Drain-Waste-Vent for bungalow

[Kris77]

Hi Folks,

I 'm new here but I greatly benefit from the wealth of knowledge on these forum.

Currently I am working on the final D-W-V layout in my bungalow, please take a look on the drawing.

At the moment we have laid the pipelines, bottle gully for the kitchen sink and 3 way AJ which is taking from all fixtures to the septic tank.
But we do not have a soil stack or vent for the two WC.

I am trying to figure out the best possible solution for my case without obstructing the Patio door with the soil stack outside.

I come up with this proposal:

Adding the 110mm soil stack internally in the Cloakroom WC and run through the loft and roof.

Now, I'm not sure if this would be the best possible solution in terms of functioning the whole system. There will be 2 WC so issues with negative pressure etc.

I will be greatly appreciate if anyone could advice on the following question marks:
1. The proper placement of the soil stack?
2. Would be better to fit AAV in the loft or both together ?
3. Any better options?
4. Should I need add another bottle gully before the 3 way AJ?

Huge thanks in advance,
Kris

 

[Madrab]

With there being so much on the primary run from the en-suite through the studio toilet/kitchen to the main outflow to the ST then I would strongly recommend that the head of the run is punched up out through the roof and open vented, do not put an AAV on it. You will have to cater for positive as well as negative pressure in that set up. Be very careful the way the shower in the en suite is run into that side of the soil run too.

How long are the respective legs? @ 25mm per M fall then that's really at the lower end of what's ideal, I would want a little more than that to ensure self cleaning and minimise any servicing, especially on the toilet side of the soil run. I'd up that to at least 35mm if it can be catered for.

 

[Kris77]

Cheers Rob for your opinion and advice!
The leg from the Main kitchen sink is 11 meters. The run from the Cloakroom WC to the AJ is 9 meters.
If I may ask you yet a few questions I would be much grateful.

So, where exactly you would recommend to fit the soil vented stack ? In the cloakroom behind WC or where is the shower in the en-suite or maybe I should have 2 soil stack vents (one in the Studio bathroom and second in the cloak room )?

 

[Madrab]

The gulley run should be ok if all that is servicing is the sink and associated DW. Again though, optimise fall to minimise any issues, the design standards run from 18mm to 90mm per m - the ideal would be somewhere in the middle ground.

As far as what I would call the main run with the majority of services feeding into it then where you propose to have the vertical dry stack would be fine as that could be designated as the head of the drain, with all of the services connected downstream of it. If that is up and out through the roof with an open vent then that will allow the main run to breathe properly, that should avoid self syphoning or positive pressure. That run really needs to be given as close to optimum fall as possible, that will minimise the chances of restrictions forming and help it to be self maintaining.

Plan the outlet connections properly with the en suit shower increasing to 50mm before the basin connection and to connect to the main soil pipe after the first toilet. Maintain a good fall in that section of waste run to ensure the shower and basin don't have issues and drain well and use an antivac trap on the 1st basin to vent that small section of pipe to avoid the shower seal ever getting pulled.

 

[Kris77]

Thank you so much Rob, I wish I have a knowledge like you.

Just the last and quick question, you mean the antivac trap in the studio bathroom basin ? In the Studio kitchen sink and DW should I fit P-trap ?

 

[Kris77]

it should be something like this ?

 

[Madrab]

Apologies, I read there was a basin in the en suite shower space, as basin was written twice on the original drawing, didn't check the actual drawing. If there's just a shower there then 40mm to the soil pipe would suffice. Try to connect both of the the shower waste runs high enough up the soil pipe to ensure the pipe isn't ever submerged with outflow from the toilet as that could cause negative or positive pressure in the shower waste if there ever was a restriction, though given the open vent stack the risk of that should be kept to a minimum. It may be difficult given the showers would probably be the lowest points on the run.

Antivac on the cloakroom ensuite basin, it would have been in the shower room had the basin I thought was to be there, was there, just to vent that little section of the 'extended' run, one on the studio basin wouldn't go amiss either, if nothing else it'll stop any gurgling of the basin trap seal (self syphoning).

 

[Hugh Jaleak]

Unsure if the Regs in Ireland differ to the UK, but my concern would be with your proposal, is dropping the first WC in on a blind connection, particularly given it's in the middle of the property, along with the bends in the run. Unsure if it would be allowed in the UK< both WC's would need separate, straight runs to exit the footprint of the Building, then common them in a chamber, to give cleaning access to both legs.

Trying to jet a blockage in that run as shown could easily result in an explosion of waste from the first pan and/or any connections on the run.

 

[Madrab]

Maybe it just up here in Scotland but see that type of setup in bungalows up here, bathroom in the middle of the house with a dry stack run up vertically to exit through the roof with a toilet connected further down on the horizontal run and all the services connected to that single horizontal run out to the chamber in the garden, that being said they usually do have rodding access at both ends so it's not necessarily a blind run

 

[Kris77]

Thank you Madrab and Hugh for you opinion and apologize for the late response (no time to scratch the a.. these days )

Unfortunately the setup is not perfect and the pipeline is already laid under building and in the ground so I left with no options and need to find the most suitable solution to the current situation and give a try if its work.

I just made a drawing with section of my house. As you see I placed secondary dry pipe. I wonder if this arrangement is making sense ?
I have few questions regarding to this:
-what angle the connecting pipe should be ?
- can be smaller diameter for example 70mm or better 110 ?
- perhaps one vertical 110 pipe will suffice?

As always much appreciate your opinion.