Connecting up new waste system.....

Osma do channel covers for their 450mm chambers, although the catalogue price is rather eye watering... (£145.50 each!) Osma also offer various 315mm dia chambers, including an option for 45 and 90deg connections on one side only, part numbers are 4D933 for L/H entry and 4D934 for R/H entry.

Building control may not have an issue, (they may not even see the issue on inspection), but a build up of crud is not desirable. A, it'll soon stink, and B will eventually dislodge and possibly then block the chamber....

I know of one contractor that has recently removed a few plastic chambers at a hospital and replaced with precast concrete, in order to give a smoother flow through the chamber and prevent any further issues of this type happening.

Hugh Jaleak said:

Osma do channel covers for their 450mm chambers, although the catalogue price is rather eye watering... (£145.50 each!) Osma also offer various 315mm dia chambers, including an option for 45 and 90deg connections on one side only, part numbers are 4D933 for L/H entry and 4D934 for R/H entry.

Building control may not have an issue, (they may not even see the issue on inspection), but a build up of crud is not desirable. A, it'll soon stink, and B will eventually dislodge and possibly then block the chamber....

I know of one contractor that has recently removed a few plastic chambers at a hospital and replaced with precast concrete, in order to give a smoother flow through the chamber and prevent any further issues of this type happening.

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I'm looking at doing something similar to the op in the next year or so.
If no manhole was installed and just a T or a Y into the main drain from a stub stack. Would the join area be likely to block?

DaG56 said:

I'm looking at doing something similar to the op in the next year or so.
If no manhole was installed and just a T or a Y into the main drain from a stub stack. Would the join area be likely to block?

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No, probably less likely than if there was a manhole there. The benefit of the manhole would be if it blocked upstream or downstream from that point.

Put an access point or cap on the stub stack to allow cleaning if required, it'll be ok on a blind junction provided the main run is accessible.

Thanks for the replies and just one more thing. Are external stub stacks common and would the bc allow one?

I could core through the outside wall for the toilet waste pipe, the main drain pipe underground is about 600mm away running parallel with the wall like the ops. It's about 700mm down so not too difficult to T onto.

I'd rather have the stack in the new bathroom but I'd have to go through a concrete floor then sideways through the foundations.

If I put the stub on the outside it will make it difficult to connect the shower and basin waste. Plus it wont be the prettiest tbing to look at down the side of the house right next to the back door.

I should have started my own thread really but as my job is a similar layout to the ops I thought I'd tag onto it. Hope he doesn't mind.

External stacks are common, dont see any reason why you wouldn't be allowed. Wastes can be cored through the wall to connect at a suitable point. Ultimately it's probably going to come down to what's easiest, breaking through the existing floor, then the foundations, and then making good, including the DPM isn't the easiest of tasks, especially when a hole can easily be cored through the wall instead!

If taking the external route, you'll probably be ok with using an access bend where the pipe comes through the wall, and just drop down to the drain. No need for an AAV.