Plumbing layout advice

[Tosh]

Evening all!

After some advice wrt the pipe layout that our draughtsman has proposed. The drawings show pipework going to 2 x external stacks. I'm not particularly keen on these being external as I think they'll spoil the clean building lines. Can anybody suggest a better layout? For instance do we need the SVP that connects to the first IC as I read that the vent on the treatment plant may suffice (appreciate I may have got that wrong though).

 

We're using ICF and the thought has crossed my mind about running the stacks down between the EPS forms. Would/has anyone else done that?

 

 

 

 

 

Thanks.

[Temp]

As far as I can see both stacks are used as vertical drains not just vent pipes. For example the bath in the family bathroom connects to the left hand stack. The two WC and other bath connect to the right hand stack.

 

You might be able to move the left hand stack indoors by running it vertically in the wardrobe of bedroom 4 (bottom right corner) upstairs and boxing in the utility room downstairs. However I think this one would need to be open vented, so up through the roof.

 

Might be possible to put  the right hand stack in the top right corner of the utility room between door and wall between utility room and kitchen? Think this one can have an AAV. Edit: Actually this might be in a bit of an odd place in the family bathroom? 

Edited January 23, 2019 by Temp

[Tosh]

Thanks @Temp. Any views on running them down through the concrete core of the ICF. Must say makes me nervous wrt access if anything went wrong but maybe that risk is so low that I'm worrying over nothing. In all the houses we've lived in over the years I can't recall a single issue where we've had to access a stack but then I'm no plumber and maybe it's more common than I realise.

[Temp]

I think the most frequently reason access is needed is when you change the layout of the bathroom and need to change or add a connection to the stack.

[Nickfromwales]

If you have vented the TP then no need whatsoever for rising vents to atmosphere. I suspect your designer has done that because they would look terrible if they stopped a metre up from the branch and had AAV's on them.

As to burying in the concrete core, I imagine that would require your concrete section to be thicker there to compensate, unless, possibly, you went to galvanised steel with a decent thickness wall. You can reduce the size of the rising SVP to 80mm if there is only one WC connected, so you'd likely need to do a drop for each WC to get the smaller diameter, ( if that would help swing it with the SE ). Not something we can answer here I'm afraid.

As for specifying alternate routes for the stacks, its all a bit hopeless without sectional drawings to see what obstacles lay in the way of other routes. All academic without those.

Make sure the bath run is done in 50mm not 40mm as the run is excessively long for a bath to discharge. With 50mm you'll get an air break, with 40 probably not. Can be mitigated against by carrying the 40mm past the bath trap and up to the attic and fitting a 50mm AAV. Also, using the 50mm would mean you could connect all the baths / showers / basins into one single run, subject to fitting an AAV at the end of the run as aforementioned. An anti-syphon trap on the basin would be preferable with the smaller bore SVP's should you end up going that route. 

[Tosh]

Wow thanks @Nickfromwales for this really useful advice. All this plumbing wizardly fries my brain!

 

Can you explain what you mean by an air break? Also the pipe sizing - are you saying it's better to run in 50mm for all the bath/shower/basin or mix it up between 40 and 50mm.