I currently have an architect working for me on my latest project,
which is a proposed chopping up a of corner terrace house into two,
for resale. We've been humming and ha'ing about what to do with the
soil pipes for the two properties, given that in one of the two, this
will need installing from scratch.
Architect's proposed solution is to dig a trench more-or-less
diagonally across the solid floor of the two properties, into which we
bury the sewage pipe, to intercept with an inspection chamber in the
back yard. Hmm. Furthermore, this proposal would necessitate having
an airtight inspection chamber actually in the lounge of house B, into
which enters the soil stacks (both fully internal) from both house B
and house A. So if house A has a blockage, they'd need to ask the
occupant of house B to lift his lounge carpet and do the needful in
the inspection chamber. (FYI house A has no direct access to the back
yard, so the alternative would be dig forwards into the street, which
I'm advised this would cost megabucks; and also there's no sign of any
existing manholes out the front either).
It sounds mind-boggling to me that this scheme would be allowed by
building control; but architect - who I have to admit is very
experienced - says that apparently although they don't much like it,
it's perfectly permissible. And way cheaper than the alternative.
I'd be grateful for comments before I next see him!
| So if house A has a blockage, they'd need to ask the
| occupant of house B to lift his lounge carpet and do
| the needful in the inspection chamber.
And then finding out that Numpty Householder in B has laid laminate flooring
and skirtings over the chamber.
| (FYI house A
| has no direct access to the back yard, so the alternative
| would be dig forwards into the street, which I'm advised
| this would cost megabucks; and also there's no sign of any
| existing manholes out the front either).
Is it not possible to take a separate trench from house A under house B to
the back yard chamber without having to have the inspection chamber and
joining the two sewers?
If you are going to keep House A you should get something put in the deeds
on sale of B requiring access to be kept available to the inspection
chamber. That may affect the sale price or put off some buyers. If you're
selling both A and B you could keep quiet and a rug over it when showing
viewers round :-)
The airtight double sealed inspection covers are perfectly fine from the no
smells, no bumps in the floor point of view.
Will the two properties be up and down from each other, or back and front
with each other, or ?
In an upstairs / downstairs situation it is more common to have both loos in
the same sort of place in both houses, and the same with the kitchen areas.
This way the waste water systems run directly down through the properties
and only one outward flow is needed under the lower house and out to the
main sewer system.
If the houses are being separated as front and rear, then it does pose the
problem of pipework running everywhere just to supply them both correctly
with both incoming and outgoing water systems. So this is a bit more
intricate in its design.
When both properties are side by side, then it is a good idea to run both
systems as totally separate entities and have both systems running as
directly to the outside as possible with breaks or accesses until they reach
the outer ground traps before flowing on to the mains sewer.
To have such a system as you describe here, is to ask for more troubles than
is really needed, even in any of the situations I've described above. Both
properties should always be designed to be separate from each other until
the systems are fully exposed on the outside of the houses. Even if this
means taking the front house down and out under the floor of the rear
property, and shouldn't use rodding access or inspection points until they
emerge passed the walls.
The proposed system might be perfectly acceptable, but it would make an
awful mess if a blockage formed within the main sewer and the waste water
began rising up through the neighbours floor from the inspection pit.
This does sound eminently sensible.
So maybe I run the drain for the front house (A) totally separately
from the back one, run beneath the back house (B), without an internal
inspection chamber. House A therefore shouldn't be a problem. But
for house B; if I have an internal soil stack, against the party wall
with A, I'd need to turn it through 90 deg (or a bit more than that)
at ground level, and have it set off underground under the party wall,
under the floor of house B, in more or less a straight line, emerging
in an inspection chamber in the back yard. Sound reasonable? I'm
learning all about drains just now...! would I need, or would it be
possible to have, a rodding point in house B at the place where the
soil stack turns? Or would it be covered from the inspection chamber?
Try and keep them totally separate until they both emerge from the rear of
the houses. Then once you're outside you have free reign on what needs
doing. Try to supply a rodding access point internally beside the loo or
the sink waste systems, to stop the need for any others elsewhere on the
This is more simple than inspection pits and rodding points all over the
rest of the system. If the pipes are straight and have all the correct flow
rates, then you won't need a hell of a lot of access points on the pipes.
Back to the drawing board then ? :-))
Cue - Lobster emerges from his drawing board :-)
Having taken on board the comments from the group here, and having had
a visit from a drains company, I've moved on a bit....
It's proving a real bummer to sort this out. Trouble is that the
inspection chamber out the back is very shallow, and since the house
are built on a slight slope, with the se about 6-9" lower than the
front one, there's no way I can get enough fall on an underground soil
pipe connecting it to the front house. I'm advised that taking it out
the front onto the Queen's highway would be likely to cost 6-7K, so
that's a non-starter. So... the latest plan is to fit a communal,
internal soil stack built against the party wall of the two
properties, which would need only a very short, separate,
near-horizontal soil pipe to connect to the upstairs toilet in each
house. This stack could be built into a cavity formed to the side of
the chimmney breast, on the party wall, and the pipe then travels
underground to the inspection chamber out back. There would be enough
fall for that.
This again has the disadvantage of poo from house A travelling down a
soil stack built into house B. However, I can't see any need for A to
worry B about blockages as the whole horizontal run under B can be
rodded from the external inspection chamber. Presumably this is the
sort of arrangement which must exist in multi-occupation blocks of
flats? I wouldn't have thought the stack itself would be prone to
blockages would it, surely it's the horizontal runs?
Spose I could run install two separate stacks in the chimmney breast
space, with two parallel soil pipes running under B to the chamber,
but not sure if that would really achieve anything.
Again, comments much appreciated!
Sounds great to me, but I would ask you to allow rodding access from the loo
connections as well as from the outside chamber. Just a TEE with a cap end
on it, to allow a rod to be inserted in that end of the system as well.
You'll be amazed at how much this would help prevent having to disturb both
dwellings if the unfortunate should happen.
Run with it I say.
Good advice. IME the bottom of a drop pipe is a popular place for
blockages - esp if the brickie has dropped mortar down the pipe.
A slow bend here [not an elbow] is a good idea too.
Just fix the Air Admittance Valve in such a way that it can be taken off
As I've been fortunate enough never to have had occasion to need drain
rods; how much access room would I need to provide in line with the
TEE connection by the loo? I realise that drain rods come in 3'
lengths, but how much do the things bend? Or is there a coiled
version of a drain rod that would do the needful if required?
And if the blockage is just downstream from the internal inspection
chamber, it fills up, and when you open it, don't fancy trying to get the
carpet clean. Not to mention the problem of putting flooring down to start
The BR approved document
states "Access points to sewers (serving more than one property) should in
places where they are accessible and apparent for use in an emergency.
Examples of suitable locations include, highways, public open space,
unfenced front gardens, and shared or unfenced driveways."
Even if you did it this way, I think there would have to be something
written into the deeds to give the other houseowner right of access, which
I can see being offputting to potential buyers.
That's a little unfair - never considered myself as "greedy property
developer". I'm very much a diy-er; I intend to most of the work on
this project myself. I have a regular 9-5(?!) desk job and will be
doing it all in my spare time; furthermore this is the first time I've
ever bought a property to 'develop' rather than live in.
I've been posting here on-and-off for donkey's years - damnit, it was
me who ran the RFD for creation of this ng in the first place! I do
hope people won't object to further posts from me about this project
over the coming months...!
I don't see you advertising any wares or creating lease contracts for the
buildings development authorities, so I have no objection at all in
answering your questions.
Good luck with it, I say. And I hope you get loads a money on letting or
Just make sure your DIY stands up to building control inspection. :-))
I have an ispection chaber in the middle of my kitchen. When the drain blocked
the drain rod equipment goes throught the house, and we all know where it has
before - not nice.
Your problem would appear to be that people like me would not buy either house
knowing what they would have to do if the drains blocked. I reckon it would
both the properties.
Your other option (a total bodge) is to fit the chamber, when building inspector
goes, concrete it over, then the buyer has no idea its there, you get the best
both worlds and are long gone when the new owner finds out. If I was the new
owner and found out, I would not be happy.
On 7 Nov 2003 09:58:31 -0800, firstname.lastname@example.org (Lobster) wrote:
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