Following built-quality problems at PRP’s Orchard Village housing, practice partner Rick Burgess calls for robust expert monitoring in Design and Build projects
Design quality is the residential sector’s Holy Grail, but while there has been a seminal improvement in housing design over the past decade, this has been largely at pre-planning stage. The quality of design implementation has failed to keep up.
The principal method of procuring housing in the UK remains Design and Build (D&B); its primary aim being to provide clients with a single point of recourse – the contractor – for both design and construction at a fixed, preagreed price.
In D&B projects, the architect and design team work with the client to achieve a planning approval. The planning information is then enhanced by the architect, who produces additional drawings to target important areas of the design. The tender documentation dictates the required level of detailing and materials to maintain design quality, with less critical areas left for the contractor.
Who is responsible for build quality?
Although contractors are responsible for construction quality, this isn’t as clear cut as it sounds. The contractor shoulders responsibility for all risks under D&B, but makes allowances for this within its costings. So in order to be more competitive and win tenders, a contractor’s focus may shift from quality to reducing costs, for example by pricing for lower-quality products.
We have seen a dramatic decrease in the availability of suitably skilled tradespeople
But build quality can also be directly affected by a number of issues:
Firstly, most contractors have very little direct labour. They rely on the installation of separate works packages by their appointed subcontractors. These subcontractors will invariably have tendered on the same and often sparse information from the contractor, thus compounding any cheapening of the build quality.
Secondly, we have seen a dramatic decrease in the availability of suitably skilled tradespeople. Moreover, poor installation by inadequately skilled workers can easily be overlooked in the absence of a robust monitoring regime. This is exacerbated by the industry-wide loss of experienced site agents and foremen – the key personnel responsible for checking tradespeople’s work – as result of the last economic downturn.
Finally, and perhaps most importantly, invariably there is insufficient independent monitoring of build quality by a client’s representative. Many D&B projects are overseen by an employer’s agent and project managers who often hail from a quantity surveying background with a focus on cost and time. Assurance of the quality of completed work is therefore primarily reliant on self-certification by the contractor. But what if a contractor’s team is not suitably skilled and experienced or not focused on quality?
As the architect on a D&B project, we rarely have the opportunity or authority to prevent such defects
Like many architects, we at PRP have had recent direct experience of post-completion defects, usually arising from a failure to follow the architect’s detailing. Defects have included missing DPCs, ineffective waterproofing, incorrect roof constructions, disconnected below-floor ventilation, incomplete airtightness membranes, and missing insulation. It is a cause of frustration that, as the architect on a D&B project, we rarely have the opportunity or authority to prevent such defects.
In addition, there is little client comfort in the inspection or sign-off by the building control officer and/or the post-contract insurance inspector (eg NHBC). These inspectors only visit the site at the construction stages that satisfy their own criteria.
Projects procured under D&B should be assessed by an independent inspector appointed by the client, who is both suitably experienced (architect or clerk of works) and has the authority to condemn poorly executed work, or work that doesn’t meet the required quality.
Off-site manufacture (OSM) can raise the quality of the final build product. It offers a high level of control over quality in the factory, assembly by skilled operatives and strict quality control checks at key stages. But careful attention is needed to ensure standards don’t drop when an OSM product is brought to site and installed – particularly when not by the manufacturer.
Light at the end of the tunnel?
While we shouldn’t overlook D&B’s benefits in terms of cost certainty and a single point of responsibility for the client, clients need effective ways of mitigating potential pitfalls. This should include investing in enhanced design information that ensures all parties commit to an agreed quality outcome at tender stage, supported by robust independent monitoring of work.
Something that is beginning to gain traction is the retention of the original design architect
PRP is working with an increasing number of clients who appreciate the benefits of enhanced tender documentation. Such clients are essential if we are to have any hope of improving the quality of design and construction. Something that is also beginning to gain traction is the retention of the original design architect, to work with the contractor, maintaining continuity from concept design through to construction.
Alternatively, the architect can be retained as a ‘design guardian’ – a role PRP has carried out for a number of clients. The design guardian vets the technical design by the contractor and ensures design quality is maintained.
The government is also encouraging improved quality standards, and references design quality in its recent white paper on housing supply.
As architects, we have a part to play and should, together, constantly seek to improve our process and product to raise the quality of residential construction. Instances of substandard construction quality need to be consigned to the past.
Rick Burgess is technical partner at PRP