Modular builders moving from timber to steel
HOUSING ASSOCIATION Swan has become the ‘latest’ of a series of ‘leading exponents’ of modular housebuilding to ‘ditch’ cross laminated timber (CIT) for steel frames after the combustibles ban.
Building reported on the housing association – based in London and the south east – and its decision to ‘move to using steel-framed systems’ for planned apartment buildings, despite having been ‘one of the leading exponents of modular housebuilding based on [CLT]’. The company had set up a 400 homes per year modular housebuilding factory three years ago to deliver a 3,500 home development pipeline.
It justified its decision by noting that this was due to the government ban on combustible materials ‘in the external walls’ of buildings 18m or taller, and the news outlet added that late in 2019 L&G Modular Homes – another ‘pioneer’ of the method – and Lendlease had said they would switch to steel frames. Despite this, the outlet noted, critics of the ban had predicted it would turn the UK ‘from a world-leader’ in CLT to a ‘backwater’.
A spokesperson for Swan stated that CLT ‘remained compelling’ in terms of its ‘design flexibility, environmental sustainability, energy efficiency, fire and acoustic performance’, but that its move to use the modular system ‘was not just based on the advantages of CLT’, but on the ‘advantage from offsite manufacture more broadly’.
As a consequence of it having a ‘significant future pipeline of development’ that will include buildings 18m or higher, the company is ‘exploring a steel-framed alternative approach’, though it would ‘continue to use’ CLT for buildings below 18m, 700 of which it has in the pipeline. It also said that switching to steel would not mean ‘it had to write off any’ of its investment in its factory.
It also defended the fire performance of CLT, stating that it still believes the material is safe, and that the combustibles ban was ‘rightly intended to improve safety’, but timber ‘played no part in the blaze’. A spokeswoman noted that ‘as an industry, we welcome any change that would reduce fire and/or loss of life; however, we believe CLT is an inherently safe building material’.