Arranging and venting a waste pipe branch

[phloaw]

I recently got ground floor piping extended to have drain, hot and cold in a first floor room. Only the pipes are there, but I'd like to install a sink and a washing machine as from the diagram.

https://i.stack.*********/Zngwd.png

Note that the washing machine will be at a higher level, because it will be placed on a riser about 1m higher than the floor level.
The drain pipe distance between the new sink and the lower floor sink is about 7-8 metres, while that between the new washing machine and the new sink would be about one metre.

Questions:

1) How do I arrange traps? I plan to place one under the new sink, but should it also serve the washing machine or the latter would need a separate one? And would it be wiser to buy resealing ones?

2) Should I add an aav valve, given that the branch is now pretty long (around 10 metres)? If yes, where to place it?

3) Do you see any foreseeable problem with this setup, either practical or regulation-wise? (I'm in Scotland)

Thanks!

 

[Riley]

Upsize it to 2” and fit an aav

 

[phloaw]

Upsize it to 2” and fit an aav

Thanks. Do you mean upsizing the whole drain piping starting from the stack?

 

[Riley]

I’d be tempted to run it from the stack in 2” up to the point where it bends toward the upstairs sink

 

[phloaw]

I’d be tempted to run it from the stack in 2” up to the point where it bends toward the upstairs sink

Ok, I see. Just to clarify: is your advice suggested by experience or dictated by some piece of regulation?

 

[Riley]

Well you can run 1.5” up to about 7m

 

[phloaw]

Well you can run 1.5” up to about 7m

Does the 7m limit also apply if I install the aav as you suggested? I had a look at the Approved Document H and I'm not sure about this point.

 

[Riley]

The way I’d look at it would be that the wm will have lots of cr@p going down the pipe and it has the longest distance to go. Hence I’d be upsizing to prevent blockage

 

[Ben-gee]

Riley is giving you good advice based on experience, if this exceeds any regs you may have read- don’t worry about it - the small extra cost is worth it for trouble free usage. You don’t want waste pipework on the limits of its capabilities, it will always give trouble in time.

 

[Harvest Fields]

I’d be tempted to run it from the stack in 2” up to the point where it bends toward the upstairs sink

2” sounds good mate.

 

[Riley]

2” sounds good mate.

Your Mrs must be disappointed

 

[Harvest Fields]

More than you will ever know.