Alexandra Centre

Haverstock, London, 2017

 

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Skylights take their distinctive blue colour from the water tanks atop the estate’s housing blocks 

Simon Kennedy     Download Original

  • Skylights take their distinctive blue colour from the water tanks atop the estate’s housing blocks    
  • The existing structural slab spans the site with intermediate concrete upstands and columns beneath    
  • The prefabricated timber frame was designed to straddle the upstand beams    
  • Design cues are taken from the estate    
  • The two blocks are separated by a small courtyard space that takes advantage of a concrete canopy    
  • Specialist concrete blocks above the upstands allow a suitable separation from ground level and a minimised thermal bridge    
  • The new building’s roof is designed to attenuate rainwater in order to ease the flow into the existing services    
  • With a new corridor at the centre, a new courtyard has effectively been created    
  • Alongside each corridor sits a strip of toilets and storage, a strip of classrooms and a strip of garden space    
  • The design aims to bring in natural light    
  • Site plan    
  • Ground floor plan    
  • Section AA    
  • Section BB    
  • Fixed window head and base detail section    
  • Rooflight detail    
  • Studwork wall base detail    
  • Typical fixed glazing with briese soleil base    
  • Typical window jamb    

Haverstock’s special needs facility for 16 to 25 year-olds pays its dues to Neave Brown’s celebrated Camden estate.

The modest school nestling underneath Rowley Way was part of a tripartite community provision for residents in Brown’s original design, which also included a hall and youth centre. In 2013, Camden put out an open call to update it to a dedicated facility for SEN learners.

The plan, defined by a series of concrete upstands between which sit service and drainage ‘trays’, constitutes two wings branching off a hall and kitchen at the school’s western end. These arms wrap around a central courtyard, now connected by a new corridor that allows for quicker access, as well as passive surveillance,  between the two. The southern wing is roughly twice the length of the northern one in order to house staff spaces, which sit slightly higher than the classrooms; and at the far end of this wing two new accommodation blocks have been added. These close off the eastern end of the site and with a new corridor at the centre, a new courtyard has effectively been created, in which sits a playing field that wraps around the top of the site to form teaching gardens.In rough symmetry, alongside each corridor sits a strip of toilets and storage, a strip of classrooms and a strip of garden space, each layer aligned so that the view north/south is maintained from one end of the building to the other.

The main new additions in the retrofit constitute a ‘short break’ unit sitting at the end of the two wings. It comprises two new buildings, one containing a large living space and five bedrooms, the other a one-bedroom flat with an additional room for a staff member. Design cues are taken from the estate, with the prefabricated timber frame clad in black timber and protruding skylights taking their distinctive blue colour from the water tanks atop the estate’s housing blocks. The two blocks are separated by a small courtyard space that takes advantage of a concrete canopy, which also provided a reference for the roofline of the new builds. 

Prior to refurbishment, the existing Alexandra Centre building had several characteristics of poor energy efficiency. The façade was leaky and uninsulated and the heating and ventilation systems were non-responsive and in desperate need of replacement. The design process was based on presenting the client with a series of iterative approaches, incorporating an array of different passive design options and low or zero-carbon technologies. This enabled the client to identify a solution that provides the maximum carbon saving against a reasonable economic investment.

The existing structural slab spans the site with intermediate concrete upstands and columns beneath (within the former car park below). The prefabricated timber frame was designed to straddle the upstand beams. Specialist concrete blocks above the upstands allow a suitable separation from ground level and a minimised thermal bridge
xisting waterproofing to the slab was removed and a brush-applied RIW waterproofing layer applied. The structural trays were then filled with rigid insulation and the prefabricated timber frame was installed pre-insulated. 

Counter battens and cedar cladding were applied to the outside, their black stain matching the original stain used on the college windows, doors and external screening. Vertical timber boarding widths vary from 75mm to 150mm, referencing the original proportions of the board-shuttered concrete. The change in width occurs at a horizontal datum matching the datum of the college’s concrete soffit, unifying the new building with the existing.

Internally, the structure is sealed and taped to provide an airtight layer, then battened out to provide a service void. This was covered with a double layer of plasterboard and skimmed. The new building’s roof is designed to attenuate rainwater in order to ease the flow into the existing services, which are encased in concrete columns or have been enclosed by the storage company tenants of the former car park below.  

Rooflights provide additional natural light into the circulation. Their proportion and shape mirror those on the roof of the college and they have been wrapped in a powder-coated aluminium veil, coloured blue to match the roof access units on top of the neighbouring Alexandra Estate housing.

Data

  • Begun: May 2014
  • Completed: Feb 2017
  • Floor area: 11,234m2
  • Sector: Education
  • Total cost: £5.5M
  • Procurement: Traditional
  • Address: Ainsworth Way, London, NW8 0SR, United Kingdom

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