Drain layout - advice & views please

[hammerswinger]

Hi,
I would appreciate any advice or recommendations on the new layout of my drains.
The drains are being altered because of our new extension on the back of the house, the original inspection chambers are being removed so we don't have them under the extension floor, because of this the run of the 1st floor WC is also altered.

I've looked through the forum and read about sub stacks for ground floor WC's but its a bit confusing when it comes to venting the sub stack, some say it needs to be, others say not, it would be better for me if I didn't have to vent the run from the new WC.

Anyway take a look at my sketch below and see what you think.


Cheers.

 

[DeltaT2]

Regardless of what we say mate, you need to contact your LABC & comply with their requirements. They all have their views on drainage layouts. Most are very helpfull.
HTH

 

[Hugh Jaleak]

Provided the crown of the W.C. trap is no more than 1.3m above the invert of the drain it should be ok to connect directly to the drain. System will be vented via existing stack serving 1st floor bathroom.

I would consider installing a new 450mm I/C at the position shown, using the 2x left hand connections for new downstairs W.C. and gulley for basin/washing machine, a R/H for the connection to existing stack, and then take the straight connection right under the proposed build, with a 225mm chamber immediately outside at the rear, then a run along to the kitchen sink position and provide a gulley externally. This eliminates the run under the floor from the kitchen sink, which could prove difficult to clean out should need arise.

However, as DeltaT2 has said, B.C.O. has the overriding say on what they want to see done. Always best to consult with them prior to carrying out any work, and get it right first time, as B.C.O. will be signing the work off!

 

[hammerswinger]

Hi,
Yeah I appreciated that the BCO has the final word but I'm just starting on the drains so was just wondering if the layout I have planned was anywhere near how it should be.

@ Hugh Jaleak,
The proposed run of pipe from the kitchen sink is the problem, I knew it wasn't ideal.
If I run it as shown in the sketch it will have to connect to the soil stack low down, in fact I don't think I can do it as the connection would more than likely be lower the 450mm last connection level.

The gully for the kitchen sink is a good idea but unfortunately as the shell of the extension is already up I haven't got a lintel in the correct place to bring the 110mm pipe through to get it outside for the sink gully.

Is there a way to connect the waste pipe from the kitchen sink to the 4m pipe from the WC?
Failing that, could I run a 110mm pipe from the new IC to below the kitchen sink then a rest bend with a reducer to take the 40mm waste pipe from the sink. If there was ever a blockage it could be roded from the IC, would that be ok?

Thanks.

 

[Hugh Jaleak]

Could bring up a stub stack in the corner of the ground floor W.C. and connect sink waste, or as you suggest connect the sink directly to the drain. As long as all pipework is accessible for clearance should the need ever arise then it shouldn't be a problem.

I'd check with B.C.O. beforehand though as you dont want to put pipework in only to have to move it because B.C.O. isn't happy with the arrangement!

 

[hammerswinger]

Hi,
Yeah I'm going to find out what the BCO will be happy with before I cut & position the pipe runs, I don't want to find it all needs changing once its in as the pipe adds up to a few quid.
The BCO is a decent bloke & very helpful so I think he'll be more than happy to give it the once over before I start.

I posted my query as I've never really had anything to do with laying fresh drain runs so I was just wondering if I was on the right track.

Thinking about my suggestion of connecting the kitchen sink to the 4m WC pipe, I think this is out of the question as this would have to be done with a strap on boss which AFAIK are not meant for underground use.

I think my best option may be to run a 110mm drain from the new IC to the kitchen sink, doing it this way also virtually guarantees no problems with poor flow or blockages.

Cheers.

 

[hammerswinger]

Hi,
I've been thinking of a way to vent the soil system using the existing vent part of the original soil stack, if I could use this it would save me having to have a vent pipe coming through the roof of the extension and going up the side wall of the house.

The original soil stack is to the Right of the 1st floor WC, could I use a 90 degree branch to connect the WC and the vent pipe?

The pipe that drops from the 1st floor to the ground floor would not be vented.

Take a look at my amended diagram to see if it make sense.

Thanks.

 

[hammerswinger]

Can anyone advise if this would be ok? I would like to know if it's a possibility before I talk to the BCO.

Thanks.

 

[DeltaT2]

Most LABC officers will ask for a SVP at the nead of the drain, say beside you GF WC?

 

[hammerswinger]

Lets just say the BCO didn't ask for a SVP though, would my proposed system work ok?

I'm just not sure if you can have the soil stack dropping from the 1st floor to the ground with out a vent on top of it, even though the vent would be at the head of the run going into the stack.

Cheers.

 

[DeltaT2]

Oh it'll work, but Building Control will want it done their way regardless.

 

[hammerswinger]

Thanks for that.
At least if I know the system I have on the 2nd diagram will work I have room to negotiate with the BCO, actually he a nice bloke who's very accommodating.

All I'm trying to do is to save having to have the vent of the soil pipe coming through the roof of the new extension and up the side wall of the house. The houses on the estate all have internal soil stacks so I'm trying to keep it looking the same as before the extension.

Thanks.

 

[DeltaT2]

No problem mate & I hope you get sorted.

 

[hammerswinger]

Thank for your help, I'm off to speak to BC this afternoon so I'll post back and let you know the outcome.

Cheers.

 

[hammerswinger]

Hi,
Well I went to discuss my proposed drain layout with BC this afternoon and good news, the guy said everything I wanted to do was fine.
He understood my reasons for not wanting to have to run a vent pipe up the side wall of the house and agreed that using the top portion of the existing internal soil pipe was a good idea, I just hope it's as easy as it sounds

He also said that I don't need to vent the branch to the GF WC as the floor level of it is less than 1.3m to the invert of the drain.

So happy days, I can get on with the drains now.

Thanks to everyone for all of the advice, I'm sure I'll be back asking more questions soon.

Cheers.