CONTROL OF BUILDING SITES THREE TIER CONTROL THREE TIER CONTROL SITES CONTROL OF BUILDING

THREE TIER CONTROL Primary: the network of control points coordinated in all three dimensions to give a fixed overall reference framework for the works Secondary: local control points for construction or baselines established for structures Tertiary: points set out at the actual positions for construction or at suitable offset positions.

Primary Control Points These are the Master control points set out from national reference points Form a closed loop Built in redundancies for checking Set out by specialist surveyors Position and Level known Official National Survey points Primary site control points

Secondary Control Points These form the control points for setting out base lines and sites grids. Set out from the Primary control points May have associated level value

Tertiary Control Points These are the points you will be setting out Relate to construction elements Set out so dimensional checks can be made.