Friday04 September 2015

Chelsea Open Air Nursery classroom by Friend & Company Architects

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A need to provide more classroom space and a stronger connection to the garden has led to the creation of a new “tree house” mezzanine in a children’s nursery in London.

Tree House Classroom
Friend and Company Architects
Chelsea Open Air Nursery School, Glebe Place, London SW3

The new space has been designed by Friend & Company Architects and employs a lattice of CNC-cut steel beams, leaf-patterned infill panels and glass balustrade openings to create a dappled “glade” effect when the sun shines through rooflights.

Established in 1928, the Chelsea Open Air Nursery School is situated in Glebe Place off King’s Road, and was founded to provide an environment that encourages exercise and free play as a means for young children to learn.

Friend and Company classroom section

Friend and Company classroom section

The new £250,000 tree house classroom is located in a double-height space, originally an artists’ studio built in 1917, and replaces an existing smaller mezzanine floor.

The structural arrangement of the mezzanine consists of flat-plated serrated profiled primary beams and criss-crossing secondary beams welded together to create a steel lattice or web like structure. For simplicity’s sake, the frame had to be fabricated upside down.

An 8m-long steel plate was sourced to avoid the need for butt welds in the primary beams, although once cut, residual stresses in the plate caused deformations that had to be straightened during fabrication.

The steel structure of the new mezzanine is made of the criss-crossing beams, resembling the “branches of a tree”.

Source: Structure Workshop

The steel structure of the new mezzanine is made of criss-crossing beams, resembling the “branches of a tree”.


The structure was assembled first in a workshop and then taken apart and transported to the site where it was erected and bolted together. The secondary beams were arranged to accommodate sheets of birch plywood for the classroom floor and in an interesting architectural flourish, the underside of the new mezzanine reveals the criss-crossing steel beams, or the “branches of a tree”.

The beam design allowed for a simple clamp plate detail to be developed around the perimeter to accommodate the balustrade. The balustrade alternates between panels of structural glass, employed to draw in daylight and to allow views below, to birch plywood panels.

Meanwhile the soffit to the new classroom resembles a tree canopy, comprising large triangular (the largest is 2.4m) pieces of fireproof MDF with a delicate William Morris-inspired oak leaf pattern CNC routed into the material. The triangular pieces were recessed into the openings on the underside of the structural steel lattice and fluorescent lights have been recessed into the panels.

Friend and Company's new classroom for Chelsea Open Air Nursery School

Source: Ioana Marinescu

The soffit to the new classroom resembles a tree canopy, with an oak leaf pattern CNC routed into the MDF panels.

The kit of prefabricated laser-cut structural components was designed by the architect using 3D design and bim manufacturing techniques.

A 3D cad model was used to exchange information between the architect and the engineer and involved digital patterns to which all elements were laser cut including beams, clamp plates, lugs and stair treads, balustrade and soffit panels.

The classroom structure including the stair and fit-out took two weeks to install.


Client: Chelsea Open Air Nursery School; Architect: Friend & Company Architects; Structural engineer: Structure Workshop; Steel fabricator: Stewart Noel; Steel laser cutter: Cutting Technologies; Soffit panel CNC cutter: Wup Doodle; Lighting supplier: Architectural Lighting Works



Readers' comments (3)

  • zecks_marquise

    eh? the pictures must not do this justice because there seems to be little relationship between a canopy concept and the reality. To me the structure is fussy and seems to offer no benefits over a conventional arrangment.

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  • flow

    Good effort I say. I think most practicing architects can appreciate the hard work required to pull off even the slightest of non-conventional 'flourishes'.

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  • SomeoneStoleMyNick


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