The High Court (Davidson J) decision in Emmons Developments New Zealand Ltd v Mitsui Sumitomo Insurance Co Ltd & anor [2019] NZHC 277 considered whether cracks to a concrete slab were “damage” under a material damage policy; what was required to remediate the cracks, and what the insurers were liable for when repairing insured earthquake damage also affected undamaged property.  The buildings at issue were Rydges and the adjoining carpark.  Each was damaged, but not destroyed in the February 2011 earthquake.  The policy required restoration of the damaged portion of the property to a condition substantially the same as, but not better or more extensive than, its condition when new.  There was agreement that there were pre-earthquake slab cracks and slab sagging.  The insurers accepted that exterior cracks of .3mm and interior cracks of .4mm were damage.  Insurers said that the insured had to prove damage crack by crack.  This required proof that the earthquake caused the crack and the crack involved physical change to the extent that it impaired capacity with engineering consequences compared with its pre-earthquake condition.  The Court decided that the policy required assessment of portions of the property- not crack by crack.  So experts had to look at portions of the property ie. there may be parts with multiple cracks of lesser width.  This required engineering judgment.  The Court said that repair of each crack in the top horizontal concrete element required epoxy injection over the full length of the crack.  Standard industry practice is to repair cracks of widths .2mm and above.  Pre-existing cracks suffered loss of strength as a result of being worked during cyclic loading.  A degree of loss of aggregate interlock was probable and the cumulative effect may constitute impairment so as to be damage.