In Myall v Tower Insurance Ltd [2017] NZCA 561 the Court of Appeal considered an appeal about the full replacement cost of “Riverlaw” mansion payable by Tower.  The calculation of the cost was complicated by the insured area being 650m2 when the actual area was 799m2.  The judgment exemplifies the need to call appropriate evidence at a trial court.  Mr Myall appears to have been prejudiced by the choice of witnesses made in the High Court.  The Court of Appeal decided the High Court was correct to apportion the rebuild cost pro rata rather than by elements.  It also decided that Tower could use materials in common use rather than more expensive materials and that it was permissible to use timber framing with brick veneer rather than the original brick interior and exterior walls.  The finding about the walls was a legacy of the choice not to call a witness about the performance differences of the walls.  Mr Myall succeeded in having the tile costs increased because Tower had used old rates.  Tower cross appealed on the use of a 10% contingency.  The Court dismissed the cross-appeal and confirmed 10% as a standard contingency allowance.