Nielsen Housing Estate Boras

Tegnestuen Vandkunsten

Subject | Boras is a small Swedish town about 50 km east of Goteborg. In 1990 the town's Urban Planning Director Hasse Johansson initiated a competition for a "Nordic Building Exhibition". Houses designed by Danish, Finnish, Norwegian and Swedish architects were to be erected by 1994 in the garden town of Hestra on the northern edge of Boras. The aim of the competition was to instil new momentum into the good but formally rigid style of Swedish housing design. The prizewinners should incorporate their ideas for and their experiences with social housing in their own countries and build examples of this among the trees, fields and rocks of the site chosen for the competition. The architectural team of Tegnestuen Vandkunsten from Copenhagen in Denmark was chosen, a group which had already attracted attention with a number of interesting housing projects. At first, the Swedish contractual system, which separates the planning side (architect) from the construction side (contractor), conflicted with the Danish system, in which drawing up tenders and on-site supervision are part of the architect's remit. However, the possible difficulties were eliminated through a personal agreement. Jens Thomas Arnfred, the responsible project architect and co-founder of Vandkunsten, was very familiar with the Swedish planning and building system as a result of his teaching experience at the Chalmers University in Goteborg. Furthermore, the boss of the building contractor Fristad Bygg visited the architect's offices in Copenhagen in order to find out about the Danish system of building. In the end, this led to optimum cooperation; the architect was able to take part in the decision-making concerning constructional details while work was proceeding on site. This is normally impossible with the contractor system but in this case it proved its worth in every sense.

Location

"Nielsen" Housing Estate, Hestra Parkstad Symfoniga-tan, Boras, Sweden

Client

AB Bostader, Boras Architect

Tegnestuen Vandkunsten, Copenhagen, Denmark

Structural Engineer STIBA, Sven-Olof Augustsson

General Contractor Fristad Bygg, Fristad, Sweden

Date of Completion 1994

Costs

The cost for a total living space of 3596 m2 was 45 million Swedisch Kronor, including all ancillary construction costs. This equates to a price/m2 of 12 500 Skr.

Design | It was an attractive elevated rural site with two knolls. The architect placed ten slim, extended rows of houses fanning out around the two knolls, thus achieving optimum landscaping across the whole site. At the same time, the topography of the site was emphasized by the buildings being laid out in the same direction as the slope of the ground. The buildings are up to three storeys high, growing out of the slope under the horizontal line of the eaves.

The individual buildings comprise three to five terraced houses differing in height. The road around the site passes through an opening in each of the buildings. This is situated between the uppermost single-storey house and the other houses, and extends up to the underside of the roof.

6 | Vertical section, scale i:25-1 Metal capping.

2 Spacer piece and protection against drifting snow.

3 Fibre-reinforced cement board, 6 mm. 4 Glulam ridge purlin, 140 x 495 mm. 5 Glulam eaves beam, 140 x 270 mm. 6 Roof construction: 2 layers roofing felt, 23 mm boarding, 45 mm air gap, 220 mm thermal insulation between rafters (45 x 220 mm + 45 x 45 mm), vapour barrier, 28 x 70 mm battens, 13 mm plasterboard. 7 Wall construction: profiled fibre-reinforced cement cladding, 38 x 70 mm pressure-impregnated battens, airtight sheeting, 120 + 45 mm thermal insulation between 45 x 120 mm timber members and 45 x 45 mm battens, vapour barrier, 13 mm plasterboard. 8 Floor construction: Beech-wood flooring, one layer 500 g bituminous felt,

22 mm chipboard, 70 mm insulation between 45 x 195 joists, sheeting, 22 x 70 mm battens, 13 mm plasterboard.

l\ Horizontal section through wall, scale 1:25, showing the loadbearing 95 x 95 171171 members and the 45 x 120 mm members in the thermally insulated infill panels and the connection to a loadbearing wall.

During the planning, special attention was paid to creating diverse types of rooms. Likewise, providing a view of the attractive rural surroundings was also taken into account. Following this principle, the two- and three-storey terraced houses each have a two-storey void linking the kitchen below with the living room above. This created an exciting interior and interesting natural lighting effects.

Large overhanging eaves and the continuous narrow row of windows just below emphasize the slim nature of the buildings. The light-colour natural wood window frames contrast very effectively with the black, profiled fibre-reinforced cement wall cladding. The carefully detailed design illustrates the philosophy of the architects: to use simple and cheap building materials as far as possible but to demand the best craftsmanship and best materials at those places where people come into contact with the structure. This is a philosophy also adopted by Ralph Erskine. Therefore, the simple but stable construction with its industrial-type cladding allowed funds to be redirected into providing generous interior layouts and creating differences between the individual houses. This enabled the budget to be kept within the mandatory cost framework for social housing in Sweden.

Structure | It is a timber stud system consisting of 95 x 95 mm members which are continuous from concrete foundation to roof, i.e. a maximum of three full-height storeys. In the meantime, in Sweden as in other countries, timber houses having more than just two storeys are also approved by local authorities. The buildings are braced by the transverse party walls between the houses as well as by the other structural internal walls, all of which consist of 13 mm plasterboard on both sides of 45 x 95 mm members with 95 x 95 mm members at the ends. The ridge purlins and eaves beams are the only glulam members in the entire construction and are supported on the party walls. The eaves purlins are 140 x 270 mm and the ridge purlins 140 x 495 mm. The 45 x 195 mm joists of the intermediate floors are also supported on the transverse walls, i.e. parallel with the longitudinal sides of the building. Although the width of the building is only 6 m, to span the joists in this direction is not unusual in Denmark and Sweden. This technique allows the external walls to remain as non-loadbearing, uninterrupted, independent infill panels inserted between the loadbearing timber columns.

The external walls comprise 120 x 45 mm members with 120-mm-thick thermal insulation in the bays, 45 x 45 mm battens fixed in front transversely with 45 mm thermal insulation in between. This eliminates any through-joints in the insulation which has a total thickness of 120 + 45 = 165 mm. On the inside there is the vapour barrier and 13 mm plasterboard. The external insulation is covered by an airtight lining underneath the external cladding which consists of black, profiled fibre-reinforced cement sheeting fixed horizontally on pressure-impregnated 38 x 70 mm battens.

The ridge purlins and eaves beams carry 45 x 220 mm timber rafters at 800 mm centres. Between the rafters is a 220-mm-thick thermal insulation with the vapour barrier underneath. The ceiling is 13 mm plasterboard on 28 x 70 mm battens. A 45 mm air gap is formed above the insulation by means of 45 x 45 mm battens which are nailed along the top of the rafters. Fixed to these is the 23 mm tongue-and-groove boarding and the whole roof is covered with two layers of roofing felt. The rafters extend 1.20 m beyond the eaves beam; here, the 45 x 45 mm battens are fixed across the rafters. The roof construction consists of a 6 mm fibre-reinforced cement board, the 23 mm tongue-and-groove boarding, the roofing felt and the gutter along the edge. At the gable ends the overhang is formed by the projecting ridge purlin and eaves beams. Interesting and effective is the detail at the ridge where the ridge purlin projects above the line of the roof and the air gap above the insulation is ventilated at the sides of the purlin.

The intermediate floors comprise loadbearing 45 x 195 mm joists at 400 mm centres. Insulation, 70 mm thick, is placed between these and finished off with sheeting on the underside. Like the roof, the ceiling is 13 mm plasterboard but here carried on 22 x 70 mm battens. The floor construction consists of 22 mm chipboard nailed to the joists followed by a layer of 500 g bituminous felt to which beechwood strip flooring is glued. Despite the low impact-sound insulation, this type of construction is acceptable in Sweden when the floor is between rooms within the same occupancy.

All timber elements are joined to each other by means of nailing plates or metal fixings.

8 I Elevation showing horizontal profiled fibre-re-inforced cement cladding and untreated wood windows. The supporting structure for the elevated entrance walkway is made from hot-dip galvanized steel.
Homeowners Guide To Landscaping

Homeowners Guide To Landscaping

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