I have dry lined walls on an external wall and am planning to conceal hot and cold cooper feed pipes to a handbasin in the dry lining. There will be no new (active) cement compounds used, merely plan to cut pipe run into plasterboard and with the gap behind it, there will be sufficient room to conceal the pipes which will be fixed properly in place and lagged. Is this ok from a regs perspective or do the pipes need to be in conduit or any other considerations.