Cost Comparisons

Below is an introduction to the topic of Cost Comparisons. You can also search for your specific topic using the Search box at the top of the page or click on any of the following keywords and phrases – Comparison – Steel versus Concrete – Choice of Material – Building A- Building B – Composite frames.

Historically, cost comparisons have been independently calculated between various material choices for construction solutions. The choice of steel has always been prevalent because of, among other things, cost. Costing exercises have been brought up to date, and despite a perception that steel prices has narrowed the comparative gap between material choices, this is not the case. Steel has maintained its status as cheapest option, and indeed has widened the gap.

Steel still the first choice framing solution

The latest cost comparison study of quarter 4, 2010 for commercial buildings continues to re-affirm that structural steel framing solutions are faster to build and more cost effective than reinforced concrete alternatives and have been so since the first study in 1993.

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.

Click here for a description of the study

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.

Building A	Composite steel beam & slab	Slimdek (steel shallow floor solution)	Long span cellular beams	Reinforced concrete flat slab	Post tensioned ribbed concrete slab
Frame & floor cost (£/m2GFA)	94	132	108	153	118
Frame construction time (weeks)	7	6	6	8	8
Overall building cost (£/m2 GFA)	1125	1143	1157	1191	1166
Overall construction time (weeks)	42	40	41	44	43

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.

Building B	Composite steel beam & slab	Slimdek (steel shallow floor solution)	Long span cellular beams	Reinforced concrete flat slab	Post tensioned ribbed concrete slab
Frame & floor cost (£/m2GFA)	108	145	128	175	169
Frame construction time (weeks)	13	13	13	18	19
Overall building cost (£/m2 GFA)	1573	1588	1584	1668	1633
Overall construction time (weeks)	67	67	66	76	76

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

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.