Simple rules for cutting chases in walls
Vertical chases should not be any deeper than one third of the total wall thickness
In a cavity wall, vertical chases should be no deeper than one third of the thickness of the skin they are being placed in
No chases, horizontal or vertical, should be made back to back
Horizontal chases should be no deeper than one sixth of the thickness of the wall thickness
In a cavity wall horizontal chases should be no deeper than one sixth of the thickness of the skin they are in
Chases must go from a to b in a straight line and diagonal chases should not be used
Common sense – If the chase is too deep it will impair the stability of the wall.
If chases are back to back, there is no wall!
It must always be remembered that the person doing the electrical work may not be the same person who wants to hang a picture on that wall or put a serving hatch or window in it. All chases therefore should be sensibly placed to give everyone a chance of working out where they are in relation to lights, switches, sockets and appliance points.