The once unfashionable district of Nine Elms in south London has undergone a transformation that has brought high-end residential developments and the new US Embassy from the north side of the River Thames. At the heart of the new-look neighbourhood is Nine Elms Point where Sainsbury’s and Barratt London have redeveloped a 1980s supermarket to create a contemporary mixed-use retail and residential scheme. Adrian JG Marsh visited Stanmore Contractors to find out how the specialist contractor has played a part in the new scheme.
“It all started when we were sent the details of a cladding package back in 2013,” said Dave Foreman from Stanmore.
That enquiry has now grown into a £32m contract that incorporates three packages: low-level cladding; internal ceilings, walls and floors; and a metal work package embracing architectural features. It’s the largest Stanmore site and due to complete later this year.
Sainsbury’s is working with Barratt London to deliver 737 new homes, a new 8,000m2 Sainsbury’s store and 3,000m2 of local shops, restaurants and office space in Nine Elms, south London. The scheme is part of the wider transformation of Nine Elms on the Southbank into Central London’s newest district, located between Chelsea Bridge and Lambeth Bridge.
The triangular-shaped site has retail outlets from ground to level three, then the residential scheme starts at level four and has apartment blocks surrounding a podium on this level. Three towers vary in height from 18 storeys on block D, rising to 27 on block K and to 37 floors on block G. Two nine and two 10 storey blocks link the towers.
Mr Foreman explained the strategy. “We wanted to make the building weatherproof as quickly as possible so that our teams could move inside to start installing the internals and complete the facade finishes in a predetermined sequence,” he said.
Design development was carried out with Barratt and its consultant Wintech to engineer the most cost-effective solution that balanced the cost, quality and programme.
As floors became available, Stanmore began installing 10,000m2 of Metsec SFS and then boarded and sealed with two layers of Y-Wall. All the joints were sealed with EPDM. The windows were installed under a separate contract by M Price.
Describing the facade finishes, Mr Foreman said: “We had three different types of cladding: Sotech aluminium rainscreen; Sto glass rainscreen; and a Sto insulated render system. A Tyvek membrane was installed on the front of the board followed by insulation, which varied depending on the cladding finish.
“On the lower floors, a helping hand bracket system was installed with 50/80mm of Kingspan. Then on the upper floors, a Rockwool DuoSlab insulation was used. DuoSlab has two insulation elements, one hard and one soft, which makes it easier to install. We then hung the Sto Ventec glass cladding panel onto brackets.
“For the glass cladding to meet the U-value and fire-rating requirements, we had to increase the thickness of insulation from 80mm to 200mm, strengthening the bracketry at the same time.”
Building regulations are now more focused on the external spread of fire, particularly on residential projects where a facade rises more than 18 metres. Building Regulations for EWI systems refer to BR 135 and the test standards for BS 8414 are fairly complex, but they are clearly essential in ensuring that buildings are protected from the risk of fire spread through the external facade system.
Stanmore has rendered facades on four blocks. There is a double board, 20mm cavity, 120mm Rockwool insulation (500mm x 1,000mm) and then render. The Sto-Rotofix, a spiral hammer fixing, was used to fix the insulation.
“This type of fixing allows the fitters to adjust the installation as they go up the building. We then applied two coats of mesh with two base coats plus a top coat,” commented Mr Foreman.
Externally the main architectural feature was a decorative 250mm x 300mm metal band running around every floor. Stanmore took the concept design and developed it in detail. Sections were fabricated off-site at its factory in south east London and brought to site for installation.
A British Gypsum system was used for the internal works. First the party walls were built to create the external line of each apartment. The first fix had to leave an open wall, and a rip board was installed at floor level to allow the screed to flow up to the floor level. In total, 56,000m² of Tarmac flow screed was poured onto Jablite EPS insulation. Once hard, the walls and MF ceilings of each home were then erected.
Mr Foreman said: “We’ve had to be flexible and cope with bad weather that did affect the build programme. But careful planning with the client and other trades has ensured we’ve kept to agreed schedules.”
The site is very tight and there’s no storage, so deliveries have to be timed with an hour slot then lifted by crane and taken direct to the workface, but some may have to go to a holding area.
The contract at Nine Elms Point has demanded a tight team approach and complete flexibility to keep it on programme. It’s due to finish in 2018 but this may need to come forward.
Nine Elms Point
Developer: Barratt Sainsbury’s Joint Venture
Main contractor: Barratt London
Architect: Broadway Malyan
Drywall, facade and screeding: Stanmore Contractors Limited
Package value: £32m
Site labour peak: 160
Site start: 2014