How far can I run my shower/toilet outflow?

[indus]

Hi

I'm playing around with the potential internal configurations of a planned double storey extension. I am semi detached and ideally I would like to put a new shower/toilet on my attached side. This would mean quite a distance to the external unattached wall of my house where the soil stack is.

How do I figure out if this is feasible and if I can get an adequate fall?

If I can run the pipes diagonally through the shortest possible distance is is approx 13ft. If I have to run the pipes in a straight line then it is approx 20ft.

Many thanks

 

[petertheplumber12]

You need a minimum six inch fall with no sag and over that distance it would be best to upgrade to the next size waste up from 40mm. or use a saniflow. But the 4" soil pipe plus six inch fall equals 10" which you won't have.

 

[indus]

Thanks Peter.

The first pic (sorry about quality) shows the existing first floor plan. Some years ago the ensuite was created. I've measured from the shower waste to the outside wall. Even if it takes the shortest possible distance then it is a 17ft run; ie straight across the landing and underneath the area marked 'cupboards' and then to the external wall

The second pic (sorry it is quite busy and messy) shows the proposed first floor extension. The biro shows roughly where I would like the new en suite to go. If the outflow can run diagonally then it would be about the same for the shower ie 17ft and a little more for the sinks/toilets.

Since the first en suite has functioned faultlessly for over 7 years do you still feel it can't be done?

Many thanks for your help

 

[petertheplumber12]

You don't mention whether 7 years ago you ran waste and soil or just soil, I suspect it was just waste. was it 40mm or 50mm since a blockage is less likely with the larger size. also if you apply a monthly dose of waste and drain cleaner down the appliances connected to the waste pipe, you are less likely to have a problem in the future, prevention always being better than a cure. If you can repeat what you did 7 years ago then you should be ok, Just remember that showers and sinks use very little water but than same amount or more soap, It the soap being left behind to dry out in the pipe and set after each use that causes most of the problem. If you get into the habit of after showering leave cold water running for a 60-100 seconds for shower, and 30secs for sink, it will wash most of the soap suds into the outside soil pipe. Also if any tiling is done DO NOT LET ANYONE rinse sponges or put any tile adhesive or grout down the sink or toilet, I have unblocked an external horizontal run of soil pipe with a plug of adhesive all round it. and waste pipes get blocked solid and have to be replaced. Sorry its a bit long winded. And good luck.

 

[indus]

Thanks Peter.

Perhaps I don't quite understand the difference between soil and waste but there is a toilet in the en suite. Doesn't that mean that soil AND waste must have been run?

 

[petertheplumber12]

Yes a soil pipe 4"for wc, and waste pipe is 32mm or 40mm for sink basin or bath. You can always join waste into soil pipe before the soil pipe run leaves the bathroom, But where it goes under the floor for a 20ft length with a straight run even between joists if the depth of joist is 200mm and the soil pipe is 100mm then max fall over that length is 100mm or 4" that is 1:60 and less than recommended 1:40

 

[Agile]

As far as I can tell you can run it as far as you like, say ten miles, as long as you have a continuous fall and occasional rodding eyes.

Tony

 

[petertheplumber12]

As far as I can tell you can run it as far as you like, say ten miles, as long as you have a continuous fall and occasional rodding eyes.

Tony

Yes but difficult or impossible to have a rodding eye inside the property.

 

[indus]

Thanks.

Do the waste/soil pipes have to run along the horizontal axis of the joists or can they run diagonally ie do you guys cut the joists to run these pipes?

Thanks again for your help

 

[Hugh Jaleak]

Cutting the joist to fit a 110mm pipe in will leave the remaining joist about the size of a matchstick, it wont hold much up.... There are strict limits on how much may be notched out from a joist, and it wont even be enough to accomodate a waste pipe.

Looking at the drawing, the existing en suite is nearer the outside wall than your proposed new en suite. I would imagine the existing ensuite postion allows a sufficient fall to be achieved in the available space under the floor, any further and that fall may not be achievable.

Options are, run the soil parallel with the joists, (providing you can get sufficient fall), fit a Macerator ( ), lay a new underground drain under the building to a suitable position, then run a new stack up through the ground floor to new W.C. position, or move the en suite!

 

[indus]

Thanks Hugh. I think you've already mentioned this as a solution but just to be clear...

Could I run the soil/waste directly to the edge of the existing building just like the ensuite has been done. Then have the pipe coming down into the new extension and entering the ground there (and obviously connected up to drain)

That does mean however that the soil/waste pipe will run down one of the new rooms in the ground floor extension. This could be boxed in and hidden I suppose. But would I need an inspection hatch/manhole in the room for where the pipe hits the ground?

Many thanks

 

[ALEC1]

maximum recomended waste lengths from the manufacturers are 4m for 50mm and 3m for 40mm...

so on that basis a vertical soil stack has to be within 3/4m of a shower...

 

[indus]

Thanks Alec. The existing en suite must have a run in excess of the stated 4m max. Even if it is a straight route out then it must be at least 4.8m.

When the 'plumber' built it seven years ago he did say it was touch and go with the fall but was happy with the end result. And touch wood is seven years I've had no problems.

Anyway, what do you think about the suggestion I made in my previous post ie a straight run to the edge of the existing building and then have it enter the ground beneath the new proposed extension?

Thanks