move internal soil stack

SUPERPLUMBER · 7 Nov 2008

hi all,

i need to move a soil stack thats boxed in inside a bathroom. its in the corner of the room next to the outside wall. Its boxed all the way across the wall to hide the loo waste pipe.

the customer wants to get rid of the boxing completely so i assume this means taking the pipework outside the building. As there arent any other utils above discharging into the stack, is it just a case of drilling 2 large holes in the wall (one for the bog and one for the stack to go outside) and then joining the loo to the pipe, taking the existing vertical pipe outside?

hope you can help.

SP

SUPERPLUMBER · 7 Nov 2008

heres a sketchy diag of what in on about

http://homepages.nildram.co.uk/~natkins/pipes/pipes.jpg

muggles · 7 Nov 2008

A super plumber, or even a fairly average plumber, would know the answer to this and shouldn't need to ask...and I've never seen a WC branch running uphill like that before

Richard C · 7 Nov 2008

The building regulations allow offsets in the wet section of a stack but you can’t connect a w/c or waste into the stack within 750mm of the offset; can make things difficult. You can offset the dry section of the stack however you want as it only draws air. There are also regulations on the length of unvented branches for w/c, sink & bath waste.

Difficult to see what you’re trying to do as I can’t really make sense of your sketch but I’m pretty sure poo won’t run up the stack!

SUPERPLUMBER · 8 Nov 2008

thanks, yeah the sketch is a bit sketchy, but its in 3d so the bits that look like they run uphill are the wc branches running into the distance to the main stack. i should have drawn the 3d box for the room walls

so i all i need to do is offset the upper part of the stack above the wc and take it outside, leaving the original WC branch as it was.

Richard C · 8 Nov 2008

SUPERPLUMBER said:
thanks, yeah the sketch is a bit sketchy, but its in 3d so the bits that look like they run uphill are the wc branches running into the distance to the main stack. i should have drawn the 3d box for the room walls

I spent the first 15 years of my career as a design draughtsman & have worked with drawings all my life & if I can’t understand it, what chance anyone else; I’ve never seen 3d like that before!

SUPERPLUMBER said:
so i all i need to do is offset the upper part of the stack above the wc and take it outside, leaving the original WC branch as it was.

I still don’t understand what you are trying to achieve so I have no idea; but whatever you do should comply with Part H of the Building Regulations.

SUPERPLUMBER · 8 Nov 2008

ok ive posted a new image in 3d with some perspective but as you can see im no artist.

the external wall of this bathroom is partly boxed hiding the soilpipe and wc branch. I want to remove the boxed section thats hiding the vertical pipe and move the upper part (the dry part ) of the pipe through the wall to the outside so i gain an extra 200mm in the room. I realise that there will be a stub/knuckle bend that would pass throught he wall but this will be under the new bath.

as Richard C has suggested, the branch pipe cannot run into an offset within 750mm so moving this brabch pipe outside too would cause problems. (thanks Richard)

If i leave the branch pipe inside the bathroom, currently at floor level, i can take the remaining upper part of the soil stack (above the wc connection to the stack) throuhgh the wall and outside, therefore giving me my 200mm of bathroom back.

The point of the exercise is merely to gain an extra 200mm for a new longer bath.

Any suggestions as to what i should do with the remaining upper part of the pipe...revove it completely or cap it off somewhere inthe loft (im assuming it passes through the roof at some point or exits under the eaves.

thanks for bearing with me and hope the new diag is a bit clearer

gigz · 8 Nov 2008

Could you not cut the soil low and take outside with a bend, use another bend going back to the toilet, then a bend going up with a tee (for the toilet) and vent from there ? (funny how you know what you mean to say but once its written it looks boll**ks

)

SUPERPLUMBER · 8 Nov 2008

so take the vertical soil pipe outside with a bend through the wall, then turn right back into the bathroom to the wc and vent from this end point upwards rather than the original pipe location.

are there any probs with the turds passing through a helterskelter ie out of the pan with a 90deg left turn, then back into the bathroom with another 90 left and then a 90 downwards?

if i leave the original branch pipe where it is theres only a 90 left and a 90 downwards. is this acceptable?

Richard C · 8 Nov 2008

That's better at least I can see what your trying to do now. Can't spare the time at present but will come back tommorow if you havn't solved it by then.

Richard C · 9 Nov 2008

To prevent cross flow, the take off for the new stack should be at least 200mm higher than the w/c connection. But the existing stack connection is almost certainly a swept tee so I would cut the stack just high enough above the tee to allow you to fit a bend + 10mm & dive through the wall (think about where/how your going to cut the hole BEFORE you cut the stack) with another bend the other side to take the stack on up to termination level which must be at least 900mm above any opening in the building within 3m of the open stack. Hopefully this will give you enough room the get the bath in; if not, the only other way of doing it is to move the offset to the wet portion of the stack but, for various reasons, this is usually a non-starter as you can only use 45 degree bends. Only other option is to move the whole stack to the outside but this will involve moving the drain invert as well.

SUPERPLUMBER · 9 Nov 2008

Thanks Richard.

I plan to take the dry part up and out as i only need half of the 200mm for the new bath so hopefully removing the 9.5mm plasterboard and gaining at least half of the 200mm boxing within the wall should give me enough space. Although i wont know that till i open it all up.

when i take the pipe through the wall is it ok to use two 90 deg bends since it is only a vent?

if i dont have enough room can i make the new vent at the WC end of the branch. i presume ill have to take a short section upward before i go out to stop turds nesting in the short section that passes through the wall. or would it be better to make the joint inthe middle as you suggest.

And finally do i use a weak sand cement mix to fill the gaps in the wall around the pipe or shall i use expanding foam from the inside and just repoint the outside?

Thanks again for your help Richard

Richard C · 9 Nov 2008

SUPERPLUMBER said:
when i take the pipe through the wall is it ok to use two 90 deg bends since it is only a vent?

Yes; unlike turds, air is not particularly fussy about going through 2 x 90 degree bends but make sure you have enough vertical offset (200mm) to prevent the likelihood of cross flow from the w/c.

SUPERPLUMBER said:
if i dont have enough room can i make the new vent at the WC end of the branch. i presume ill have to take a short section upward before i go out to stop turds nesting in the short section that passes through the wall. or would it be better to make the joint inthe middle as you suggest.

I’m not sure I fully understand you but there is no reason why you could not provide a new vent anywhere along the top of the existing horizontal branch out through the wall up to a suitable height; or if the foul drain system has another open vent to cater for positive pressure, provide a stub stack internally & terminate with an AAV.

SUPERPLUMBER said:
And finally do i use a weak sand cement mix to fill the gaps in the wall around the pipe or shall i use expanding foam from the inside and just repoint the outside?

Any pipe going through a wall & bridging the cavity should point downwards (outwards) to direct any water/moisture towards the outer skin. Try & keep the size of the hole as neat as you can, particularly on the outside. To make good on the inside you could use expanding foam but, for your customer’s sake, it should be neat. Personally, I would use either render or bonding plaster & then finish off with finishing plaster or filler & re-point the outside with ordinary mortar mix.

Squiggy · 13 Apr 2010

I want to do the same job, but all this talk about bends is confusing without a decent diagram.
A few questions:
1) Why would you want to go outside, then back inside again, in the bathroom?
2) Could I just take the pipes from the bathroom (upper floor) outside and then go back inside on the ground floor (below the kitchen sink just above where the internal stack goes into the floor)? See attached image.
3) If I just wanted to move the dry section initially, if the dry section is purely to vent gas, does it have to be a standard soil stack pipe, or could the diameter be reduced to enable me to put a smaller hole into the external wall ?
4) If the pipe must slope to prevent moisture crossing the cavity, what angle should the slope be?

Untitled

Squiggy
13 Apr 2010
2

JPC · 13 Apr 2010

seems u have picked a post thats 2 yrs old

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

move internal soil stack

Similar threads