Under JCT SBC/Q 2016 how large must an error in quantities be before being corrected?

Clause 2.14 permits the correction of errors in description, quantity or omission in the Contract Bills and thereafter adjustment of the Contract Sum under clause 4.3. Question is how large should an error in quantity be before it becomes correctable. If there is a 2m2 error in 200m2 of brickwork would this lead to an adjustment of the Contract Sum?

My starting point would be to look at the guidance in the relevant SMM for the work type but also look at the context of both the particular work item and the project as a whole.

I believe what you are looking for in this type of adjustment isn’t really a straight remeasure but a review of the rate applied because, due to the correction, the work has changed in type so either a bulking discount should be applied or a difficult or limited working supplement is applicable. Context will therefore be paramount.

As a (very) general guide I would look at anything under 5% being unlikely to create a change.