Down or out?

[dpmiller]

OK so we've got three sets of outlets at the back of the house- 1. kitchen sink and DW, 2. the utility sink and WM and the drains from the downstairs shower and basin, and 3. the downstairs WC as well as all the upstairs bathroom. There's 650mm from the top of the footings to the top of the subfloor, and another 225mm or so to FFL.

 

What looks handiest-

1. 40mm out through the wall, drop into gullytrap.

2. 50mm horizontally through the floor insulation and out through wall to rear entry gully

3. 110m out through wall to a vertical soil coming out of a rest bend

 

but I could drop all three down through the subfloor in 110mm and put 1&2 into rear entry gullies? What about 3 then, the soil rising up for the upstairs bathroom needs to be just where the downstairs loo is...

[Onoff]

Isn't down and out under the thermal envelope the best?

 

(Talking with hindsight! )

[joe90]

25 minutes ago, Onoff said:

Isn't down and out under the thermal envelope the best?

 

(Talking with hindsight! )

 

I agree, I hate external pipes of all types, none on my house. 50mm outlet for basins etc down through floor and into gulley trap outside,110mm for toilets down and out to manhole.

[Declan52]

I buried all my pipework under the floor so the back of the house only has the vent stack from the toilet.

1. A 110mm pipe coming up through the floor to connect the sink and dw to.

2. Same for the utility room with one pipe serving the sink and wm.

1 pipe for your sink and shower waste. Depending on how close these are to each other you might be better off with a pipe each.

3. The downstairs toliet can go down through the floor and connect into the stack. If it's possible to connect the toliet upstairs in to the stack as it rises then happy days.

The sink and bath shower can connect into the stack as well. 

It's more how you want it to look on the outside. Having a maze of pipework at the back isn't that nice to look at when you have the chance to hide it.

 

Most of your manholes will have 6/8 different connections so as long as you use the middle flow for the toilet nothing else is going to get stuck.

[Onoff]

I had a chance to hide mine but didn't know enough about the subject to do so! I tbh didn't even fully grasp the concept of cold bridging. I was a slow realisation what I COULD have done ? Would have made future EWI easier and more effective. Got to a point a little while ago when I perhaps could have ripped out some of what I've done to bring the wastes inside but I decided against it.

[dpmiller]

7 hours ago, Declan52 said:

I buried all my pipework under the floor so the back of the house only has the vent stack from the toilet.

1. A 110mm pipe coming up through the floor to connect the sink and dw to.

2. Same for the utility room with one pipe serving the sink and wm.

1 pipe for your sink and shower waste. Depending on how close these are to each other you might be better off with a pipe each.

3. The downstairs toliet can go down through the floor and connect into the stack. If it's possible to connect the toliet upstairs in to the stack as it rises then happy days.

The sink and bath shower can connect into the stack as well. 

It's more how you want it to look on the outside. Having a maze of pipework at the back isn't that nice to look at when you have the chance to hide it.

 

Most of your manholes will have 6/8 different connections so as long as you use the middle flow for the toilet nothing else is going to get stuck.

Makes sense. Only (slight) problem is the stack. I've nowhere at the back for a straight vertical run that's compliant as the dormer for the bathroom gets in the way, I was considering teeing off the horizontal from the bathroom for an internal stack up through the roof, but there's also the option of making the other stack (at the side of the house for the ensuite) external and open.

Alternative is Durgos, and venting at the treatment plant. Anybody fancy having a look at the drawings please?

dorm093-350-Miller-R2-pdf.pdf

[MikeSharp01]

10 minutes ago, dpmiller said:

Only (slight) problem is the stack. I've nowhere at the back for a straight vertical run that's compliant 

I discussed this problem with our BCO who helped out by saying that once you get above.the highest water+ flow point the stack can stop running straight and go where you like as after that point it is only gas venting. He did not exactly say but I think he hinted at the idea of reducing the diameter provided there were Air Admittance Valves (AAV) in the system as well. So my plan is to take the stack up in the internal walls and bring it out in a Cowell on the roof. 

8 hours ago, joe90 said:

50mm outlet for basins etc down through floor and into gulley trap outside

Why can't you go direct into the 110mm pipe -what does the gully trap add if you have water traps under each sink and for things like disk washers?

[dpmiller]

I must admit I'd prefer either a trap or an air break anywhere a drain is entering the house. That way if you need to remove a sink trap for cleaning there's no chance of sewer gases entering.

[Onoff]

Doing everything internally would have meant a clean wall for me. Would have even have had knock on benefits when it comes to re-rendering this back wall.

 

 

Btw, the above is tidy compared to how it looks now!

[joe90]

2 hours ago, MikeSharp01 said:

I discussed this problem with our BCO who helped out by saying that once you get above.the highest water+ flow point the stack can stop running straight and go where you like as after that point it is only gas venting. He did not exactly say but I think he hinted at the idea of reducing the diameter provided there were Air Admittance Valves (AAV) in the system as well. So my plan is to take the stack up in the internal walls and bring it out in a Cowell on the roof. 

 

You can reduce the diameter (50mm I think) this is what I did internaly above toilet height with the aav in an airing cupboard (note, I have a stack externally on a detached garage at the highest point to vent the treatment plant)

 

2 hours ago, dpmiller said:

I must admit I'd prefer either a trap or an air break anywhere a drain is entering the house. That way if you need to remove a sink trap for cleaning there's no chance of sewer gases entering.

 

This is what my builder suggested, plenty of access to pipework is good.

 

my 110 pipe in the house rises in a plant cupboard but if in the cupboard “water fall” etc can be heard so I would suggest sound insulate any internal stack like hell (you don’t want to hear plops when in the kitchen! ?).

Edited July 2, 2018 by joe90
Edit

[MikeSharp01]

1 hour ago, joe90 said:

This is what my builder suggested, plenty of access to pipework is good

We have rodding points at the ends of the runs so we can get all the way under the house from one side all the way down to the manhole. 

[Nickfromwales]

16 hours ago, dpmiller said:

I must admit I'd prefer either a trap or an air break anywhere a drain is entering the house. That way if you need to remove a sink trap for cleaning there's no chance of sewer gases entering.

Every single rise to waste from under the house should be 110mm, without exception. Do not run even 50mm for a basin under there, ill be surprised if your BCO will be happy with that either. You should not have a trap / gulley there as it can block or even prevent rodding ( unless you have it on show and can easily get to it  ) "no ta" to that! Traps on the end of each run will suffice re smells etc, and if you vent effectively at the plant then you shouldn't get any built up gases in the run anyway. 

As you have a plant, why are you even considering getting a pipe to atmosphere from inside the dwelling? A vent to atmosphere is only stipulated if you are connected to the mains sewerage network, as each property has a responsibility to vent the sewer gasses to atmosphere to vent the entire network. AAV's ( stub-stacks ) will more than suffice in the upper rooms, and if the downstairs rooms have less than 1300mm to the invert you won't need one at all as the water pellet won't have a chance to from a vacuum when flushing. Adding anti-syphon traps to the basins or remote small-bore AAV's will suffice there. If a vacuum cannot form then there is no requirement for air admittance as it'll be doing zero. 

You should be fine teeing grey water into foul under the house, so that may help to reduce the number of pipe runs to / from the IC's. 

 

[dpmiller]

Thanks Nick, that's the explanation I need- meeting the BCO for the first time today hopefully and I don't know how switched-on he is on drainage ( fire detection is his "pet" subject apparently)...

 

All agreed on 110mm in through the subfloor then. Vented at the plant and AAVs elsewhere. I'll bring the two greys together into a back-entry gully trap as that can be positioned for the outside tap too. Sorted.

[Nickfromwales]

1 hour ago, dpmiller said:

I'll bring the two greys together into a back-entry gully trap as that can be positioned for the outside tap too. Sorted.

Needs to be "through-roddable" so grey will only be allowed to go straight to IC, or be Y branched into a foul, unless the gulley has removable caps to allow easy through-rodding. 

 

Kitchen sink and utility ( food waste ) straight to IC