Modernisation work a late 1960’s extension has necessitated repositioning some existing central heating pipes & provide new spurs for a conservatory radiator. The under floor pipes in the existing extension were buried in a 100 x 100 pre-formed concrete duct below a 30mm floor screed & surrounded by some sort of loose, granulated material which looks a bit like used cat litter! I assume this provides insulation & allows for expansion movement of the pipes but what is it? Should I refill the existing duct with this before concreting over or can someone advise a modern equivalent material?
Also, the 2 new spur pipes are not contained within a duct at present; what is the accepted practice for burying pipes in concrete floors? Should I form a new duct & backfill similar to the existing or is it acceptable to just wrap the pipes in Deso tape & concrete them over?
Also, the 2 new spur pipes are not contained within a duct at present; what is the accepted practice for burying pipes in concrete floors? Should I form a new duct & backfill similar to the existing or is it acceptable to just wrap the pipes in Deso tape & concrete them over?