Soil pipe in way of flat roof joists! Help

[Kido44]

I am having a wall removed, due to a kitchen extension, and a flat roof fitted on the extension.
The soil pipe from the toilet runs in the way of where the steel will be going and the flat roof joists.
How can I get the soil pipe down through the steel, and the joists, without the fall being to great.
I will be getting a plumber out but I'm worried this is going to cause a major problem.

I have provided a pic, and I'd appreciate any help.

Thank you

//www.diynot.com/network/Kido44/albums/

 

[Kido44]

......

 

[ServiceNumpty]

New Soil Stack Time.

 

[ServiceNumpty]

What I don't understand is how your architect missed it. You do have plans don't you.

 

[Kido44]

What I don't understand is how your architect missed it. You do have plans don't you.

Yes, thats what the roofer said today.

I'm happy to replace it but is it possible to drop it down it between the joists?
That will mean a section of it boxed in at ceiling level in the kitchen?

 

[ServiceNumpty]

Yes can't see an issue as long as you have the right fall, might be an idea where it connects to the main stack to place an access branch. Your plumber will be able to advise you.

 

[Kido44]

Yes can't see an issue as long as you have the right fall, might be an idea where it connects to the main stack to place an access branch. Your plumber will be able to advise you.

So it will be below ceiling level in kitchen? Boxed in?

 

[Hugh Jaleak]

It'll have to be replaced, trying to do anything with the existing cast iron would be difficult and expensive. If the vertical section can remain in the same position then should be possible to drop it between two joists to bring it underneath ceiling level, then run it across under the ceiling, boxed in.

If the new section can be run within the levels of the steel, then shouldnt be too major an issue to box it in, you'd be covering the steel if the pipe wasnt there anyway. Alternative could be to move the drain, bringing it under the new extension, then run stack vertically on the same plane as the exit from the pan, and create a pillar in the room to disguise it.

 

[JeffT]

If where the soil pipe passes out through the wall is above / below the joist and its just the section which falls which becomes progressively in the way, then an additional joist spanning the new extension walls could be placed outside the sloping section to pick up the joists. the ceiling / roof could then span from this back to the man wall above / below the pipe. it all depends on the depth of the joist & its location relative to the pipe.

if the pipe, where it passes through the wall, would pass through the joist then pipe replacement is the easiest option.

Remember to insulate the pipe wherever it ends up to reduce the acoustic effect.

J