In an earlier contribution to this discussion,
Peter Hemmings wrote:

Hi,

I moved into a house with a side extension garage which has a flat
roof on top of about 6 feet of tiles set at 45 degrees. The original
flue outlet from the side of the house has been cut just below the
flat roof and diverted through a vent in the tiles.
The roof space is a bit cluttered with the pipe and I thought I would
fit a vent valve and remove the pipe across the underside of my roof.
I was told some time ago that I could only do this if there was a
"free vent" elsewhere on the property.
Could someone confirm this is so and if so why is it necessary?

Thanks

I assume you don't really mean "flue", but soil stack.

The sort of valve that you can use to terminate the stack in the roofspace
is a one-way affair, which lets air *in* but not *out* - otherwise you'd get
nasty smells! You can only use these when there is another vent, which is
open to the atmosphere - within a certain distance (but not necessarily
within your property), to prevent pressure build up.

I'm sure others will quote chapter and verse. Otherwise, consult a Building
Inspector at your local council's Building Control department. They'll tell
you what you can and can't do.
--
Cheers,
Set Square
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