Steel still the first choice framing solution

The chart above tracks the average cost per square metre for the steel and the concrete frame and floor options. The figures are derived from the cost study conducted by Davis Langdon and are tracked using the DTI cost indices.

In their latest survey (Q1 2008), the concrete frame and floor options cost an average of £169.92 per square metre. This is £24.83 more than the average steel cost of £145.09 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 £14.03 cheaper in 1995 whilst they represent a saving of £24.83 per square metre in 2008.

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

Building A	Composite steel beam & slab	Slimdek (steel shallow floor solution)	Long span cellular beams	Reinforced concrete flat slab	In-situ concrete frame with precast floors
Frame & floor cost (£/m²GFA)	113	142	139	162	134
Frame construction time (weeks)	7	6	6	8	8
Overall building cost (£/m² GFA)	1433	1430	1485	1488	1477
Overall construction time (weeks)	42	40	41	44	43

This chart tracks the cost per square metre for various frame and floor options for Building A: a regional office block located in Manchester.

Composite beam and slab is the most competitive option costing £113 per square metre whilst the Reinforced concrete flat slab is the most expensive at £162 per square metre.

There’s little difference in price between the other three options of Slimdek, Cellular beam, and Insitu frame with precast floors.

Building B

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)	140	170	170	189	202
Frame construction time (weeks)	13	13	13	18	19
Overall building cost (£/m² GFA)	1940	1943	1958	2035	2013
Overall construction time (weeks)	67	67	66	76	76

This chart tracks the cost per square metre for various frame and floor options for Building B: a prestige company headquarters located in London.

Again Composite beam and slab is the most cost effective framing option at £140 per square metre. This compares with £189 for Reinforced concrete flat slab and £202 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 savings of £29 per square metre.