Adding upstairs wc and installing manhole

[deano]

I'm looking for some detailed info, preferrably some diagrams for the following...

House has downstairs wc, directly below upstairs bathroom, which has bath and sink but no wc. Downstairs toilet drains down into floor, out through back wall (underground) and into sewer pipe. There is no inspection chamber in the garden.

I need to add a toilet upstairs via an external stack. I'm also thinking of connecting the downstairs toilet to this new stack, out through the back wall and blocking off the current underfloor connection. This is mainly because adding new pipework (for both toilets) would be easier than trying to tap into the existing underground one that goes to the downstairs toilet (I think?).

I then intend to excavate down to the existing branch (in the garden) and install an inspection chamber, at that junction, while at the same time, renewing the branch that goes into the sewer.

So, I will renew everything from the sewer, back to the house, to supply the old and new toilets (and possibly kitchen sink and dishwasher).

Should I decomission the current branch into the sewer, from the house, and block it up with cement, making the new branch on a straight bit of the sewer (away from the current branch)? Or should I make use of the existing branch and put an IC in at that location?

Or, would it be possible to do this without using an IC and just connect the new stack onto the existing branch at the back wall, before it goes under the house and into the downstairs wc?

I'm familiar with the technique for tapping in to a sewer and adding a branch, but I could do with seeing some diagrams that depict the system, dimensions and materials etc. (Haven't yet found anything on Google... not sure on the correct search query string(s).

I'd be grateful for any advice.

cheers, deano.

[Roger]

The message from "deano" contains these words:

Where is the current stack and why is it not practical to plumb the upstairs WC direct into that?

[Owain]

One of the manufacturer's sites (eg Osma?) probably has catalogues with lots of diagrams.

Owain

[David Hansen]

On 25 Sep 2006 01:38:38 -0700 someone who may be "deano" wrote this:-

Borrow a book on drains from the library then, as well as looking at manufacturer's web sites.

Do the pipes from these go through the wall and into a hopperhead, from which there is a pipe leading to a gully?

How close to the toilet outlet is the gully I assume takes waste from the bathroom?

Do you intend to move the existing toilet far from the current location? If not, why not leave it where it is so that you have a working toilet while the work is being done?

Is there any reason to renew all of this?

[nafuk]

Sounds like a good idea. I would leave the current toilet alone so it can be used (even if the house ins't currently lived in) and try and bring the new upstairs stack down by the side of it so that it can be tapped into once the upstairs is completed. This will obviously need a new pipe going through the wall for the downstairs toilet and a turn connecting into the new stack. You might want to check this is all within code as I'm not a plumber, but have done something similar at my own house.

[deano]

There is no stack! The downstairs loo goes down into the floor and then, AFAICT is connected straight into the underground pipe at the back of the house. There must be a stack somewhere, maybe for more than one dwelling, but I couldn't see one.

[deano]

Thanks, I'll check those out

[deano]

Yeah, the library occured to me... now I just need the time to get there.

Good question, I didn't think to see where the u/stairs bath and basin drained to! I think I need a revisit, with that at the top of the list.

As above... need to re-assess this, I have no idea where the u/stairs waste currently goes!

No, the d/stairs loo will stay exactly where it is. Just need to plan where to put the new stack and branch it into the main sewer, far enough away from the existing branch.

Only that a house 2 doors down has done similar work and there, they seem to have changed the downstairs loo to drain into the newly installed stack for the upstairs loo, rather than leaving it to drain into the existing set-up, as in this house. I did wonder why they might have re-routed the downstairs loo into the new stack... any ideas?

thanks, deano.

[David Hansen]

On 27 Sep 2006 12:34:57 -0700 someone who may be "deano" wrote this:-

Entirely normal with downstairs toilets and "two-pipe" drainage.

There should be a vent pipe somewhere.

[David Hansen]

On 27 Sep 2006 12:46:14 -0700 someone who may be "deano" wrote this:-

More money than sense?

Unless there is a problem with the existing drains I would tend to leave them as they are. The only thing I might be tempted to do is remove the existing gully and replace it with an easy bend which leads to a new stack serving the upstairs bathroom. That involves the minimum of digging, assuming the drains are deep enough at that point for the bend.

As with all drains, Building Control are a useful source of information.