Is this drain plan OK?

[Ben Weston]

Hi all,

 

Wondering if someone far more knowledgeable than me can look over our drain plan to make sure it's workable. We're planning to have one stack in the corner of the upstairs family bathroom which the ensuite in the middle of the house can connect to (we have posi-joists so can pass it through them) and the downstairs kitchen waste can hook into. This will go out to an inspection chamber and then off to the sewer. The downstairs utility room and WC will connect to a separate inspection chamber at the front of the house.

 

Presume I'd need AAVs on the main family bathroom stack and ensuite but unsure how natural ventilation will be achieved - presumably the gulley on the kitchen run won't suffice?

 

Main sewer in our street is quite high so trying to keep runs to a minimum to make sure falls are right.

 

Blue lines: underground drain runs

Red line: upstairs drain run

Green blob: main stack

Purple blobs: inspection chambers

 

Edited October 11, 2022 by Ben Weston

[joth]

Do you want the run from the kitchen to kink at the main stack? It looks like you could make that a straight run with a little movement of the left inspection chamber .

 

Shouldn't the upstairs run from the ensuite connect to the toilet? 

It feels challenging to run that diagonally even through pozi.joists, it maybe simpler to have it go due left and put the main stack in the top left corner of the bathroom, behind the bath 

 

Just misc thoughts, I'm no kinda expert.

 

[Kelvin]

Ours are all straight lines no diagonals 

[Nickfromwales]

How exactly are all the connections to come together at one invert at the “green blob” (lol)?

Assuming the red line connects at 1st floor?

Anyhoo……

You cannot have a change of direction for food wastes or ‘solids’, so main kitchen run would need to be direct to the inspection chamber, and the green stack rising would also connect to the same inspection chamber, each with their own inlet / spur.

The green stack cannot drop into a branch, it MUST drop to a supported REST bend and that must go in a straight line to the chamber.

In an ideal world, you would be taking the underground foul pipe around to the back of the house and you’d be fitting another inspection chamber just for the kitchen. 

Edited October 11, 2022 by Nickfromwales

[Ben Weston]

Thanks for all the comments; this forum is a trove of information!

 

11 hours ago, Nickfromwales said:

You cannot have a change of direction for food wastes or ‘solids’, so main kitchen run would need to be direct to the inspection chamber, and the green stack rising would also connect to the same inspection chamber, each with their own inlet / spur.

The green stack cannot drop into a branch, it MUST drop to a supported REST bend and that must go in a straight line to the chamber.

In an ideal world, you would be taking the underground foul pipe around to the back of the house and you’d be fitting another inspection chamber just for the kitchen. 

 

BC said it was OK for our kitchen waste to connect via a branch into the same run from the stack to the inspection chamber. I didn't know about the stack not being able to connect to a branch though. We've got a rest bend at the base of the stack into a 'Y' branch on the inspection chamber run. That's the "green blob"! We'd prefer a separate inspection chamber for kitchen waste too around the back of the house but the falls don't allow it - we'd be well above ground before we'd got round the back!

 

11 hours ago, Kelvin said:

Ours are all straight lines no diagonals 

 

We have Posi-Joists but I understand the point that, even with them, it'd be difficult to thread through at an angle. Can we go straight left with a slow radius 90 bend to the stack in the corner or is a change of direction not allowed 'above ground' (i.e. in the first floor) either?

 

BC basically said to us "we're happy as long as every run is roddable", which it would be with this set up; but doesn't really help the specifics of achieving that.

[PeterW]

Run the kitchen in a diagonal straight to the bottom left IC - gives you a rodding point and a straight flow. 
 

Also need to fix the dogleg in the utility chamber flow - move the lower right chamber across the front of the house so it’s a 90° intercept.

[Nickfromwales]

10 hours ago, Ben Weston said:

BC said it was OK for our kitchen waste to connect via a branch into the same run from the stack to the inspection chamber. I didn't know about the stack not being able to connect to a branch though. We've got a rest bend at the base of the stack into a 'Y' branch on the inspection chamber run. That's the "green blob"! We'd prefer a separate inspection chamber for kitchen waste too around the back of the house but the falls don't allow it - we'd be well above ground before we'd got round the back!

Ok, that’s all good if your BCO has green-lighted your green blob  

The base of the stack 1000% needs to be a rest bend, and the branch to collect the kitchen needs to be a Y branch set at least 600-800mm downstream between the rest bend and the chamber ( IMO ). As always, your BCO resides above everyone here as they will be signing it off…….but it sounds like your BCO is a pragmatic fellow, happy days! Some are total cocks.

Understood regarding the chamber to the kitchen  

 

So; 

All systems go. “Carry on!”. 👍