Certain local conditions, which are beyond the contractor's control, may negatively influence the contractor's efficiency. This makes it necessary to apply correction factors in order to achieve a correct norm time (see DACE Labour Norms) which is representative of the actual conditions in which the work is executed.

Correction factors are applied to the standard norm times to take into account the local circumstances which are not covered in the standard labour norm.

Often the costs in the tables within this book are made up of a labour portion (in which a norm-time is estimated) and a material part (where the material costs are estimated).

The correction factor applies only to the labour part. This must be taken into account when applying. Often in the tables, the labour and material parts are given as percentage of the costs.

The correction factors apply for work activities carried out in such specific conditions.

The local ground level is assumed as 0.