Owain wrote:
Lobster wrote:
Alternatively, wouldn't simply extending the existing stack upwards a
bit to a regulation height be the easiest solution? or is there scope
for extending the stack horizontally(ish) (ie sloped up a bit) towards
the main house, then extending upwards attached to the house wall?

I don't think having a ventilating portion of the stack sloping, or
changing to smaller pipe, is allowed by B Regs, but it does seem to me
to be the most elegant solution.


Certainly is allowed. I go from 4" to 3" and run 15 meters horizontal on
mine..

Its sole function is to keep the drains at atmospheric pressure.

However beware long horizontal runs: bathwater will condense and drip
out of the end.

Fixed in my case by giving it an upwards slant of just a few degrees.

Owain