides of the house, and keep all internal pipes simple and short.

A chamber outside the bathroom could take 2 connections. All very easy to rod, but less likely to block in the first place.

My thoughts being that the bath and shower would flush this pipe and reduce the chances of blockages .

And it's an extra 15M of pipe and two ic's.  It's not going to break the bank but this is the level of saving I need to think about 😬. But at the same point I'm not trying to cut corners.

[MJNewton]

Yeah I'd second/third the dual-run approach. Another benefit is the independence/redundancy it provides if there's a catastrophic problem somewhere along the way as it gives you a backup to keep you going whilst a solution is found - it turns what might otherwise be an emergency into more of just a problem. Such breathing space can often allow cheaper solutions to be employed if you want to help justify things financially.

Edited January 10, 2023 by MJNewton

[saveasteading]

3 hours ago, Jenki said:

And it's an extra 15M of pipe 

Not that much, as the internals are reducing. But I agree in principle and am more used to reducing than increasing runs.

But the dual run gives you very simple runs and connections. If there is any issue, it is a simple rod to chamber. The internal one has multiple junctions and connections, and angles that could be fiddly. 

Once the 'water' has dropped over the edge in the chamber, it isn't coming back.

The chance of 2 x wc plus a bath draining and clashing at the same time is low, but worth minimising.