View Single Post
  #1   Report Post  
Posted to uk.d-i-y
[email protected] dom@gglz.com is offline
external usenet poster
 
Posts: 2,379
Default Drainage, drainage and drainage

I've read Part H back and forth, and I'm still not sure.

I'm converting an old chapel. It's got combined foul & rainwater
drainage. Pre-existing is a 1.1m deep manhole, 2m in front of the
building, followed by a 5m run to connect to the public sewer

Also pre-existing is 4 pipes come into the manhole, 1 pipe each for
rainwater from each side of the building (at half the depth of the
manhole), and 2 pipes originally connected to ground floor toilets at
or near the front of the building (1 is still connected to a toilet,
one to a sink) right at the bottom of the manhole. All are working
correctly.

The only soil vent pipe was a branch off one of rainwater pipes,
unfortunately part of this pipe has collapsed.

Now, ideally, I'd like to route the soil stack internally up to these
existing ground floor toilet connections.

My questions:

1. For the upstairs bathroom, I'd need to have a horizontal soil
branch pipe 4m long (well actually the prescribed 18mm/metre slope)
from the loo, followed by 4m vertical drop, followed by a 1.5m
horizontal section up to the existing point were the soil pipe goes
underground. (no offsets necessary in horizontal pipework).

Is that layout likely to be acceptable to BC and likely to be trouble
free?

2. Waste water from the kitchen is a bit of a problem as the kitchen
needs to be at the back of the building.

a) One solution is a 5.5m horizontal pipe run up to the same point the
upstairs bathroom goes underground - that concerns me as a long
horizontal kitchen sink sounds likely to clog.

b) Another solution is drop the upstairs bathroom soil stack closer to
the kitchen, resulting in a short upstairs branch pipe, 4m vertical
section, and a 5.5m horizontal section (of 100mm pipe) before it goes
underground.

In this solution the kitchen would connect close to the bottom of the
4m section. I think the advantage would be the ground floor horizontal
section would clear better because of upstairs loo flushing.

The disadvantage would be if the stack blocked at this ground floor
bend and backed up - it's close to the kitchen branch - yuck. There's
a Part H rule about no connections within 750mm of a stack offset - I
guess for exactly that reason. I can however just meet that rule with
a raised area in the kitchen.

So - my question is - does solution 2a or 2b sound better?

3. A simple one this time. It would be convenient to repair that open
vent pipe to one of the rainwater branches - and for the internal
stack just to have an air admittance valve within the bathroom (above
spillover levels). I can't be sure if that complies with Part H -
though I don't see why not - whadyathink?

4. There will also be a ground floor toilet with a similar offset in
the soil pipe, shorter though, so I don't see any problem there.
However it's a 8m from the kitchen so I don't think it can be used to
solve the problem in 2b. Any ideas here?

5. HepVO - reading their docs seems to suggest use them and no AAV's
necessary - correct?

I'm also thinking that a HepVO may better protect the kitchen against
backups in pipework?