I have a 32mm waste pipe from a sink joining a 110mm vertical soil pipe with a strap on boss. The joint is leaking between the boss face flange and the soil pipe surface. The joint is under the first floor floor panels, in a corner against blockwork, between joists, there is another strap on boss adjacent plus hot and cold water pipes - access is extremely limited!! I can't see or feel the strap on tightening fixture to adjust. Is there a sealant that I can put over the joint? would a long jubilee clamp (if I can thread it through!) plus a sealant secure the leak? The sink waste can be very hot so I am assuming some flexibility may be required. The soil pipe continues downstairs and is boxed in, the leak has damaged the carpet and removing the box-work and coving has damaged the decoration so I am looking for a good long term secure fix! Any advice welcome, thanks, John.