Help with waste pipe runs

[adam81]

Hi,

I am wondering if anyone can offer some advice.

I am remodeling a WC room to include a shower, and need to sort out how to arrange the waste.

I have notified BC of the works being done, and will have them come out shortly to inspect 1st fix electrical, and some steel work I have had done. Before they come though I would like to have an idea of what I will do with the waste so I can discuss this with them.

The picture shows how it currently stands..

I have chased a channel for the 40mm shower waste (trying to avoid building the shower up to much) and 32mm basin waste. Initially I was planning on joining these to the exposed 110mm underground pipe. Doing some more reading though has left me with doubts.
As far as I can tell this 110mm pipe goes directly into the property's sewer completely underground. Therefore there is no vent on any of it I assume.

Firstly is it acceptable for it not to have a vent or an AAV somewhere? Not sure how long ago the WC room was installed but it was a retrofit to the house.

If not can I put an AAV inside a dot and dab wall or do these need to be accessible? One option for this if it does need to be is to include it on the bottle trap return to the wall. This would be below the line of the cistern though probably but not sure how to hide it otherwise.

Then how best to connect the various wastes up. The WC is simple enough (I think), get a swan neck/flexible pan connector and drop it into the 110 pipe there. But how should I connect the 40mm shower and 32mm basin. I don't want to have to do as the did before and have it all on show cemented into the end of a 110mm pipe. The 32mm and 40mm cannot run underground correct? Is this even acceptable?

Any advice is greatly appreciated.

More than happy to take more pics if it would help anyone.
Cheers

 

[Hugh Jaleak]

Direct connection for the WC pan to the drain is acceptable provided the distance from the crown of the WC trap to the invert of the drain doesn't exceed 1.3m, think you're well inside that! If there is a vent elsewhere on the property then so much the better.

Fitting a stub stack is one option but it looks very tight for room if you plan to fit the pan immediately where the drain enters the building. You're not leaving much scope to make additional connections below floor level.

 

[adam81]

Direct connection for the WC pan to the drain is acceptable provided the distance from the crown of the WC trap to the invert of the drain doesn't exceed 1.3m, think you're well inside that! If there is a vent elsewhere on the property then so much the better.

Yeah well within that, the bathroom is not much bigger than 2m. There is a vent on top the soil stack that the upstairs WC is connected too. As I said I can only assume this drain somehow connects back to the main sewer there.

Fitting a stub stack is one option but it looks very tight for room if you plan to fit the pan immediately where the drain enters the building. You're not leaving much scope to make additional connections below floor level.

The Pan will sit about 15cm to the left as you look at where the drain enters the building.

A stub stack in the room will be very tight as you say and no where to hide this neatly. If I put the stub stack on the outside, it means exposed pipes in the room. No room to build false walls for pipes and such.

I'll more than happily dig more floor up to make connections below floor level but unsure the best way to connect it all really whilst satisfying all the regs. A Soil Manifold is on option maybe but even this would be very tight and unsightly obviously.

 

[Hugh Jaleak]

The 1.3m is the vertical height from the top of the WC outlet to the bottom of the drain, basically if the drain is any deeper than 1.3m then alternative methods are needed. It doesnt apply here so dont worry.

Best plan may be to run 110mm under the floor to each of the appliance positions, then reduce at finished floor level to appropriate waste pipe.

 

[adam81]

Best plan may be to run 110mm under the floor to each of the appliance positions, then reduce at finished floor level to appropriate waste pipe.

Yes you are probably dead right. That thought had not even crossed my mind.. That's the problem with not being a pro..

So it would then just be a case of having the correct angle on the 110 pipe, and dropping something like this on the upright?

http://www.builderdepot.co.uk/polypipe-single-waste-pipe-adaptor-110mm-32mm.html

Would it need to be solvent welds if in the cement or is push fit still ok?

Can these be cemented just below floor level or should they be beneath the concrete?

Would an AAV be required do you think, or are these simply for when vented soil stacks do no exist? I would think the traps were not draining as when I pulled the basin off the wall water was still in there.

 

[Hugh Jaleak]

Push fit is fine in the concrete, set the waste adaptor at appropriate height, probably at or just below finished floor level with a stub of pipe sticking up to connect to.

AAV's cannot be used as a substitute for a vent, normally another vented stack is required elsewhere on the property. If short waste runs are fitted, unlikely to be any need for an AAV, although anti vac traps or HepVo valves could be fitted to make certain.

My concern would be though, access to this section of drain should need arise. Really need to find out where it goes, especially as a WC is discharging into it. If there is no chamber on that run then BCO may ask one is fitted, or some other form of access is incorporated. If it did block, you need to be able to access it to clear the run.

 

[adam81]

Hugh,

You were right BCO were fine with the runs in 110mm but have asked for an inspection cover that would be sealed.

I've found these http://www.ebay.co.uk/itm/Clark-Dra...mbing_MJ&var=460075318580&hash=item25711f68d6 but they are way overkill for the room.

Does anyone know of anything discrete looking for a bathroom floor that will be tiled? Been googling all sorts for the last 20 minutes and most of what I can find is industrial/external sized stuff.

Cheers

 

[Hugh Jaleak]

The cover in the link is the type of thing you need, choose size appropriate to the chamber underneath. It is recessed to allow the cover to be filled, with carefully cut tiles inside and out to match the grout lines then the join should be fairly unobtrusive. They are just flaming heavy to lift out again should the need arise!

It's never going to be invisible but unfortunately internal chambers are somewhat of a necessary evil.

 

[adam81]

Cheers Hugh.

He also mentioned a rodding eye would be allowed but they are pretty ugly too if not smaller..

 

[adam81]

Ahha. found these. These are what I need I think?
http://www.travisperkins.co.uk/p/os...or-for-3240mm-waste-pipe-110mm/870066/3893452

 

[Hugh Jaleak]

That sort of thing but I wouldnt be paying TP prices.....

Benefit of an internal cover is you can fill it in to match the floor covering, whilst the shape of the rim is visible they dont look too obtrusive. Rodding eyes are difficult to disguise, so would probably be more of an eyesore in my view.

 

[adam81]

Still searching for cheaper places..

TP don't list prices online, can find them for around £5-10

 

[Hugh Jaleak]

£5-£10 is about right, you'd probably pay double that at TP unless you're an account holder.

 

[adam81]

Ok..
All my connections and bits arrived today so thought it would just be a case of joining it all up.

Shower should be fine as I have a riser kit for this if the need arises. However to get the basin waste to be hidden is a little more problematic.

I had intended to stick 90 degree bend on the end of the 110mm pipe and drop the adapter I found on then end having this just below the surface.

But with the falls required on the line and the height the drain comes in at would mean this is a bout 4-6 inches above the planned floor level.

Its not acceptable I realise to the have a compression fit (32mm adapter I linked to) under the floor, but is it acceptable to do the whole 32mm waste in solvent pipe and cement it into the end of the 110mm as per the picture in the first post, or is this frowned on now as well.

It's only basin waste so not under any pressure and should not be getting any foodstuffs or other solids down it.
Cheers

 

[Hugh Jaleak]

How long will the run in 32mm be? I'd still think you'd need to use the correct adaptor into the 110mm, but may get away with running a smaller diameter waste from the end of the 110mm to basin position. Should be fine underfloor in solvent weld, but size required depends on length of run.

Basin wastes can and still do block, hair and soap are usual culprits so I would still make sure access is incorporated into the runs so a 'snake' or similar can be used if need arises.