On Sat, 9 Apr 2005 18:43:18 +0000 (UTC), a particular chimpanzee named
"Stinkoman" randomly hit the keyboard and produced:

In the en suite, I've got what I sugess is a soil stack pipe... except that
it's capped at around 1.5 metres in height. It requires its own plastboard
housing so it can be hidden away.

If I understand you correctly, this is on the ground floor. If so it
could be a 'stub stack', which is a short unventilated stack
connecting to a vented drain or sewer a short distance away. It
doesn't need a vent, as the chances of siphonage are very small.
There's no reason for it to be a 'stack' apart from it's easier to
connect the smaller branches into its side that way.

It could also have a "Durgo" or air-admittance valve on the top if
this stack is a long distance from a main drain.

Any blockage should be capable of being cleared by an access or
inspection chamber on the branch drain, or preferably at its junction
with the main drain.
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have you strayed?"