I have recently purchased a property in south London with an extension on the ground floor which contains the combi,all pipe work ie gas,mains water flow/return etc are run under the screed and the mains water has been leaking under there for years creating serious damp problems.I have cut off all services and will be re-running all pipe work but was wondering if anyone knows of a channel system that i can cut into the screed to run the pipes through rather than bury them again as this always seems to result in problems and leaks at a later date.Look forward to hearing your thought.