How to fill the gap between cast iron soil pipe and WC pan connector

When I did one like yours, I used some thick mastic like sealant (can't remember what, I was about 15, over 20 years ago) to cover the gap. It worked very well. So I suspect foam would work. Not so sure about plumbers mait. Silicone should work well - if you pack the joint a bit so you aim to form a skin no more that 1/4" thick.

HTH

Tim

I suspect that you are using the wrong adapter into the cast iron... We used a MultiKwik CI adapter, and for reasons we don't need to go into, I didn't cut the collar either. However, there was no smell at all. I did, however, fill the gap with mortar and sealant - but just for cosmetic reasons.

Lee

yeah. Foam it first, the silicone over the top.

All you are after is a low stress gas tight joint after all.

If replaceability is not an issue, dry it and sue car body filler :-)

Hi There

I've done this 3 times over the past 12 years in different properties

Use Silicone -It has never failed in my properties

Regards - Lightman

'Caulk' the bottom of the joint with rag torn into strips to prevent the filling material going into the pipe then top up the joint with Plumbers Mate. That is what is was made for. Do not use foam it breaks down into a brown powder when subjected to UV light i.e daylight, over the medium/long term.

Not a lot of daylight where the sun don't shine.. ;-)

My loo happens to have a window. Perhaps yours is in the 'Black Hole of Calcutta' All light contains an element of UV. It breaks down PU Foams.