Baden Powell Outdoor Centre, Brownsea Island, Dorset

Introduction

In 1907 Robert Baden-Powell held his first scout camp, bringing 22 boys from different backgrounds – then a radical social idea – to Brownsea Island, 230 hectares of unspoilt pine woods, heath and salt marsh at the mouth of Poole Harbour, Dorset. The Baden Powell Outdoor Centre was commissioned by The National Trust and the Brownsea Island Scout and Guide Committee to celebrate the centenary of this first scout camp. Planning consent was obtained on this very sensitive site on the understanding that the buildings would be in harmony with the landscape, low carbon in both construction and use and designed to prevent contamination of the Site of Special Scientific Interest (SSSI) on which it is built.

The buildings house a small museum telling the story of Baden-Powell, a teaching/multipurpose space, showers, wcs, washup facilities, staff accommodation and storage; they are situated on a sloping site overlooking the position of the original scout camp. The site was extremely challenging as it had no electricity, gas or sewerage utilities and was accessed from a dirt track road about half a mile from the quay on Brownsea Island. The design intention was to create an encampment of simple but poetic buildings clustered around an external activity space. The buildings touch the ground lightly and were inspired by the form of the original ridge pole tents used in the first encampment and the spirit of the scouting ideal to ‘leave the land as found’.

Building description

The orientation and form of the buildings were carefully considered to maximize the penetration of daylight for passive solar heating benefits and to minimise electrical loads. The envelope was carefully designed with openings placed only within the sheltered gable ends. The two principal pitched roof buildings lie at right angles to each other, their open gables facing a generous external timber decked activity area. Sliding folding doors in the gables - evocative of tent flaps - open up fully in summer to provide sheltered spaces with level access from the external decked area while frameless double glazing above allows abundant daylight to penetrate the building all year round and acts as a passive solar collector.

One of the principal buildings houses the scout shop, a small museum, staff accommodation and stores; the other is a teaching/multi-purpose space which faces the external deck; male and female showers, wcs and washing facilities are accessed from the gable opening on the opposite side. Smaller timber outbuildings, housing additional wcs and washing facilities, storage and wind turbine equipment, flank the site.

The deck and landscape are carefully arranged within the slope of the site to make a series of fully accessible buildings.

Materials and construction

The floors of the two main buildings and the timber deck are set at the same level for optimum accessibility. To allow the space below the timber deck and the floor cassettes to be naturally ventilated, (avoiding the possibility of damp and rot) the ground was cut away beyond the building perimeter and retained by a low post-and-beam wall. This had the additional advantage of enabling services to be installed in the void. The smaller outbuildings on the edge of the site sit on concrete rafts.

Superstructure and linings are made from pre-fabricated insulated timber cassettes held in a glulam timber frame. Air tightness was achieved in the panel components by the use of rubber seals and Camlocks. The glulam frame rests on helical steel screw pile foundations which can be removed to return the site to its original condition. The ridge beam is supported by slender timber columns which are exposed at the gable ends; the roof extends beyond and is folded down to form an outer wall, reminiscent of the traditional ridge tents used in the original camp. The problem of rainwater run-off is solved by enclosing the gutters and downpipes within the rainscreen support framework and raising the timber cladding above the line of the gutter.

The interior of the building is lined with birch-faced ply sheets while the external ‘fabric’ of the building is clad entirely in untreated western red cedar shingles and boards. Penetrations through the shingle canopy were avoided to remove risks of water damage in this exposed coastal site.

Sustainability and services

Space heating and ‘on demand’ hot water (including showers and hot water for up to 200 people per day) is provided by a 35 kW wood burning boiler. The electrical load requirements were designed out of the project and essential power loads reduced to 1.3 kW. A battery power plant was installed on the site to receive electrical power from a horizontal axis wind turbine and a photovoltaic array with back-up from a diesel generator for use when there is no wind. Waterless urinals and restricted flow wcs were installed to reduce water consumption while foul water drains to a cesspit.

Programme and construction on site

The outdoor activity centre was constructed to an extremely tight budget of £534,000 for a gross floor area of 382m² (treated floor area 244m²). The clients and architect worked closely together on all aspects of the project overcoming many challenges. Due to tight programme and cost constraints the centre was constructed in two phases over 8 months. Ground works were let to a local contractor while the detail design for the superstructure and buildings were developed with a second phase contractor specialising in prefabricated construction. Both contractors had to deal with the extreme logistical problems of bringing materials, plant and machinery from the mainland to this small island without modern quayside facilities on a sea-going barge in the middle of winter. The main building arrived in stillages strapped to articulated lorry trailers which were manoeuvred onto the island, unloaded onto agricultural trailers and hauled half a mile across a rough track to the site.