The incredible, moving bungalow extension

Crawford Partnership's RIBA competition winning scheme to extend a stock of up 3,000 bungalows in the Doncaster area switches the front and rear access and attaches a partially prefabricated module to the new front. The extra 'garden rooms' created by the modules let in light, create private courtyards and add extra sapce to the house which make them suitable for wider range of residents.

Currently these bungalows offer limited accommodation with the kitchens and bathrooms being particularly small and are increasingly failing to meet the aspirations of customers so a competition was launched on behalf of St Leger Homes, the Arms Length Management Organisationwhich manages the houses on behalf of Donaster council, to alter and extend these bungalows.

The client’s brief highlighted the need to reverse the decline of the area and turn it into a sustainable community which will thrive in the future. New and improved homes to meet the existing and future housing needs of the local community are imperative in achieving this goal.

The design solution would need to be inherently flexible to meet the needs of a diverse range of occupants, be economic to construct, act as a catalyst in creating a greater sense of identity and place, and be constructed from sustainable materials.

The ‘plug-in’ extension

It quickly became apparent that any proposal to introduce a second room or bedroom would involve building a new extension onto either the front or back of the existing bungalow. It was decided that the new extension should be positioned on the carriageway side of bungalows as this is, in general, where the larger areas of garden tend to be located and the area will provide adequate space to introduce the new plug–in ‘garden room’ extension.

Although visually connected to the main house, the new garden room is designed as a stand alone ‘plug on’ extension to the main bungalow and provides a second bedroom/study/home office space of 12.7m2.

The garden room is linked to the main house by a connecting lobby of 2.8 m2 that incorporates an internal open glazed lightwell enabling sunlight and daylight to penetrate into both the existing house and the new extension and maintaining continued ventilation and light for the bathroom of the main house. This lobby also gives access out to the parking area from a secure entrance door.

The garden room is constructed utilising a timber framed flat pack ‘kit of parts’ that can be added to as desired with optional component spaces such as the 2.5 m2 bin/bicycle storage module. The extension is proposed to be completely autonomous whilst at the same time fully integrating with the main house. The suggested new interior layout provides a modern, bright and comfortable space that can accommodate a range of interior layout configurations to suit adults (double bed and workspace), children (twin single beds or bunks) and the elderly and infirm (mobility standards).

The new garden room extension and other elements are combined to provide private, secure and contemplative areas both internally and externally

Creating courtyards

The garden room unit is designed to located in a variety of positions across the back of the existing bungalow by minor adaptation of the linking lightwell feature. For our current submission we proposed a street layout that attaches the garden rooms in an alternating pattern of solid extension and open garden space, effectively creating a series of private garden courtyard areas within each plot and designed as a planted ‘living wall’ meshed screen as amenity for neighbouring plots. The units can also work in a back to back mirrored configuration.

The new garden room extension and other elements are combined to provide private, secure and contemplative areas both internally and externally. It is likely that prospective future occupants may be car owners and we have incorporated hard standing as part of the integrated garden design.

The garden room kit of parts proposes a bin/bicycle storage module and also incorporates a planter tub module in galvanized steel, within which we would propose to plant medium sized trees. The existing bland landscape could be economically and simply enhanced by the introduction of just one tree per garden providing colour and visual interest. A landscape designer has suggested that trees such as Prunus Autumnalis (Winter Flowering Cherry), Acer Davidii Griseum (Paper Bark Maple) or Betula Jacquemontii (Silver Birch) would grow well in this location.

On the front of the existing dwellings, minor alterations to the façade to provide new glazed patio doors and a reworked ‘porch’. Again, this has been considered in the context of access to the gardens and we believe that by introducing a more transparent connection to the outside of individual dwellings combined with simple methods of enclosure, gardens could become a significant amenity for residents providing vibrancy, colour and individuality in the streetscape, and with associated health benefits that are difficult to quantify in monetary terms.

Green credentials

The entire design seeks to incorporate sustainable and energy saving products and methods of construction. The extension would be constructed utilising timber framed ‘off site’ prefabricated construction for walls, floor and roof and delivered as a ‘flat pack’ to site ready for immediate installation. The proposed foundation supports of lightweight steel piles take about two to three hours to install and do not require the “dig and dump” of traditional foundations. Individual extensions could be substantially completed within 10 to 14 days, with minimal disruption to occupants and neighbours

Specification

The timber structure meets modern house building standards. The multi layered construction provides a wall thickness of 200mm which is fully insulated with high performance ‘Warmcel 100’ natural cellulose fibre loose fill insulation including vapour control and membrane. Ventilated layers prevent the timbers from decay. The western red cedar cladding is naturally resistant to moisture, decay and insect damage. It is a sustainable timber from certified managed forests with a high durability as it lasts up to 40 years untreated and has high dimensional stability.

The flat and pitched roof areas of the garden room are finished with ultra-low maintenance organic ‘sedum’ plants which reduce visual impact, absorb rainwater reducing the impact of run off on the storm water drainage system and the likelihood of local flooding, provide biodiversity of wildlife, provide cooling in summer and improved insulation in winter.

Internal walls are made from premium-grade birch plywood while the double glazed pivot windows incorporate Pilkington’s ‘Low E’ glass and argon filled cavity with high-performance, Scandinavian pine frames using inbuilt trickle ventilation. The extensions have underfloor heating.