Soil stack through flat roof

That's part of it - the Screwfix picture is upside down. The normal way of doing it on a new build roof is to use a "lead slate" - it's a sheet of lead about 500 x 500mm, with a hole in the centre for the stack pipe, with a soldered lead sleeve about 150 high which you slide down the pipe. The lead is interleaved into the roofing felt and the PVC weathering collar slides down the pipe so that the splay bit covers the top of the sleeve.

Alternatively you can make a hole in the felt with criss-cross cuts to make 6 or

Peter

IANAP (plumber etc)

Isn`t this the sort of job where the regulars might normally mention a hepvo or similar air admittance valve, rather than going through the roof ?

Thanks for the replies.

An air admittance valve wouldn't work in this case as the stack goes through the roof of a single storey extension to serve the upstairs bathroom.

Peter, is this the lead slate you mentioned?

Mike

mike" wrote

Yes that's one sort. This is the aluminium version with a rubber collar which does stretch around a 110mm pipe - I'm looking at my neighbour's one like that right now. I'm not sure if they do one for flat roofs though.

What I had in mind was more this sort of thing, made of sheet lead

Peter

Yes, it used to be sold by OSMA & was known as a VariPitch Pipe Flashing, it could cope with quite a wide variation of roof slopes. There is also available an all rubber version, which is better to work with as it is all in one piece and easy to join roofing felt onto. Talk to your local builders merchant. Regards Capitol