Kitchen drain pipes - Advice needed...

[Joe4542]

Hi guys,
I'm in the progress of re-doing my kitchen, but will soon need to do the waste pipes and could do with some advice.
I've stuck a quick pic (its crap..I know) which will hopefully make what Im saying clearer.

I had planned on the pipes being in a sort of 'T' shape with the Sink trap (with dishwasher feeding onto one of the Spigot pipes) on the right side of the 'T', the Washing machine using a standpipe arrangement being on the 'Upright' part of the 'T', and the left part of the 'T' goes through the wall out to a hopper on a drainpipe (we're in first floor flat).
Still with me???
I was going to ask what sort of 'fall' I should have on the pipes, the Sink branch being appx 80-90cm long to the t-piece, and the Wash machine branch being appx 50cm long. But then I realised that the sink trap would be about 60cm from floor level, but washing machine trap - due to standpipe arrangement would be much lower...
Would it still be poss to join the two branches at a t-piece and run one waste through the wall - even though the sink branch would have something like a 30deg fall on it, to the t-piece?? Or am I likely to have to drill two separte exits for the Sink + washing machine drains??
Obviously I'd prefer not to have to do the latter cos
1) It'll take ages to drill two holes with the core drill
2) I think it looks ugly when there are pipes coming out of the wall outside...

Any help greatly accepted, O wise ones

 

[Softus]

There's nothing wrong with running a sink waste at a 30° fall.

Clearly you wouldn't have the room to do it for much more than a short stretch, but it sounds like you're doing it merely to facilitate merging with the waste from an appliance, so that's just fine and dandy.

 

[Dan Robinson]

You WILL get gurgling though with too steep a fall. Consider coming down from the sink then going across.

The washing machine waste could always be extended and tee'd into the main run from the sink.

 

[Softus]

Hm. I can hear footsteps behind me.

 

[Joe4542]

Hi guys,
Thanks for the replies, I had a quick look at the setup last night, it doesn't seem as tho the 'drop' from the sink branch will need to be as steep as I thought.

I'm able to lift the W/M standpipe up higher than I had thought whilst still keeping a decent height on both the standpipe + keeping trap at reasonable level.

I was thinking then that I might want to put vertical vent pipes rising from each branch and joining into a AAV, to help prevent suction when one of the branches has flow in it.

But i've decided I'm probably WAY overcomplicating things , since the runs are so short each side of the branch, and the pipe on the outside wall wont be too long, prob about 1.2m dropping into a hopper. Which I'm then hoping - cos its open to air (as all drains are I suppose) will allow air back up pipe to break suction.

So I'm just gonna keep it simple and hope it all works ok - if it don't i'll be stuffed since it'll be behind kitchen cabinets.

Thanks Again