For many years the Editors have compiled a price book for use in the building industry with, more recently, companion volumes for use in connection with mechanical and electrical engineering services contracts and landscaping work. All of these price books take their reliability from established practice (within these sectors of the building industry), of pricing work by the application of unit rates to quantities measured from the designer’s drawings. This practice remains valid because most construction work can be carried out under similar circumstances regardless of site location. A comparatively low proportion of contract value is subject to the risks that attend upon work below ground level and once the building envelope is watertight, most trades can proceed without serious disruption from the weather.