Steel shines under costs spotlight
Market demands can frequently change, placing a different emphasis on the various features of buildings and other structures such as long spans, curving and sustainability. While steel construction most frequently turns out to offer the best solution, a constant market requirement is cost; with cost studies consistently demonstrating steel’s ongoing cost benefits compared to the alternatives.
Producing any cost analysis requires relevant background knowledge, so for some years the steel sector – always responsive to requests from construction professionals – has provided all the guidance needed for a robust cost analysis. A new and invigorated quarterly series of studies is now being produced (see News) called ‘Costing Steelwork’, by Aecom, the BCSA and Steel for Life.
Studies have consistently shown that steel frames have cost advantages over alternative framing solutions and deliver substantial cost benefits from features like being able to use lighter foundations, speedier construction programmes, providing spaces uninterrupted by intermediate columns, adaptability in line with changing occupier needs and offsite manufacture. On multi-storey buildings, integrating the services within the structural floor zone can reduce the overall building height or allow extra floors to be accommodated in the same building height. Little surprise then that steel frames around 70% of multi-storey buildings as well as 90% or more of single storey non-residential buildings.
The new series starts this month with a focus on steel-framed office buildings. Later studies will look at education, mixed-use, retail and industrial buildings. This first study describes the process of cost planning throughout the design stages, identifying the key cost drivers. A detailed cost model based on an actual office building is provided.
A cost comparison on this steel-framed ten-storey grade A office building in central London that was built in 2008 shows steel delivering a 7% cost advantage over a post-tensioned concrete flat slab alternative in terms of the frame and upper floors, and a 5% cheaper total building cost.
The embodied carbon content of this office development on a cradle-to-cradle basis showed steel also delivering an advantage of 11% less carbon compared to the concrete alternative.
There is also a market update on input costs with this quarter’s ‘Costing Steelwork’, which shows input costs for all industries rising at their fastest rate since 2008 according to government figures. There were significant changes for building materials in the last quarter of 2016 although the pace of growth in prices is expected to slow over the next two years and lower UK construction output will put downward pressure on prices. Aecom expects tender prices to rise 3.2% over a year from the last quarter of 2016.
Against a background of rising tender prices the focus on cost is unlikely to ease, so this new series will be eagerly welcomed.