"Tony Bryer" wrote in message
...
In article 5kqsc.79$Vp5.3@newsfe2-win, Terry D wrote:
As I should have realised, it's just an easy way to save a few quid on
the
build costs.

Several months ago, I visited a show house which had an exterior soil
stack.
Strangly, when questioned, the sales representative, although very
friendly,
had absolutely no idea as to the reason for this. I'm still looking for
an
answer, apart from cost.

It may just depend on the builder's preference. If it goes outside you've
got
all those holes to make through the external walls followed by making good
afterwards but you can then defer putting in the drains until the houses
are
almost finished. If you want internal soil stacks you need to do all the
drainage at the outset and it's not unknown for it to be disturbed by site
traffic (ready mix truck parked on manhole etc)

The old cast iron pipes would crack after a freeze. This is highly unlikely
to happen on a plastic stack. Water inside may freeze but it will not
fracture the pipe. Also it takes a real heavy freeze to block a drain.
Although a trickle leak down it will build up and block the drain.

Having the stack on the outside also acts like a large thermals bridge.
They can suck heat out of the house. Best having them inside using HepVo
traps and/or a Durgo valve to prevent penetrations through the roof.