Old Shed New House, Great Ouseburn, North Yorkshire

Introduction

What was once a run-down shed, a container for tools and tractors, has been transformed by architect Tonkin Liu into a new house, now a container for a lifetime collection of books and art. In its basic shape and cladding, the house echoes the original shed. The original steel portal frame has been reused and extended, infilled with a new timber frame and, like the original shed, clad with timber boards. The new house is energy-efficient and built to a tight budget, with a quality of design for which it has won many awards.

The client, the parents of Greg Storrar, project architect at Tonkin Liu, wanted to build a house in a quiet rural area where they could spend their retirement. They found the site, which once formed the rear part of a large garden, in the small village of Great Ouseburn (between York and Harrogate). Road access is from the rear of the site, where a track lined with birch trees leads the way to the house, which looks out to mature trees, an ancient pond, and views of farmland. The orientation of the old shed has been retained, with the main entrance facing east and the wide gable wall facing south.

As well as the usual living spaces - living room, kitchen/dining, bedrooms - the client had two particular requirements; a space to exhibit their collection of art, and a large library to store their book collection. The art has been accommodated in a long, double height gallery which runs right through the building from the main entrance at the east, where it aligns with the entrance approach, to the kitchen/dining room on the west. The books are housed in a library, also a doubleheight space, set at the centre of the southfacing gable wall, with the open plan living room and an accessible en-suite bedroom at either side. The library walls are lined with mirror-backed book-shelves which rise to the roof, while the south wall is glazed, with sunlight modulated by an external canopy. On the first floor are two more en-suite bedrooms, linked by a lightweight bridge which spans over the library and leads to the staircase. This staircase, together with utility room and storage spaces, are concealed behind a thick wall running along the north side of the long gallery. The result is a set of interconnected spaces, some small, some double-height, which create a sense of volume and light in a compact plan.

The use of timber

Traditional construction techniques and lowcost materials were used to ensure that the modest budget could be met. The joinery throughout the internal spaces is of Latvian birch plywood finished with Osmo PolyX oil in white. The external timber cladding takes an innovative approach to traditional techniques. It consists of bands of horizontal boards, reflecting the original cladding of the old shed, set between a series of vertical galvanised steel fins. The boards are Siberian larch, rough sawn, shot-blasted to enhance the grain, and finished with Woca silver exterior wood oil. The boards vary in size and are lapped between the vertical steel fins, forming bays which vary in width. This creates a rhythmic façade, an oblique reference to the variegated bark of the silver birch trees that surround the house. At the eaves, fins and cladding terminate in a galvanised steel capping plate with a concealed gutter behind.

The fins also act as window and external door reveals and extend above the large glazed panels to form canopies, supporting larch louvre sunscreens. At each corner of the building the end fins of adjacent elevations are welded together on their inside edges, forming an angle which is welded at roof level to the capping plate. This detail disguises the bulk of the external wall by revealing only the fin, which is just 8 mm thick. The lowest levels of larch cladding terminate above ground level to protect them from the weather. The exposed wall below the larch is lined with a galvanised steel plate which acts as an end stop to the steel fins. It runs just above shingle-filled perimeter drain and forms an external skirting to the building.

The structure

Mervyn Rodrigues, structural engineer and Director at Rodrigues Associates, describes the structure:

‘The original three bay steel portal frame of the agricultural shed is extended longitudinally and vertically, and laterally by increasing the spacing between frames. The existing steel portal frames were dismantled, and new sections inserted to achieve the increases in length and height.

'Internal columns, two per frame, were installed to reduce additional forces and moments imposed by both the increase in size and the additional weight from the new green roof and supporting timber roof structure.

'Timber framing in the perimeter walls together with plywood sheathing provides longitudinal and lateral stability to the building, and timber purlins/joists and plywood decking provide plate stiffness to the roof, allowing the traditional diagonal bracing in the walls and roof, normally associated with agricultural buildings to be removed, increasing the thermal efficiency of the building by reducing thermal bridging.

'Shallow depth stressed skin floors minimize floor construction and maximize floor to ceiling height in the rooms on the ground floor and the first floor.

'Galvanized steel fins secured to the timber framing serve as an exoskeleton to both carry the timber louvres that wrap the building and to provide support to the two cantilevering canopies. The canopies serve as a porch to the main entrance and a shading device to the large south-facing glazed façade of the library. The steel fins are braced by the timber louvres to ensure that the plate thickness could be kept to an absolute minimum, varying from just 8mm to 15mm.

Internally, galvanized steel structural steelwork is also used to support a lightweight linking bridge and library mezzanine floor. The fabricated steel sections used in the bridge and mezzanine are of minimum size and were carefully detailed to reduce their visual impact and to match the appearance of the external steelwork.‘

Sustainability

FSC and PEFC certified timber is used throughout the project, selected for its sustainable properties to reduce the carbon footprint of the building. The frame is spruce, Siberian larch is used for the external cladding and the solar louvres, and BB grade Latvian birch plywood is used for the internal joinery.

The building envelope is highly insulated and air tight and, following passivhaus principles, is complemented by mechanical ventilation with heat recovery.

The large fixed glazed elements are balanced by smaller triple-glazed openings to achieve a 0.25 window to wall ratio.

The building is heated with a high efficiency gas boiler with underfloor heating on the ground floor and planar radiators on the first floor. Renewable energy sources comprise flat plate solar thermal for hot water provision and solar photovoltaics for electricity generation. The building is ventilated mechanically with heat recovery in the cooler months and passively via openable windows and skylights in the warmer months.

The design was reviewed by Integration, the services engineer, against the impacts of future climate change, specifically in relation to summertime overheating, which is a growing concern with residential buildings. Their analysis showed that the risk of overheating was not significant.

The green roof improves the biodiversity of the site and attenuates storm water so that it can all be discharged directly to the existing pond. Low flow fittings are installed throughout the building to limit water consumption.

Annual predicted carbon emissions are 11.39 KgCO2/m2/yr.

Awards

Winner, Wood Awards, 2018
Winner, Stephen Lawrence Prize, 2018
Winner, RIBA National Award, 2018
Winner, RIBA Yorkshire Award, 2018
Winner, RIBA Yorkshire Small Project of the Year, 2018
Winner, AJ Retrofit Award, 2018
Overall Winner, GaGA Awards 2018
Finalist RIBA House of the Year 2018
Finalist, RIBA House of the Year, 2018
Finalist, AJ House of the Year, 2018

Completion Date:

November 2017

Building Type:

Private house

Location:

Great Ouseburn, North Yorkshire

Architect:

Tonkin Liu

Structural Engineer:

Rodrigues Associates

M & E Consultant:

Integration

Main Contractor:

Vine House Construction

Joinery:

Image Developments Northern Ltd

Timber Supplier:

Arnold Laver, Leeds

Timber Elements:

Cladding, frame, internal joinery

Timber Species:

Siberian larch, Latvian birch plywood, Scandinavian spruce

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