Rating Manual section 4: valuation methods

Part 3: practice note 2 - revaluation 2010 - the contractor's basis

The Valuation Office Agency's (VOA) technical manual for the rating of business (non-domestic) property.

Costing of External Works as a Percentage of Building Costs.

Additions for external works should normally be made having regard to a costing of the individual external features within the hereditament (such as services, roads, paths, car parks etc). Where this is not possible or practical, the following table may be used to provide guidance as to an appropriate percentage of building cost to apply to reflect externals. The table is intended as a guide only and the figures do not necessarily reflect the minimum or maximum additions, which may be appropriate in individual circumstances.

In particular the following percentages should only be used:

  1. a) Where no other specific guidance is available for a particular class of property in the form of a practice note or Rating Cost Guide entry, or
    1. b) Where surveys are not sufficiently detailed to permit costing of individual external features.

Suggested percentage addition

"Low" build cost "Average" build cost "High" build cost Building ratio*/description
3.5% 2.5% 1.5% Town centre or island site typically with a 90% or greater building ratio, no more than a small yard or garden area, and either no car parking, or a very limited number of spaces within the hereditament.
7.5% 5% 2.5% As above, but typically with an 80% to 90% building ratio, limited staff parking and landscaping, and with some boundary fencing.
10% 7.5% 5% Site typically with 50%/75% building ratio, some landscaping around buildings, secure boundary fencing, adequate staff parking, and limited general parking within the hereditament.
12.5% 10% 7.5% As above, but typically with 25%/50% building ratio, landscaping around buildings, secure boundary fencing, adequate staff parking and general parking within the hereditament which falls short of full requirements.
17.5% 15% 12.5% Site typically with about 25% building ratio, landscaping around buildings, secure boundary fencing and adequate parking within the hereditament for staff and all other users.

*e.g. a building with a total GIA of 5,000m2 on a site of 10,000m2 would indicate a building ratio of 50%.

The above percentages may be interpolated to allow for circumstances, which differ from given building criteria.


  1. The percentages shown are for external (site) works only and do not include the basic site value.
  2. Higher percentages are shown for low build cost buildings to reflect the fact that (for a given total cost of external works) the lower the cost of the building, the higher will be the percentage of building cost those works represent.
  3. In some instances extensive external works (and/or very low cost buildings) will mean that external works percentages will be greatly in excess of the figures shown above.