For reinforced concrete frame structures, movement joints at least 25mm wide should normally be provided at approximately 50m centres both longitudinally and transversely. In the top storey with an exposed slab and for open buildings joints should normally be provided to give approximately 25m spacing. Where any joints are placed at over 30m centres the effects of movement (see above) should be included in the global analysis. Joint spacing in exposed parapets should be approximately 12m.