Pierre Smard Residential Development Le Blanc Mesnil

Iwona Buczkowska

Subject | Residential developments, especially when they are built using standardized components to keep costs down, can easily turn out drab and monotonous. Nevertheless, it is the task of the planners to make such developments lively and interesting. Using standard terrace house designs, however, urban developments rely mostly on the nature of the sites available and very little on the houses themselves. New forms, aimed at achieving greater integration and the formation of clusters, have evolved from the hitherto conventional developments with detached and terraced houses. This trend was helped, perhaps even instigated, by the relaxing of rigid building regulations, in particular by the introduction of mixed vehicular/pedestrian traffic areas. In the forefront here were planners in the Netherlands who as early as the late seventies permitted so-called "Wohnerf-ten", i.e. streets in which pedestrians and vehicles share equal priority. Standardized buildings could thus be grouped into a development with a coherent but varied form. The Dutch provided some early and astounding examples of this type of settlement (Alkmaar, Zoetermeer).

Local authority requirements regarding fire protection have also become somewhat better differentiated, thereby allowing the approval of concentrated timber-frame developments provided that certain conditions are satisfied. This change in attitude has led to developments like the one described here - 225 housing units on the north-eastern outskirts of Paris; an interesting housing estate formed from an agglomeration of identical buildings - and all built entirely from timber.

Design | The architect Iwona Buczkowska was given the task of creating a densely-settled housing estate. The site was adjacent a railway line near a station in an existing residential area consisting of detached houses. Despite the density of the development it should reflect and augment the scale and intimacy of the surroundings. The aim of the architect was to redefine the traditional urban vocabulary of streets, squares, passages, etc. in a modern way, to create an organic diversity of angular passageways, internal courtyards, semi-private and private zones. The fluid relationship between the buildings and their surrounding or

Location

Rue Pierre Sémard, 93150 Le Blanc-Mesnil, France. The estate is situated adjacent "Le Blanc-Mesnil" railway station on the Paris-Roissy Airport route.

Client

Sodédat 93 (Société départementale d'aménagement du territoire de la Seine Saint-Denis) appointed by Le Blanc-Mesnil council.

Architect

Iwona Buczkowska, Ivry-sur-Seine

Structural Engineer Ing. Truong (prototype); the contractors were responsible for subsequent phases.

Timber Construction CM BP (prototype), Houot (1st phase), Ouellec (2nd phase)

Date of Completion 1992

Costs

The average cost was 5000 French Francs per m2 of usable floor space.

4 | Plan of typical floor construction, scale i:200. The uniform loadings on the main beams in both directions are achieved by the diagonal arrangement of the floor joists. The various column/beam connections at the intersections of the grid lines are drawn at a scale of 1:50.

5 | Joint between main beam and column, scale i:io. In the prototype and the 1st phase the columns are connected between floors by a 90 x 90 x 390-mm-long hollow section to which the incoming beams are attached. Welded onto this hollow section top and bottom are square end plates with connecting lugs containing nailing holes for fixing the beams and columns.

enclosing spaces should create a lively experience and be an ever-present aid to orientation. A simple basic module arranged in a variety of combinations would create this vivacity but, at the same time, instil a sense of coherence. The architect decided on a basic unit measuring 4.90 x 4.90 m. Up to a height of three storeys these units would have a double monopitch roof with the common low point on the diagonals. The outcome of this design is that, externally, dynamic roof peaks ensue which determine the enduring appearance of the development. The project was carried out in several phases. A prototype consisting of five housing units was built in 1986 to illustrate the possible combinations, overall appearance and technical details. The first phase comprising 88 housing units was completed in 1988, and the second phase followed in 1992 with a further 132 units and 700 m2 of floor space for commercial purposes. The final phase of 50 units, a kindergarten and other communal facilities has not yet been built.

6 | Section, scale 1:600. Basement garages and commercial premises are constructed in reinforced concrete.

Structure | The entire estate is built using timber-frame construction. Reinforced concrete is only used for the basement garages and commercial premises, which form the foundations for the timber-frame housing above.

The whole scheme is based on the constant 4.90 x 4.90 m grid. Positioned on the grid intersections in the prototype and the first phase are loadbearing 160 x 160 mm glulam main columns, each just one storey high. In the second phase the columns are 140 x 140 mm and are continuous over the full height of the building. The main floor beams - on the grid lines, i.e. 4.90 m long - are 380 x loo mm glulam members fixed to the main columns. These main beams carry the actual 250 x 50 mm floor joists arranged at approx. 600 mm centres and at an angle of 450 to the main beams. This means that all main beams in both directions are equally loaded. Apart from that, this diagonal arrangement matches the geometry of the entire development, which is comprised of the squares formed by the grid itself and by halving these squares diagonally.

The roof surfaces give the whole settlement its very own identity; the roofs rise in monopitch form from the diagonals and so sharp peaks ensue at the corners of the squares. The roof pitch is the result of the geometric relationship of the ridge being exactly one storey above the eaves. The roof support beam - a 380 x 95 mm glulam member - is positioned on the diagonal unless there is an internal wall underneath; in this case the support is formed by two 496 x 44 mm beams, one on each side. The 150 x 70 mm rafters at 1.36 m centres rise from these roof support beams to carry the 120-mm-thick sandwich-construction roof deck. These sandwich elements are 450 mm wide and consist of chipboard outer layers with a 100 mm thermal insulation filling. The waterproofing is provided by roofing felt with a bonded white gravel topping.

In the facades the main columns are replaced by the facade construction which, for structural reasons, is offset outwards from the grid. The timber-frame façades are made up of 115 x 115 mm columns on the grid lines and intermediate 115 x 38 mm vertical studs at a spacing of 600 mm which are connected to con-

6 | Section, scale 1:600. Basement garages and commercial premises are constructed in reinforced concrete.

7 | View of an apartment storey showing exposed diagonal roof beam and ceiling rising on both sides.

8 | Façade construction, scale i:io. Illustrated here are an external corner and the junction with a separating wall. Façade construction from outside to inside: vertical i8 mm lapped larch weatherboarding, 25 x 50 mm counterbattens, protective sheeting, 9 mm plywood, 120 mm thermal insulation in the bays of the timber frame (115 x 115 mm columns, 115 x 38 mm intermediate studs), vapour barrier, 15 mm metal rails,

13 mm plasterboard.

9 | Roof construction, scale i:io. The 380 x 95 mm diagonal roof beams support the 150 x 70 mm rafters which in turn carry the 120 mm sandwich decking (with 100 mm thermal insulation) and the waterproofing on top.

to, right | Vertical section, scale 1:20. Top: junction of roof with twin-leaf diagonal separating wall. Centre: junction of floor with external wall; the timber-frame facade connects to the main beam above and below; the inside face of the beam is provided with 40 mm insulation. Bottom: junction between base of timber façade and concrete substructure (foundation or commercial premises).

11 I Joint between internal partition and main column, scale i:io. The separating wall has two leaves. One leaf consists of 95 x 40 mm timber framing with io mm plywood and 13 mm plasterboard on the room side and 100 mm insulation in the bays. The other leaf, spaced 25 mm clear of the first leaf, is formed by a framework of 40 mm steel sections onto which 13 mm plasterboard is fixed. Polyurethane foam is used to seal the joints with the columns.

tinuous 115 x 7° 171111 wall plates top arid bottom. Glassfibre insulation batts, 120 mm thick, are placed in the bays and then covered on the interior face by a vapour barrier. On the outside the frame is covered by an airtight layer of 9 mm plywood and a protective breather paper. The weatherproofing is formed by vertical 18 mm lapped larch weatherboarding fixed to 25 x 50 mm counterbat-tens.The internal walls are finished with 13 mm plasterboard on 15 mm metal rails.

Internal partitions are in timber-stud construction like the external walls but here consist of 95 x 36 mm battens'with 13 mm plasterboard to both sides. The separating walls between apartments are constructed in two leaves, one of which comprises 95 mm timber framing with 10 mm plywood and 13 mm plasterboard on the room side, with 100 mm insulation batts placed in the bays. The other leaf is simply a 40 mm metal frame onto which plasterboard is fixed. There is a gap of 25 mm between the two leaves. Polyurethane foam or additional insulation batts are provided at joints to prevent sound transmission.

The intermediate floors consist of the 250 x 50 mm joists already described onto which 65 x 38 mm battens are fixed in order to carry the 25 mm chipboard flooring. The ceilings are formed by two layers of 13 mm plasterboard fastened to an acoustically insulated metal frame. Insulation, 100 + 60 mm, is placed between the joists.

12 | View along a main access corridor.

13 | Looking from the 2nd floor onto a main access gallery.

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