What went wrong at Oxley Woods?
Report for housebuilder Taylor Wimpey shows ongoing technical defects affecting landmark factory-built housing scheme in Milton Keynes
In 2005, the then Labour government launched a competition which aimed to revolutionise housebuilding. The Design for Manufacture contest, backed by deputy prime minister John Prescott and dubbed ‘the £60,000 house’, was supposed to be major housebuilders’ answer to the problems of providing low-cost, sustainable homes for the masses through the use of ‘modern methods of construction’ (MMC).
Among the winners, which included designs by HTA, Sheppard Robson and PCKO, Rogers Stirk Harbour + Partners’ (RSHP) Oxley Woods scheme stood out as the most radical. The 122-home development in Milton Keynes was constructed from timber frames and clad with colourful panels and it was down to its ‘thorough-going attempt at innovation within the all-too risk-averse conventional housebuilders market’ that the development won the 2008 RIBA Manser Medal.
But just seven years since its completion, in May 2007, Oxley Woods is suffering a catalogue of issues linked to moisture ingress and damp, according to a damning report seen by the AJ. The document, produced by consultancy GHPC and commissioned by housebuilder Taylor Wimpey, follows complaints by Oxley Woods residents, 16 of whom have lodged claims with the scheme’s insurer, the National House Building Council (NHBC), which is now assisting with a ‘remedial programme’.
So what exactly are the problems and what could have caused them? And what could such serious post-construction issues mean for the future of factory-built homes?
GHPC’s report, based on surveys of three of the properties, following a desktop review, says ‘loose cladding panels had been highlighted across the development’ and homes are suffering from ‘water leakage problems’ and ‘double glazing failures’. It adds that water ingress is causing rot to supporting timbers, balconies, roofs, window junctions and the boarding and frame behind the cladding.
‘There is likely to be wet and dry rot and fungal infestation behind the rainscreen of each dwelling, due to poor detailing and poor construction,’ the report states.
The survey report avoids pointing the finger at specific members of the construction team whether it be architect RSHP, developer Taylor Wimpey or MMC contractor Wood Newton.
However, it does say that ‘poor detailing and poor construction’ has caused widespread water ingress across several Oxley Woods homes. Specifically, it points to major problems with the cladding, saying that inappropriate screws, a lack of fixings and missing damp-proof membranes have all contributed to the issues. The cladding was designed and installed with a minimum ventilation gap of 20mm, yet NHBC standards suggest a 50mm cavity, the report adds.
It also reveals that the bespoke timber windows are ‘generally suffering from excessive moisture content’ and says ‘poor workmanship in the window construction, installation and a lack of post-installation maintenance’ have all contributed to the problems.
Main defects at Oxley Woods according to GHPC report
- Rainscreen cladding panels becoming detached
- Damp-proof membranes missing from windows and behind cladding panels
- Supporting battens and structure suffering from dry and wet rot
- Coping detail to the top of the parapets found to be discharging water run-off into cavities saturating the boarding, supporting battens and timber frames
- Windows suffering from excessive moisture
- Loose roof coverings
- Leaks and excessive condensation build-up around rooflights
The survey’s findings are not the first time problems at Oxley Woods have been reported. Issues raised by early residents ranged from leaks to faulty doors and windows and, in one case, ‘severe water ingress’. In 2009 these issues were attributed by RSHP to ‘defects in manufacturing and construction’ (AJ 04.07.13) and were described as ‘teething problems’.
The AJ found a reluctance by all parties to discuss the extent of the problems at Oxley Woods or their causes and implications. RSHP declined to comment on the report [though has since released a statement, see below] while Taylor Wimpey would only say that it was ‘preparing a programme of remediation works for all affected homes’ to restore each ‘to the condition which the customer expected at the time of purchase’. The AJ also made efforts to speak to residents, but none wished to comment.
Wood Newton went into liquidation in 2011, but the firm’s former director Gary Hibbard says: ‘We were aware of problems to some homes, but have not seen the report so cannot comment fully. However, the problems were all related to window and cladding detailing. We are not aware of any issues with the structure of any houses on Oxley Woods, or with any other structure built using the same technique. All details were given Building Control approval by the NHBC in February 2007.’
So what could the example of Oxley Woods mean for MMC in housebuilding in 2014? After all, RSHP itself is currently gearing up to deliver another MMC housing scheme – a 36-unit development in Stratford for Newham Council, though this will use standard window and cladding details, rather than the bespoke methods used at Oxley Woods. Linda Inoki, chair of Xplain, a grassroots campaign for better architecture in Milton Keynes, believes the development on her doorstep will encourage housebuilders to stick to tried-and-tested techniques.
We need an exemplar development to show prefabricated homes can be a pleasure to live in
She said: ‘We need an exemplar development to show prefabricated homes can be a pleasure to live in. Oxley Woods obviously isn’t it. It’s very sad, because it sends housebuilders back to the view that you have to stick to traditional house building methods.’
David Birkbeck, one of the original judges of the Design for Manufacture contest, was more circumspect, saying of Oxley Woods: ‘In the other competition schemes the architects had more instruction and moderation by the housebuilders they were working for. The schemes [by HTA, PCKO and Sheppard Robson] used more standard details – details that were already proven to work.’
However, he dismissed the idea that the problems at Oxley Woods might halt innovative construction techniques, saying this would just mean construction ‘standing still’. ‘Innovation is risky,’ he added. ‘You can’t have innovation and no mistakes’.
How much comfort this will be to Oxley Woods residents, who paid upwards of £200,000 for their homes, is anyone’s guess.
Statement from Rogers Stirk Harbour + Partners
‘This was a design and build project with Taylor Wimpey and Wood Newton responsible for the final detailed design and implementation from a Rogers Stirk Harbour and Partners (RSHP) concept design. There have been some issues with the final design details with water ingress in some of the houses on the scheme. We understand that these are being addressed by Taylor Wimpey and modifications have been made to some windows and seals.
‘The design of Oxley Woods was inspected and approved by the NHBC and is under their guarantee. The residents are very supportive of the design concept and it is disappointing that these issues have materialised in the built product. We know that the residents are keen to commission their own independent study and we will support them where we can. Taylor Wimpey has not issued the report to RSHP, and therefore we are not in a position to comment on its contents, but we understand it states the issues are fully resolvable.
‘The Homeshell and Y:Cube concepts are sound and Insulshell (the panel manufacturers) have been developing their product in the intervening years. Y:Cube is a volumetric system and both are very different in terms of construction and design to that used at Oxley Woods.’