Woodland Classrooms, Belvue School, Northolt

Introduction

Belvue School is a secondary school for children with severe learning difficulties and a range of other needs. Its site, in Northolt, west London, lies next to a small patch of woodland over which the school has been given custody. With a few trees, shrubs and undergrowth, the woodland is small and scrubby, but for the students, many of whom come from nearby blocks of flats, it represents their only glimpse of nature.

The school needed more classrooms and were due to be allocated a couple of Portakabins. But the head teacher decided that her students deserved better. She considered that a more imaginative solution could be found in a design which would link the new classrooms and the woodland, to provide a richer and more stimulating learning environment for her students. She raised the money for the new classrooms independently so that design direction was not hidebound by institutional limitations.

The brief was to create 150m2 of extra curriculum space with a domestic quality and intimate scale. Studio Weave worked with the school to develop a ‘collective narrative’ with the students, to open up imaginative ways of engaging with the woodland just outside. They set up a series of story writing and design workshops; these identified the boundary between playground and the woodland as the border between familiar school territory and the ‘magical mysterious world beyond’, with the new classrooms acting as the gatehouse and gateway to this magical world.

There are two timber-lined classrooms, connected by a central covered open space. One classroom, Cosy Lounge, is used for workshops but can also be a calm and private sensory space when required. The other classroom, Sociable Kitchen, acts as a café with a food preparation area and space for group dining; it aims to encourage and inspire students to take on extra responsibilities and develop independent living skills. Both classrooms have full height glazing on the woodland side so that students can become aware of the changing weather and seasons. The timber-lined covered space between the classrooms, Messy Barn, is for outdoor learning, whatever the weather.

The gables are clad with cedar boards and fitted with large cedar sliding doors which open to give access to the woodland, or close to create a more intimate space. Smaller doors are set within them to give secondary access.

For Studio Weave, timber was the clear choice both for construction and cladding, reflecting the woodland context and with the ability to create a building with a domestic and nonthreatening quality.

The use of timber

Je Ahn, project architect, explains: ‘We wanted to create a low tech building, using as much craftsmanship as possible, and as robust as possible for a timber building’. The two classrooms and linked semi-outdoor space are all constructed of timber and together create an elegant and distinctive form – three pitched roofs with curved glulam rafters which rise to raised clerestory lanterns running along the ridges.

The roofs are covered with standing seam zinc. The gable walls are clad with PEFC-certified western red cedar boards, laid vertically; they were carefully selected for the correct moisture content and secret-fixed to battens and counterbattens to act as a rainscreen.

The walls, of highly insulated timber studwork, are a series of box-like forms which create storage spaces and alcoves for sitting spaces, as a recess for a woodburning stove in the Cosy Lounge, for kitchen appliances in the Sociable Kitchen, and as storage cupboards in the Messy Barn.

The classroom entrance doors are at the sides of the Messy Barn; the lower-ceilinged timber alcoves create an intimate scale at the entrances which open up to the curved pitched roof classrooms, filled with light from the clerestory above.

In the classrooms the curved 45 x 145mm glulam rafters are lined internally with 12mm birch ply sheets, bent on site to form the curve and fixed to the glulams to create a diaphragm. The ply ceiling was finished with Osmo Polyx Oil with clear intumescent coating.

At the base the timber structure is fixed to bespoke stainless steel feet which in turn rest on helical piles. Piles were used to reduce the building’s impact on adjacent trees; to accommodate the slope of the ground and to ventilate the timber frame, the building is raised off the ground on the north side and accessed with steps.

The structure

Andrew Trotman, project structural engineer and director of Timberwright, describes the structure:

‘Timber frame was proposed as a lightweight and sustainable construction material that could be realised on site using predominantly manual labour.

‘The building consists of a timber frame suspended floor and superstructure, supported clear of the ground on small diameter bored piles. The floor and wall panels were specified in standard treated softwood sections that could be fabricated and assembled on site, where access for panels made off-site was not feasible.

‘Open panel constructed walls provide stability in both directions via the external sheathing; the woodland gable ends are predominantly glazed/open and the stability is maintained in this transverse direction by additional discreet ‘buttress walls’ in the fit-out zone of the external and internal walls.

‘The roof structures are supported via structural ridge beams in the form of timber frame box trusses defined by the roof lantern zone, spanning between the gable ends. These trusses in turn support the upper end of the concave glulam rafters. This structural system eliminates any lateral thrust at the foot of the rafters onto the wall plates, and the associated need for internal ties across the roofs.

‘The roofs and floor plate act as structural diaphragms via OSB/plywood sheathing to provide adequate racking stiffness on plan.

‘The glulam rafters and box truss components were manufactured off-site in whitewood by Lamisell. The weight of each box truss was such that it could be erected using Genie hoists onto the prepared wall supports. Exposed framing in the glazed gable ends was fabricated in fresh sawn UK Douglas fir.’

Sustainability

The building is almost entirely constructed of PFC and PEFC-certified sustainable timber. The stack effect created by the curved pitched roof form allows the classrooms to be entirely naturally ventilated. The classrooms are thoughtfully orientated to maximise sunlight and avoid overheating. They are also fully wheelchair accessible.

Every effort was made to involve the students in the design and construction of the building. The classrooms are fitted with shelves where students can display the crafts they have made and the sink splash-back is of tiles made by the students.

Studio Weave worked with a forest management specialist to develop a woodland strategy to ensure good maintenance and sensitive upkeep of the woods. The woodland strategy aims to bring benefits to the wider community, by improving biodiversity in the area and addressing the effects of the busy A-road that runs along the back of the woodlands.

Awards

Winner, Wood Awards, Education & Public Sector, 2018

Winner, RIBA London Award 2018

Winner, RIBA London Client of the Year 2018

Winner, AJ Architecture Awards 2018: Project of the Year

Completion Date:

October 2017

Building Type:

School

Location:

Northolt, West London

Architect:

Studio Weave

Structural Engineer:

Timberwright

M&E Consultant:

Arup

Main Contractor:

IMS Building Solutions

Timber Supplier:

T Brewer, Lamisell

Timber Elements:

Roof and wall structure, internal finish, doors and windows, cladding

Timber Species:

FSC- and PEFC-certified Canadian Western red cedar, Douglas fir, birch ply

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