Gulley trap

[Mr Blobby]

So on the plans I have a gulley trap in the plant room and another in the garage.  What exactly are these and do I need the one in the garage for building regs?

 

We will have a KORE foundation so assuming the gulley trap is a dry trap under a drain in the floor, then is the trap installed (or a former) before the pour; What have others done here?

 

 

[PeterW]

Why ….?? Would never install gulleys internally as they need a water seal to make them work. Stub stack in the plant room with a boss head to take overflows etc.

 

Garage - depends what is going into there ..? But again, sealed is preferable.

[Mr Blobby]

3 hours ago, PeterW said:

Why ….?? Would never install gulleys internally as they need a water seal to make them work. Stub stack in the plant room with a boss head to take overflows etc.

 

Garage - depends what is going into there ..? But again, sealed is preferable.

 

Why indeed?  My paid professionals told me I should install a gulley trap in the plant room, which I took at face value, what with them being the professionals 🙄

 

There's actually already a stack in the plant room to service the en-suite above, so a boss strap to that for the tundish and overflows then?  That makes far more sense for far less effort.

 

As for the garage, is there any BCO requirement for a drain in the floor?  I'd like a cold water tap in the attached garage but there is space for a small sink with trap in waste under the sink that seems far more sensible.

 

Edited November 22, 2022 by Mr Blobby

[Conor]

I'm putting in a basic shower trap in the corner of my plant room, connected to a soil pipe by a 40mm waste pipe. This is to mitigate a burst / leak from the manifold, heating system etc. 

 

I don't think BC will allow you one in the garage due to the risk of oil/chemical contamination. 

[Nickfromwales]

Tell the professionals that the water in the trap will soon evaporate and stench will be coming out into those spaces!!!

[Mr Blobby]

17 minutes ago, Nickfromwales said:

Tell the professionals that the water in the trap will soon evaporate and stench will be coming out into those spaces!!!

 

That's what I was worried about.

 

So what's the solution if the traps dry out?

[Nickfromwales]

22 minutes ago, Mr Blobby said:

 

That's what I was worried about.

 

So what's the solution if the traps dry out?

Get one of those angry dogs that over-salivates, and get it to dribble into it. 

👍

[Nickfromwales]

Or, 

don’t listen to the bell-ends that gave you that advice, and install stub stacks and NOT chuffing gully traps. 
 

 

Will save considerably on dog food also. 

[Radian]

An article I was reading in Architects Journal states the following: "Rules on the use of stub stacks are commonly forgotten. Firstly, the floor served by the stub stack should be no more than 1.3m high from the invert of the drain that it connects to."

Why is this?

[Mr Blobby]

3 hours ago, Nickfromwales said:

Or, 

don’t listen to the bell-ends that gave you that advice, and install stub stacks and NOT chuffing gully traps. 
 

 

Will save considerably on dog food also. 

 

at the risk of sounding stupid here, how does the sub stack prevent the stink coming into the plant room?  It is after all connected to the same waste system and any traps in the plant room will still dry out. 

Edited November 22, 2022 by Mr Blobby

[Nickfromwales]

15 hours ago, Radian said:

An article I was reading in Architects Journal states the following: "Rules on the use of stub stacks are commonly forgotten. Firstly, the floor served by the stub stack should be no more than 1.3m high from the invert of the drain that it connects to."

Why is this?

They mix up definitions there, so their statement is essentially cannon-fodder.

What they refer to is a single rising foul pipe that terminates at an appliance without 110mm ( or any ) need for ( or presence of ) air admittance.

For eg;

You can have a foul connection to a ground floor WC which simply has a pipe rising out of the slab that a bent pan connector is then fitted into. Then the WC pushes back onto that pan connector. Job done. 
The gotcha is, that at, or lesser than the aforementioned 1.3m, you will not get sufficient vacuum in the vertical pipe ( caused by the flushed water / solids forming a pellet and sucking air downwards behind it as it falls to the invert ) to require full and proper air admittance on that particular connection, or indeed cause any detriment whatsoever.

 

If for eg, you repeat this on the 1st floor, when you flush and the pellet heads south, there will be a significant vacuum created behind the falling pellet and any traps, plus the throat of the WC itself, will all be sucked dry. That then leaves stench to enter the room via the foul connection as the trapped water in the traps is no longer there.

So; 

If the external groundwork’s are very deep you could still require an AAV on even a ground floor WC, but NOT if the invert of the outlet of the WC and the invert of the external soil network are at, or less than, 1300mm apart. 
 

Note, the term invert refers to the lowest point where the flushed items turn to horizontal after falling vertically down. ( in a nutshell 🌰). 
 

Stub stacks are normally seen boxed in at around 1200mm off the floor in bathrooms of yesteryear, and typically will have a removable top / panel to gain access for service of, a full 4” ( 110mm ) AAV fitted atop the stub.
 

These are often introduced where there is also a basin, or a shower / bath / sink connected to the same rising foul pipe. These need to be protected from the vacuum, so a knee-jerk AAV on top of the stub stack will be fitted for ‘Justin’, sometimes even if completely unnecessary. 
 

Best to identify where these are necessary so as to avoid ugly boxing-in in bathrooms etc. 
 

 

Justin case. 

[Nickfromwales]

14 hours ago, Mr Blobby said:

 

at the risk of sounding stupid here, how does the sub stack prevent the stink coming into the plant room?  It is after all connected to the same waste system and any traps in the plant room will still dry out. 

It will either be capped or have a 110mm AAV atop. 
The connections to it will end with traps at appliances / outlets eg no pipe work directly open to atmosphere. 
👊

Edited November 23, 2022 by Nickfromwales

[Mr Blobby]

58 minutes ago, Nickfromwales said:

It will either be capped or have a 110mm AAV atop. 
The connections to it will end with traps at appliances / outlets eg no pipe work directly open to atmosphere. 
👊

 

Ok, so I get it about the AAV on top of the sub stack. 

 

But then if there is a boss strap connecting a waste pipe for overflows in the plant room, then the trap in that overflows pipe may dry out and the stink comes back in?  No?  What am I missing?

 

[Nickfromwales]

34 minutes ago, Mr Blobby said:

 

Ok, so I get it about the AAV on top of the sub stack. 

 

But then if there is a boss strap connecting a waste pipe for overflows in the plant room, then the trap in that overflows pipe may dry out and the stink comes back in?  No?  What am I missing?

 

Nope. We use a waterless trap for connecting things which don’t discharge daily / weekly. 
 

https://www.toolstation.com/mcalpine-macvalve-1-self-closing-valve/p26058?store=JT&utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&mkwid=_dm&pcrid=&pkw=&pmt=&gclid=CjwKCAiApvebBhAvEiwAe7mHSFZxKSNNne-U_rdi4E9jpOrsCTjoaEruvU6gpyuCuMDJ7XT1oiycNRoC8kgQAvD_BwE&gclsrc=aw.ds#full-desc
 

Commonly known as a ‘fanny’ trap….. ( your M&E guys should be familiar with that phrase  ). 

[Mr Blobby]

15 minutes ago, Nickfromwales said:

Nope. We use a waterless trap for connecting things which don’t discharge daily / weekly. 
 

https://www.toolstation.com/mcalpine-macvalve-1-self-closing-valve/p26058?store=JT&utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&mkwid=_dm&pcrid=&pkw=&pmt=&gclid=CjwKCAiApvebBhAvEiwAe7mHSFZxKSNNne-U_rdi4E9jpOrsCTjoaEruvU6gpyuCuMDJ7XT1oiycNRoC8kgQAvD_BwE&gclsrc=aw.ds#full-desc
 

Commonly known as a ‘fanny’ trap….. ( your M&E guys should be familiar with that phrase  ). 

 

So dry trap above ground into sub stack ok.  Dry gulley trap in floor (is there sucha thing) not ok ?

[Nickfromwales]

4 hours ago, Mr Blobby said:

 

So dry trap above ground into sub stack ok.  Dry gulley trap in floor (is there sucha thing) not ok ?

For completeness, you will not, I repeat NOT, be putting in the gulley pots that the fannys have recommended. 
 

👊.