Newham Council’s housing company is swapping the primary structure of a dRMM-designed scheme from timber to concrete in the wake of post-Grenfell changes to building regulations
The RIBA Stirling Prize-winning practice’s mixed-use project The Brickyard, a redevelopment of an empty car park on the junction of Barking Road in East Ham, was approved in May 2018.
But now the council’s Red Door Ventures housing company says it has undertaken a ‘high-level review’ of dRMM’s 11-storey design following ‘corporate changes’ at the top of the company and to ensure the scheme meets the government’s updated building regulations.
In December 2018, the government brought in a ban on using combustible materials in the external walls of blocks of flats above 18m (six storeys).
The ban does not prevent cross-laminated timber (CLT) from being used in buildings above the height threshold but does stop it from being used in the external walls. This has prompted housing associations and developers to abandon CLT on high-rise projects.
A planning statement sent to Newham Council explains: ‘A high-level review of the consented scheme was undertaken to understand how the design could be amended to improve the circulation, massing and appearance alongside changing the primary structure from cross-laminated timber to reinforced concrete frame due to changes to the Building Regulations.’
Studio Partington, the architect brought in by Red Door Ventures to revise the scheme, said the change was driven by ‘efficiency’ and that retaining the CLT frame would have meant ‘unnecessary complexity’.
A practice spokesperson said: ‘If the CLT frame was to be retained in the design of the building this would have meant introducing three structural systems (one for retail areas, substructure and cores; one for internal apartment walls and floors; and one for the external walls) leading to unnecessary complexity.
‘The change to a reinforced-concrete frame provided a number of structural and cost efficiencies allowing for improvements elsewhere, for instance an increase in the number of affordable homes.’
But Alex de Rijke, director at original architect dRMM, said it was ‘perfectly possible’ to comply with the building regulations by placing the timber structure ‘inboard of the façade zone’.
He said mass timber structures were ‘inherently safe’ in a fire and should not be confused with toxic composite cladding.
De Rijke also challenged the idea that the CLT frame made the scheme more complex. ‘dRMM’s original scheme was conceived in CLT not only for the enormous environmental benefit in terms of embodied carbon, but also for structural efficiency,’ he said.
‘Residential units above commercial premises require a transfer structure to avoid columns compromising open-plan shops; the lighter weight of a residential timber structure requires significantly less foundation, transfer and ground-level concrete structure than an all-concrete scheme.’
‘It is perfectly possible to build engineered timber buildings and comply with the new legislation by placing the timber structure inboard of the façade zone. Complexity is not necessary or inevitable. In reality, the practical construction advantages of prefabricated timber buildings over in-situ concrete are legion, including faster build speed, fewer deliveries, smaller workforce, fewer trades, a safer process and healthier working conditions.’
Studio Partington, however, said the practice has measured the overall volume of concrete in the scheme and it works out at 1750 cubic metres less than dRMM’s original scheme.
Newham drmm partington
A spokesperson for Newham Council said there were a ‘number of factors’ in the decision to swap the frame, which it argued will improve the quality of the flats and increase the number of affordable homes.
‘Building safety and regulatory compliance are essential with all our developments. Changing from a CLT structure to a concrete structure enabled us to improve scheme viability and thereby increase the number of genuinely affordable homes on site in line with Red Door Venture’s new corporate direction.’
’The change from CLT allowed us to achieve an additional floor within the taller element without increasing the height permitted by our planning permission. This change coupled with adjustments to core locations enables us to reduce the overall height and mass elsewhere across the site.’
The 98 flats in the scheme were originally intended to be for the Private Rented Sector (PRS) however the company is seeking to drive up the affordable homes across all its projects.
Another 185-home dRMM scheme for Red Door, which will see a former town hall building in East Ham turned into housing, is also being partially switched from PRS to Affordable Rent.
Peter Barber Architects’ seven-flat shared equity scheme on Romford Road is also being changed over to London Affordable Rent.
Studio Partington’s full comment: Studio Partington were appointed by Red Door Ventures to undertake a full review of the consented scheme. The aim of the review was to investigate opportunities to improve the quality of the new homes and change the tenure mix being provided, introducing affordable homes. The original scheme was entirely for the rental sector.
Recent changes to regulations do mean that the use of a CLT panel in the external wall of a tall residential building is not possible. If the CLT frame was to be retained in the design of the building, this would have meant introducing three structural systems (one for retail areas, substructure and cores; one for internal apartment walls and floors; and one for the external walls) leading to unnecessary complexity. The change to a reinforced concrete frame provided a number of structural and cost efficiencies allowing for improvements elsewhere, for instance an increase in the number of affordable homes.
town hall annex 2016