"tonyjeffs" wrote in message
...
having installed a gf wc, I'm fitting a new plastic soil stack.
The old cast iron stack terminates about 2 foot below ground level, so
rather than do it proproperly, and dig out, which could be one hell of
a job, i've decided to leave a stub of 6" cast iron pipe protruding
above gl. and join the plastic pipe to it.

The plastic sleeve is slightly larger diameter, and-fits snugly over
the outside of the cast-iron, There is a 1mm gap to make watertight.
Since the cast iron from below ground terminates on the inside, there
is a lip, which is liable to catch any falling waste.

What is the best way to seal this junction which won't be accessible
again for 50 years , and taper out the lip? What sticks to plastic?
Thoughts:
Putty mixed with gloss paint; Silicone sealant; grease; Plastic
solvent glue, soft rubber fitting with circlips, other?

Brill group!

Couple of suitable O rings and plenty of Silicon Mastic.
Flaunch the base properly with cement