Waste pipes and heights

[SB2023]

Hi all

Having invested time reading every entry on this magnificently useful thread (50mm pipe has been drilled into my head), I thought I would post my own questions as I am still confused on a few points as I start on my own first fix waste.

 

I have two main questions based upon my shoddy powerpoint drawing, I am hoping someone can help.

1. In my image below, can I connect pipes like this, is that what the entry points on the sides are for? The toilet will go immediately into the front of the 110mm soil pipe (assuming the frame can pipe straight out the back) which goes immediately into the ground. Washing machine and utility sink will come in from the left and toilet basin from the right.

2. In the second image (in reverse), upstairs, I have toilet, basins and shower in a line before going into a different soil pipe. Can the shower drop in below the waste pipe as I have shown as I am not sure how I would get the required fall otherwise without digging up the concrete slab first floor. Or do I have to make sure I have a 200mm gap below the soil waste for the 50mm drain?

   1.

2.

 

Thank you!!

 

[Thorfun]

Thanks for the lovely comments about my thread. I wish I could help you but I do really still not know much! I’d have been lost without the wonderful help from the knowledgeable folk on here. Hopefully someone can help with your questions. 
 

I did try reading the building regs on the subject of waste but got quite confused! If you’re smarter than me (wouldn’t be hard!) then maybe you can try and glean some knowledge from them. 
 

best of luck!!

[SB2023]

I felt like I was on the journey with you @Thorfun ha! but super helpful! 

The regs were a start but I struggled a little converting them to real life in those situations above. I think the shower waste in the second picture is a no-no, but I would like to avoid digging up concrete!

[crispy_wafer]

opposing connections below need 200mm I believe, connections at 90 are not entirely in the no connection zone so I believe are permissible.

 

I knew I'd seen it somewhere on my hunt for rules - here it is.

 

Technical_Bulletin_7_2014_Cross_Flow.pdf

 

I'd wait for others to comment though...

Edited January 25, 2024 by crispy_wafer
polypipe doc.

[SB2023]

great simple document, thanks!

 

[marshian]

Stupid question can you not reverse the layout of the room so the toilet is closest to the soil stack then basins then showers

 

In my simple mind that means the toilet waste is always going to get additional "washings" from the flows from shower and basins

[SB2023]

Definitely not a stupid question!

I hadn't actually considered that, a good idea. We would need to move the door entrance (none of it built yet), maybe turn it into a slider. The HWC isn't where it is shown anymore.

 

[Thorfun]

But if you move the shower further from the soil stack won’t you need to dig more concrete out to get the fall to it from the shower trap?

[marshian]

3 minutes ago, Thorfun said:

But if you move the shower further from the soil stack won’t you need to dig more concrete out to get the fall to it from the shower trap?

 

With just water waste (showers and sinks) you don't need a huge amount of fall I've always used 1 in 40

[SB2023]

13 minutes ago, Thorfun said:

But if you move the shower further from the soil stack won’t you need to dig more concrete out to get the fall to it from the shower trap?

Oh yeah... That's a very good point.

[marshian]

6 hours ago, SB2023 said:

Oh yeah... That's a very good point.

 

I assume the shower tray already has to be on a riser to save digging?

[SB2023]

3 hours ago, marshian said:

 

I assume the shower tray already has to be on a riser to save digging?

Yes the floor build up will be about 80mm off the slab so I will need some framing.

I am wondering if I can find a tray that lets me have the drain towards the left and then I get closer to the hole we will have in the slab and drop down lower into the soil pipe...

I might have to just give it a try!