Collge Pierre Smard Bobigriy

Iworia Buczkowska

Subject | Ever since her studies in Gdansk and Paris it has been the endeavour of the architect Iwona Buczkowska to create buildings and interiors characterised by variety and vitality using standardised building units. In doing this she shows a preference for unusual shapes, in particular for sloped and curved surfaces. She has devoted considerable time and effort to the arch as a basic element of construction.

In 1989 she won the first prize in a competition for a secondary school for 600 pupils to be built in Bobigny near Paris. The prize-winning idea was that of a basic structure of identical wooden arches from which the various floors were suspended, thus leaving the ground floor to a large extent free of columns and posts and creating greater translucency and increased mobility. Used purely as tension elements, the supports on the upper floors were kept extremely slim.

Government rulings for French school building construction are exceptionally rigorous. For access to interiors, for instance, they permit only straight corridors of minimum surface area. In this case, however, the architect attempts to break away from this concept and for the various functions to provide differing qualities of space and lighting, while at the same time creating a lively configuration of unusual room combinations and shapes. With these highly individual ideas she won deserved recognition: the school was built in 1994.

Design | The school administration offices and entrance lie alongside the road leading to the school. Set back at ground level, they create a varied and partly covered-over widening of the sidewalk, leading to the main entrance in the form of a semi-public forecourt. From here one can see into the lower-lying central courtyard. The big entrance hall directly behind the offices offers a first impression of the concept systematically applied throughout the whole of the building: wooden arches with suspended floors. From this hall an amply dimensioned circular arcade leads around the inner courtyard to the various units; first to the round-domed library, then to the classrooms and beyond these to the science and technical labs and, finally, to the hall. Beyond the labs is the sports area and, next to the college entrance, the art rooms.

Location

Collège Pierre Sémard, 85 rue Pierre Sémard, 9300 Bobigny, France

Client

District Authority of Seine-Saint-Denis. Delegated to "Sodédat 93"

Architect

Iwona Buczkowska, architecte D.E.S.A., Ivry-sur-Seine Design Team J.P. Conqui, I. Jeangeorge, T. Krupa, J. Furgalska, G. Rebboh

Structural Engineer Monsieur Uhalde

Timber Construction MARGET

Glulam Beams GAILLAUD

General Contractor SICRA

Date of Completion 1994

Costs

Total costs amounted to 50 million French Francs.

4 | Section through public gallery area before the corridor in classroom unit, scale i:ioo.

5 | View of entrance hall.

6 | Art room area. The balustrades are of steel since wood would be too massive.

5 | View of entrance hall.

6 | Art room area. The balustrades are of steel since wood would be too massive.

7 | Section through hall, courtyard and classroom unit, scale 1:500.

The irregular radial arrangement of the structural arches around the central courtyard results in building units that are neither too rigid nor too uniform. The collection of differently shaped spaces and rooms with their interesting views of the surroundings and the interior and the play of light and shade, all of it dominated by the ubiquitous arches, create an almost playful impression.

Structure | The many parabolic arches with their i6 m span and 9 m rise display a 140 x 600 mm cross-section and are of glued laminated wood. As Iwona Bucz-kowska points out, the same arches of steel would have to measure 400 x 600 mm. Wood is thus of much greater elegance. The distance between the arches is 5.90 metres; arranged parallel, they form the various building units. Between the arches 88 x 303 mm glulam beams with a spacing of some 2.80 m carry the weight of the roof. They support curved 65 x 132 mm glulam timbers, which, some 60 cm apart, form the horizontal roof construction. The outer surface of the roof consists of a shell of two 9 mm layers of plywood, under which are 10 mm gypsum plasterboards. In the spaces between the beams the plaster boards are covered with a 100-mm-thick insulating layer, and between the two is the vapour barrier.

The actual roofing consists partly of cedar wood shingles and partly - where the roof surface is not visible - of green roof sealing sheeting. As a result, the air space above the insulation is in each case differently designed. Where roof sealing sheeting is used, the gypsum plasterboard on the underneath is fixed to the beams by means of 28-mm-high metal rails, thus creating a 60 mm larger air space between insulation and top surface and ensuring effective ventilation. The roofing shingles are placed on wooden boarding running the whole length of the roof and connected to the plywood covering by 76-mm-high laths. In between is the sealing sheeting, thus creating an air space above the plywood layer to provide the necessary ventilation. There being no need for an air space under the top covering, the bottom gypsum plasterboard is in this case fixed directly to the beams. There are areas under the waterproof sheeting where the air space cannot be ventilated, either because they are too large or the number of windows too small - here the window connections allow for ventilation.

The fenestration is for the most part in the form of saw-tooth-shaped dormer windows that rise from the roof shells. Their roofs, also curved, spring from the main parabolic arches, which made their production easier. The load-bearing components in this case are curved 138 x 220 mm glulam beams which, with a spacing of just under 3 m (1/3 of 5.9 m), are fixed on one side to a main roof beam and on the other to the front of the dormer. Above these, 60 cm apart, are the 65 x 152 mm beams, also of glued laminated timber, which carry the same type of roofing as the main arches.

The entresol floors consist of two principal beams which span the spaces between the main arches and at two places are suspended from them. These ioo x 300 mm beams, also of glued laminated wood, are 150 mm apart. They are bolted at their ends to the main arches and, at two intermediate points, are fixed to the suspension struts. These are 30 x30 mm steel rods which, for aesthetic reasons, have been sheathed in wood. At a spacing of 5.9 m these principal beams carry the floor joists, on which the floor is laid, consisting of 19 mm chipboard, 20 mm footfall insulation and a second 19 mm chipboard layer as a base for the floor covering. Metal rails 18 mm high fixed underneath the floor joists carry 18-mm-thick gypsum plasterboards for the ceiling. The spaces between the joists are insulated with two ioo mm glass wool layers. Where the outside air is led in underneath, the heat insulation is attached to the floor surface above. In this way the air space is formed on the outside of the insulation, that is, underneath it.

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