Provisional quantities should be avoided whenever possible, as rates can loaded in the hope of quantities increasing when remeasured. In addition pricing remeasured work, when quantities have changed, can be challenging.
NRM2 now gives guidance on how remeasured provisional quantities should be priced.
'Where the variance between the ‘provisional quantity’ and the ‘firm quantity’ measured is less than 20%, the rate tendered by the contractor will not be subject to review. Where the variance is significant (i.e. 20% or more), the rate can be reviewed to ensure that the rate is fair and reasonable to both the client and contractor.'
Duncan Cartlidge FRICS