The solution was to fix an exoskeleton-type primary framework over the existing glass reinforced plastic cladding to support the new windows, lightweight frame and rainscreen cladding panels. The primary framework was fixed to the concrete floor slabs of the building by bespoke brackets onto which the windows, striking new powder-coated metal rainscreen cladding panels and the secondary supports were also fixed.
Chaucer House was completed in 1965 and comprises 96 flats in the centre of Sutton. The original building had pre-cast concrete panels which had failed within 16 years and were then replaced by glass reinforced plastic (GRP) lightweight panels which by 2013 were failing, delaminating and allowing water into the building at junctions with adjoining panels and through windows. The panels were also poorly insulated and not up to current standard.
Pellings, the design, property and construction consultancy, was appointed by Sutton Housing Partnership in 2013 to carry out the feasibility report with the support of the partnering contractor Mulalley to establish suitable options available to overclad the building.
Jerry Austin, Executive Director of Property at Sutton Housing Partnership, says: “The successful Chaucer House regeneration is Sutton’s largest and most complex social housing improvement project to date. Chaucer House was a brutalist exemplar of how 1960s urban design often failed in its promise, resulting in homes that were hard to heat and unattractive to residents.
“The £13m programme of internal and external improvements, delivered on behalf of the London Borough of Sutton, has transformed Chaucer House from a 1960s eyesore to an iconic, innovative and energy-efficient building, leading the way in UK social housing. The state-of-the-art features also include fire safety systems in every home and have halved residents’ household bills. This project has not been without its difficulties and challenges, but has been delivered on time and on budget.
“SHP has a strong working partnership with building consultants Pellings LLP and contractor Mulalley and Company, building on our previous joint experience of similar works nearby at Balaam House, and the quality of works being delivered is reflected in residents’ satisfactions with the works completed,” comments Jerry.
Terry Hardy, Partner at Pellings, explains: “The challenge was to provide a solution whereby the residents could remain in occupation while the works were carried out to avoid rehousing disruption. This entailed constructing an exoskeleton-type system over the existing cladding to provide structural support for the windows which could not be supported within the existing openings.”
Once the initial feasibility stage design was completed, different cladding systems were reviewed and a powder-coated metal rainscreen cladding system was adopted to extend the lifecycle of the system and materials.
Extensive consultations took place with the residents who were involved in the selection of the colour scheme for the cladding. Six options were put to the residents by Pellings at an open evening to discuss the feasibility findings and proposed works and following a ballot they selected an option matching Balaam House, a neighbouring residential tower, also controlled by Sutton Housing Partnership.
Pellings worked with its structural engineer to produce an outline proposal for the fixing of the new cladding system and windows which was developed by the contractor. Pockets were cut through the existing panels to accommodate bespoke brackets, attached to the concrete floor slabs, onto which the new supports, panels and windows were to be fixed.
Utilising the existing GRP panel provided two purposes. The first was to provide a rigid backing for the insulation to be fixed to, and secondly to provide safe separation from the internal parts of the building so residents would not be disrupted throughout the works and could remain in occupation.
The new cladding provides greater protection against solar heat gain and has reduced the effects of condensation on cold walls internally and interstitially within the thickness of the fabric.
Terry attributes the success of the scheme to the following:
- Early involvement of the partnering contractor greatly assisted the decision-making process with regard to the installation process and access requirements.
- The exoskeleton-type solution allowed risks to be designed out or reduced by allowing flexibility with positioning of bespoke brackets.
- The exoskeleton approach enabled all residents to safely stay within their property.
- The vast majority of work was able to be carried out externally with the exception of installation of the windows as with standard window replacement works minimising disruption.
In addition to the external cladding project, Pellings acted as lead designer, town planner, contract administrator and CDM-C on the refurbishment of the £14m scheme.
Colin Watson, Operations Director for Mulalley, said: “We are extremely proud of the works we have completed, in partnership with SHP and Pellings, to totally transform Chaucer House, which is now an impressive, modernised block of flats that enhances the area and has improved residents' lives.”
Andrew Taylor, Chief Executive of SHP, said: “This project has not been without its difficulties and challenges, with many lessons being learnt along the way. It remains the most complex project of the Decent Homes Programme, but I’m sure we would agree that the final outcome is cause for celebration.”