The cost estimates prepared during the planning and design phase are the responsibility of the design professional, unlike those prepared later by the contractor as part of the tendering process. As we have noted, they are a part of the schematic design and design development stages. As the design becomes more refined, estimates are expected to be more precise. Whereas the owner can only be assured that the cost estimate during preliminary planning is within, say, 30% of the eventual cost, an estimate as close as 10% may be possible after the completion of design.
