Commercial cost study

The figures are derived from the cost study conducted by Davis Langdon and are tracked using the Department for Business, Innovation and Skills (BIS), formerly BERR/DTI, cost indices for 2 typical commercial buildings;

• Building A - Regional office block in Manchester
• Building B - Prestige company headquarters in London.

The chart below tracks the average cost per square metre for the steel and the concrete frame and floor options for Buildings A&B combined.

At Q1 2011, the concrete frame and floor options cost an average of £155.03 per square metre. This is £35.60 more than the average steel cost of £119.43 per square metre.
In comparison with 1995, the cost differential between the average steel and concrete options is actually wider today. The steel options were £12.10/m² cheaper in 1995 whilst they are £35.60/m² cheaper in 2011.
The cost of a frame and floor is a relatively small part of the total cost of a development. However, the selection of a steel frame reduces timescales and has a beneficial effect on other major variable cost items such as foundations, cladding and services, leading to significant cost savings for the overall project.

Building A - Regional office block in Manchester
The table below show figures from the most recent Davis Langdon update of Quarter 4 2010.

The chart below tracks the cost per square metre for various frame and floor options for Building A.

Considering Frame & Floor costs only, it can be seen that composite beam and slab is the most competitive option costing £94/m² whilst the Reinforced concrete flat slab is the most expensive at £153/m². There is less of a difference in price between the other three options of Slimdek, Cellular beam, and Insitu frame with precast floors.

When considering Overall Building Costs, Slimdek is cheaper at £1143/m² than in-situ concrete frame with precast floor at £1166/m², despite being more expensive when considering Frame & Floor costs alone. This is due to all steel options having a much lighter superstructure than the concrete options, resulting in significantly lower foundation costs.

Building B - Prestige company headquarters in London

The table below show figures from the most recent Davis Langdon update of Quarter 4 2010.

The chart below tracks the cost per square metre for various frame and floor options for Building B.

For Frame & Floor Costs, composite beam and slab remains the most cost effective framing option at £108/m². This compares with £175/m² for Reinforced concrete flat slab and £169/m² for Post tensioned ribbed concrete flat slab.
The steel options of Slimdek and Cellular beam also have significant cost savings for this building. In comparison with the cheapest concrete option, both systems offer considerable savings of £24/m² and £41/m² respectively.
The steel options also offer significant reduction in the overall construction programme of 9 or 10 weeks compared to the concrete options.