London Terrace House
Architectural design
This originally 19C house was on 3 floors and had been divided into 2 flats. There was little connection with the garden which was occupied by a bomb shelter construction. The intention was to remodel and extend the house to make a large family home configured by living spaces which optimised their connection with their setting through views, introduction of daylight and the use of natural materials. At the upper levels large areas of glazing give views of the surrounding urban context and the rapidly changing face of Shepherds Bush.
This reinforcement of connection with the setting was made possible by organising all the services rooms in the centre of the house and freeing up living spaces at the back of the house to connect directly with the outside. Bathrooms are stacked vertically on 2 floors on top of the ground floor kitchen. Small service rooms to the original house, which had been accessed off the stair half landing, were demolished to allow main floor levels to be matched and extended through to the rear of the house. With higher ceiling levels the interior of the house became opened up to the rear, allowing new expanded views and better natural light.
A slender double height top lit atrium provides important daylight and views from the stair and lower rooms. The fish pond at the base of the atrium and a trellis with climbing plants extend the garden theme into this space. Simple steel and glass details against the concrete frame create an elemental space.
In contrast to the neighbouring houses with larger garden plots which could accommodate single floor kitchen extensions the garden at no 8 was small being curtailed by a small conservatory building, part of the neighbouring property. The solution was to make one continuous space between inside and out with fully opening doors so that the whole extended ground floor area could be used either as a garden or as a semi enclosed dining/kitchen area.
By cantilevering the new upper floors out over the ground floor a dynamic relationship is expressed between inside and out in which the garden extends inside to the ground floor areas under the cantilever whilst the upper floors project out with wide open views of trees, sky and changing city panorama beyond.
Each of the new living spaces at the rear of the house has a special interpretation of the garden idea:
At ground level the slender economic concrete frame structure blurs the distinction between inside and out supporting a fully glazed enclosure with maximum transparency. Tall oak framed glazed doors are hung from the concrete and can be folded back to make a continuous open space between kitchen, dining area and garden. The fair-face concrete finish extends a language of external garden materials into the house. A narrow fish pond slides under the double height glazing into the tall atrium so that fish swim freely between inside and out.
At first floor level a new studio space is lit by the cool north light of the atrium skylight. A large garden window makes the connection with garden trees and climbers. A freshwater aquarium embedded in the internal wall re-introduces the aquatic theme of the fishpond and allows a subtle visual connection with the internal bathroom while maintaining privacy.
At second floor level the new bedroom is visually connected with the garden terrace above by a narrow roof light. A large horizontal corner window gives city views of the tube line and BBC to the north and east.
The top floor penthouse flat is fully glazed on the east side with access to a roof garden. Changing panoramic views of the White City shopping centre under construction can be seen over the top of the tube station. A ladder leads to the upper green roof which is planted in sedum and succulents.
Project management
This house is owned by architect Iona Foster and husband Dominic Parkinson. From the beginning we decided to retain control over the management of the work and carry out ourselves as much of the work as possible. Concrete work, brickwork and the supply of timber windows were contracted by specialists but nearly all other work was carried out on site with the help of casual labour. We lived in the house during the whole period of construction fitting a programme and sequence around our specific needs and availability of our time.
Planning approval
The initial proposals for the extension were using a ‘bio’ cladding which was to be light system of polycarbonate panels supporting climbing plants. The cantilever was to be structurally supported using steels. When this was tested in a consultation with Hammersmith and Fulham planners we were advised that though there was no objection in principle to the proposed extension it would only be accepted if clad in facing brick to match the existing. This prompted a rethink of the structural strategy for the cantilever to find a solution which was consistent with the language of the brickwork cladding and its implied weight. A concrete frame with ‘piloti’ at ground level would provide the structural strength and the right material quality.
Structure
Structural design was by Martin Waters of Haskins Robinson Waters www.ehrw.co.uk
Concrete frame
The use of an in situ concrete structure for a small domestic extension is unusual. Concrete work is well suited to larger projects where there are economies of scale and where the potential strength of concrete is exploited for large or difficult spans. In this case the qualities of the concrete were used to manage the cantilever supporting brickwork and upper floor structure, the awkward party wall requirements and to create a slim and elegant structure at ground level which would be visible, not requiring finishes and would extend the language of the exterior garden into the ground floor. The below ground concrete work was substantial and the footings provided excellent foundations for the structure. The completion of foundations and above ground structure within one trade was an advantage in coordination and sequencing.
The small volume of concrete work and the interface with existing building structure required particular attention to the accuracy of formwork and each specific detail. Every aspect of the concrete was custom made and unlike most in situ concrete work there was little repetition of details or formwork layout.
Whilst the shape and details of the concrete were specific to this project the intention with the concrete itself was to use standard materials and formwork for a consistent and an ordinary, appearance to the concrete surface. A standard OPC concrete mix was specified with selected sand for its relatively light colour. Avoiding the use of colour or white cement was recommended to ensure consistency in colour. The shuttering system was the faced plywood ‘Pourform’ which gave a consistent fine smooth finish.
Concrete contractor Whelan and Grant agreed to price and contract the work though they admitted this was a departure from their usual portfolio. The successful delivery of the concrete relied heavily on their expertise and in particular the carpenting skills of the foreman ‘one mil Paul’ whose accuracy and attention to detail had earnt him the title and a reputation that preceded him.
Temporary works
The challenge with the new concrete structure was to stitch in the concrete under the existing brickwork and temporarily support the rear elevation of the house and the load of the roof structure whilst doing this. A system of ‘strong boys’ and ‘needles’ was used by our in house engineering team.
Windows and glazing
Windows in the new brickwork are in American white oak, natural finish. The garden doors at ground level, also in American white oak, are bi-folding and when open allow a clear 3 metre high opening the full span of the concrete, creating a single space of garden with interior dining area. All timber windows and doors were supplied by Wedd Joinery.
The glazed atrium over the fishpond has single glazing framed in simple steel frame and supported below the pond water level. The rooflight is double glazed.
Stairs
To meet the new floor levels of the extension the stair connecting first and second floors was stripped out and replaced with a new more compact stair with winders at top and bottom.
The steel stair at first floor landing was fabricated from 10mm sheet mild steel laser cut and welded by local welder John Avakian.
Penthouse flat
The roof to the rear (east side) of the main house, originally pitched, was raised to form a new flat roof which encloses the top floor penthouse. The new glazing is designed to give maximum transparency to enjoy the far reaching views at this level. A single steel spans the full width and infill glazing is framed in steel with aluminium sliding opening doors.
Roofs
New green roofs to the extension and to the top floor penthouse flat were well insulated, finished in GRP and planted with sedum, succulents and grasses.
Kitchen
Stainless steel worktop was supplied by Roundhouse Kitchens.
Garden /external works
The garden has been completely rebuilt with all new plants and landscaping. An existing air raid shelter in the middle of the garden was demolished. The paving level was raised to match the indoor floor level and a raised deck constructed in cedar boards with garden storage area underneath. The fishpond provides a buffered rainwater reservoir storing water from the glazed atrium roof with a low energy gravel filter.
The giant ‘hamster wheel’ exercises a very energetic collie dog and is made using a lane divider bobbin recycled from the local swimming pool.