Connecting up new waste system.....

[Adam182]

Hi Everyone,

Currently trying to get my head around connecting up all the new downstairs wastepipes and what would be the best method.

I've laid out a rough plan and was hoping someone could help me join the dots.

All wastes will run under the suspended floor (I have about 3ft of space underneath) and exit underground at the external wall (exiting above ground will likely not allow for sufficient fall). The main waste run is roughly a foot deep at the inspection chamber and has a good few foot of fall by the time it reaches the main road.

Any feedback is much appreciated.

 

[Ian H]

The waste pipes would be better fixed between the joists and run outside above ground level into a gully.

Toilet to a stub stack with an air admittance valve.

 

[Hot&Cold]

Whats the distance between dishwasher to external soil pipe ? and same for sink

Looks like an island sink is being considered

 

[John D v2.0]

What's wrong with an island sink? Do it in 50mm and ensure a good fall. If you can put a dishwasher or washing machine on it will flush through the pipes well. We have that setup and it's the only horizontal run that doesn't have a WC upstream

 

[Hot&Cold]

What's wrong with an island sink?

Nowt,as long its all fitted correctly. Unlike the new (bank holiday diy special) install i saw this morning

 

[Hugh Jaleak]

I'd connect the WC directly to the drain, and would fit a chamber on the junction into the existing drain. Use a plastic chamber with 90° and 45° inlets, WC and gulley can connect at the same point with only one connection into the drain needed. Run the appliance wastes to the gulley, sink and washing machine on one 40mm pipe, dishwasher and basin on another. Fit an anti vac trap on basin.

 

[Adam182]

The waste pipes would be better fixed between the joists and run outside above ground level into a gully.

Toilet to a stub stack with an air admittance valve.

The problem is not only do the joists run parallel with the main waste i'm aiming for but I also have 75mm celotex inbetween the joists aswell so there is no longer a gap. Apologies for not stating this.

Whats the distance between dishwasher to external soil pipe ? and same for sink

Looks like an island sink is being considered

Distance is about 4metres for both, we did consider and island but due to it needing to be so small we've opted to go for an L shape instead.

What's wrong with an island sink? Do it in 50mm and ensure a good fall. If you can put a dishwasher or washing machine on it will flush through the pipes well. We have that setup and it's the only horizontal run that doesn't have a WC upstream

Did you send yours below ground aswell or did your exit the external wall above ground?

I'd connect the WC directly to the drain, and would fit a chamber on the junction into the existing drain. Use a plastic chamber with 90° and 45° inlets, WC and gulley can connect at the same point with only one connection into the drain needed. Run the appliance wastes to the gulley, sink and washing machine on one 40mm pipe, dishwasher and basin on another. Fit an anti vac trap on basin.

Is this what you mean? would this only work if I could exit above ground? or is there a way to tap into gulleys from the side? also would I also need an anti vac trap for the sink?

Thanks for all the replys everyone its much appreciated.

 

[John D v2.0]

Did you send yours below ground aswell or did your exit the external wall above

Goes under the floor into the void as 50mm, has an elbow, then drops a few inches into the 110mm drain joining the downstairs WC and the other wastes. That then goes on to an outdoor manhole. The drains are quite shallow, as is the floor void, so the run as a whole doesn't have room for any drops.

 

[Hugh Jaleak]

Your diagram is spot on. Wastes can go into the gulley from the top, or use back inlet connection if below ground level. Risers can be used to bring the grid to finished ground level if the gulley itself needs to be set slightly lower.

 

[Adam182]

Goes under the floor into the void as 50mm, has an elbow, then drops a few inches into the 110mm drain joining the downstairs WC and the other wastes. That then goes on to an outdoor manhole. The drains are quite shallow, as is the floor void, so the run as a whole doesn't have room for any drops.

Interesting, I would have to extend the waste from the toilet in order to connect all the pipes into, how have you gotten around venting?

Your diagram is spot on. Wastes can go into the gulley from the top, or use back inlet connection if below ground level. Risers can be used to bring the grid to finished ground level if the gulley itself needs to be set slightly lower.

Thankyou, would It create a problem if I were to swap so the Sink joins with the Dishwasher, and the Basin with the Washing Machine? it would just make the pipe running a little easier due to some of the locations of supporting brick walls underneath the floor.

 

[John D v2.0]

Interesting, I would have to extend the waste from the toilet in order to connect all the pipes into, how have you gotten around venting?

No venting needed on all the ground floor stuff as the pipe is big enough and the fall correct for the air to come back along the same pipe. But the upstairs showers/basins have an aav at the top of the 50mm stack. The main vent is from the stack on t other WC.
Not saying all that would work for you, that's just ok for us

 

[Ian H]

Your diagram is spot on. Wastes can go into the gulley from the top, or use back inlet connection if below ground level. Risers can be used to bring the grid to finished ground level if the gulley itself needs to be set slightly lower.

Would you run from the subfloor in 4" into the back of the gully?

The 4D900 gullys I like can be drilled out to make a back or side inlet and can be easily raised with a bit of 6" pipe.

 

[Adam182]

No venting needed on all the ground floor stuff as the pipe is big enough and the fall correct for the air to come back along the same pipe. But the upstairs showers/basins have an aav at the top of the 50mm stack. The main vent is from the stack on t other WC.
Not saying all that would work for you, that's just ok for us

I wonder if this would work if I used a T at the Toilet to extend it further back to accept the other wastes, It would mean I wouldn't need to add a gully on the outside.

 

[John D v2.0]

I wonder if this would work if I used a T at the Toilet to extend it further back to accept the other wastes, It would mean I wouldn't need to add a gully on the outside.

You can't use a t under the toilet, it has to enter in line with the flow. So a Y branch would be better, or similar.

 

[Hugh Jaleak]

I wonder if this would work if I used a T at the Toilet to extend it further back to accept the other wastes, It would mean I wouldn't need to add a gully on the outside.

No, I'd advise against it. Have seen it done, but there is always the risk of solid matter from the toilet going the wrong way and causing a problem, The waste runs need to be kept as short as possible, no more bends than necessary and provision for cleaning made when installing. All have the potential to block with soap/grease etc, and sorting that out is never pleasant.

You could always take Ian's suggestion, bring a section of 110mm pipe in under the floor from the back inlet of the gulley, and connect the wastes to that via bosses.