Clients and contractors should be wary of using a “cost per square metre rate” when doing cost planning and comparison. Bert van den Heever, former Association of South African Quantity Surveyor President, says there are a number of design variables that can influence square metre rates and give a false impression of the costs involved.

“As a client, a generic cost per square metre rate doesn’t provide the detailed information that you need regarding finishes, fittings, services, site development costs, etc. There are a wide range of other building elements that also have an impact on costs and therefore quantity surveyors normally do elemental estimates to derive the square metre cost of a project,” says Bert.

Design variables also play a large role in the cost of a project. A square metre rate is calculated by dividing the net cost of the building (excluding site works, cost of land, etc.) by the gross square metres of the building or Gross Floor Area (GFA). Simpler building shapes will generally lead to lower unit costs, but even this can be misleading as a square building of 10x10m and a rectangular building of 25x4m have the same floor area but the rectangular building requires 45% more walling to enclose it.

“More intricate designs generally result in higher perimeter/floor area ratios – increasing excavation costs, drainage costs and a number of other construction related costs significantly,” says Bert.

Quantity surveyors should be hired early in the project, preferably not later than when sketch plans are being prepared by the architect. This will put clients in the best possible position to achieve the look, finishes and final touches they want and still remain within budget.

“Both the client and the architect need to be fully aware of any additional costs or savings that may arise from shape, size, circulation space and a number of other variables in the design of a building. The services of a registered quantity surveyor can help them adopt an approach that will assist the client in achieving a suitable balance between cost, aesthetics and functional aspects,” concludes Bert.

For more information, contact the ASAQS on +27 (11) 315 4140 or via www.asaqs.co.za.