|Building sustainable homes at speed|
With the current annual housing output at one of its lowest levels in recorded history, it is perhaps a tad ironic to consider the issue of building homes at speed.
However, there is a growing need for more homes to be build and pressure to build homes that are more sustainable. This makes it an important time to consider some of the potential issues arising from the combination of innovative construction and building at speed – before the pressure really impacts.
Increasingly, new construction techniques have allowed the house-building industry to combine the benefits of building both quickly and sustainably, however house builders are still faced with the judgement about whether such systems can deliver their objectives to the same standard.
Building sustainable homes at speed: risks and rewards, the latest report from the NHBC Foundation, provides guidance on this for contractors, design teams and clients interested in innovative and sustainable forms of construction.
The report looked at a number of schemes that have had speed of construction at the centre of the design rationale and is intended to assist those involved in future schemes to maximise the rewards and minimise the risks.
Everyone involved in the provision of new homes has a responsibility to the end user of the homes we build – whether home owners or social tenants – to produce homes that are truly fit for purpose and meet the reasonable expectations of those that live in them.
The speed at which homes can be built may be a factor in both private and public sector developments, whether due to site or cost constraints. This is not a new phenomenon but may be about to be a greater one; particularly as the pressure on housing supply begins to increase – in those circumstances production may need to be swift.
Helpfully, today’s Modern Methods of Construction (MMC) systems have been developed to meet specific needs – such as improved environmental performance – but a frequent by-product is that they also enable speedy construction. MMC is not flawless though and cases of systemic failure due to the implementation of MMC has generated criticism of these measures.
Therefore clients, design teams and contractors must balance the potential risks – from fire safety to Building Regulations compliance – of such systems with their benefits – such as increased thermal or acoustice performance, or reduced community impact. Doing so effectively will help teams ensure they present durable, low-maintenance solutions which will provide a healthy internal environment for occupants over the lifetime of the building.
The risks and rewards
In Building sustainable homes at speed the NHBC Foundation analyses a range of case studies using MMC. The report considers some of the key rewards and risks of building homes quickly and sustainably, from the design phase, through procurement and into construction.
The CASPAR II project in Leeds, for example, was an attempt to develop an apartment block for the private rented sector which could be available for below market rent and still make an attractive return on investment without any subsidy. It was based on volumetric and panelised construction, which was intended to achieve greater efficiencies. While the project received critical acclaim and positive feedback from residents, defects emerged – such as to its stability and flooring – which led to a series of investigations into the construction of the building. Ultimately it was felt that the time pressures under which the scheme was developed, may have contributed to its problems.
A further example is the Castlefields Estate Regeneration Project in Runcord which is a development that uses timber frame construction. This long-term, multi-phase project was not without issue; one of which was that, due to its scale and size, the project needed to accommodate ongoing adaptation and design changes, yet an adaptable product was not easy to find for a reasonable price in the market. However over the lifetime of the project, many issues were overcome and the various phases of construction showed an increasingly sophisticated approach to closed panel timber frame construction. This was in part due to effective long-term relationships and collaborative working between contractor, client and design team, which enabled the transfer of lessons learned from one phase of construction to the next. As a result, the last phase was largely defect free.
The NHBC Foundation advises that much can be gained from the sharing of best practice learnt over many years of speed building and MMC, both within and among project teams. It is critical that at all stages of the construction, all parties employed in the project are fully integrated and the appropriate skill needs are met.
In particular, thorough planning is important from the outset, in order to take due account of potential long-term risks and maintenance issues. All component interfaces must be considered carefully at design stage to ensure correct interface solutions are devised and incorporated into the design. Finally, there must be a full review of the whole plan before pressing ‘GO’.
Social housing has seen the greatest experiment with rapid construction methods. It is RPs who have developed some of the most successful techniques for dealing with risk and have a vested interest in reducing long-term maintenance has driven a focus on reducing defects.
The advantages of building quickly are obvious: short construction programmes mean existing residents are not displaced for too long and new occupants are usually available to move in straight away. However, RPs are increasingly aware of their potential liabilities including the need to preserve funds for the maintenance and refurbishment of their existing stock.
Private developers offering new housing to home-owning customers in the UK have, in general, had a more difficult time justifying some of the risks necessary to build quickly. Ultimately, for some clients, judgements about whether breaking with conventional methods was a risk worth taking will have to wait some years. Then we can judge whether a focus on innovation and speed has produced durable and healthy homes that can stand the test of time.
Rod MacEachrane, Director at NHBC Foundation. NHBC Foundation’s Building sustainable homes at speed: risks and rewards is available to download at www.nhbcfoundation.org/buildinghomesatspeed