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How did changes in permitted development rights influence this house by Cassion Castle?

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At Oak Lane House Cassion Castle has taken advantage of planning changes to create a Californian house with Fenland characteristics, says Tim Abrahams

PLANS • SECTION • DETAILSPROJECT DATA • SPECIFICATION 

Things are moving in the country. Not massively; not in any orchestrated way, and certainly not on the scale they need to, but they are moving. The alterations in permitted development rights for the change of use of agricultural buildings made in 2013 and 2014, designed to spur on recalcitrant planning authorities into updating their local plans, may not have achieved that goal, but in some areas it has changed the emphasis in favour of development. With local authorities understanding their control can be partially circumvented, the log-jam of permissions is freeing up a little. As a result, a culture change is occurring, albeit inhibited by administrative resistance as much as a lack of resources.

Oak Lane House in rural Suffolk is a result of what might be achieved in this new condition in a part of the country that has been more positive about the change in planning than the more truculent areas. (Cornwall is frequently referred to as the area of greatest resistance.)

Although the design of this impressive, two-storey house in flint and timber benefited from an earlier change in permitted development (the confused 2008 Town and Country Act), whereby development within the curtilage of a rural dwelling house could be extended in certain ways, it is a positive sign of what is possible in these slowly changing circumstances.

Architect Cassion Castle has benefited from the change in culture. When he approached the St Edmundsbury planning authority they agreed that the existing property on Oak Lane could be replaced. However, they also kindly pointed out that he, acting on behalf of his brother client, was permitted to first conceive the property as it might be extended under permitted development – in this case by an extrusion of the front façade to within 2m of the curtilage boundary – before calculating the volume of the replacement property. From an existing volume of 268m3 they were allowed to scale up to 1,948m3.

Castle’s design has more in common with American Modernists than more recent Postmodernist precedents

In the end they didn’t require as much, using 1,880m3, including balconies on the first floor. The massively increased floor surface area has been put to good use, providing a new, six-bedroom house for the architect’s brother and his family, inhabiting the 6-acre plot in a stimulating and thoughtful fashion, rather than filling it. The rectilinear villa, designed around a pinwheel plan, presents a bold frontage on the approach from the north-west, but to the south unfolds into the landscaped setting. Castle’s design, despite the materials, has more in common with the laid-back American Modernists than the uptight, self-referential versions of more recent Postmodernist precedents.

The house is firstly legible as a double layer of volumes. The ground-floor façade is clad in hand-laid knapped flints, laid over 100mm-thick, medium-density blockwork walls. The first floor façade is clad in 144mm strips of European Larch, painted black. This isn’t simply a desire to seem contextual and to fit in, because it cannot be seen from the road nor from any other development. Of course, the use of the two different tones visually disaggregates the solid block of the building, but there is more to it. The robust materials are in many ways a statement of intent about rural living: a commitment to the messy stuff of a place.

On closer examination these two layers have been broken down into smaller volumes and in places pulled out of direct alignment. Indeed the experience of the house, particularly on the ground floor, is not volumetric, but rather of a generous, thoughtful plan. Castle has shown an admirable dedication to the logic of a central communal space with specialist functions spinning off from it that one might see in a Neutra or Lloyd Wright house. One enters the house from a north-facing entrance into an utterly central space. To the north a roof light, created by a tiny recess in the upper floor, helps define the long wall. The frame is steel, so these offsets can be done minimally and without great theatre and expense.

Its grand gestures are about dissolving partitions rather than making them grand

Not that the house isn’t without its grand gestures. They are, however, about dissolving partitions, rather than making them grand. As one passes towards the kitchen, the glazing on the southern side of the sitting room and on the eastern side of the kitchen can be withdrawn fully and recessed in either wall. Thanks to a long truss there is no column, so the whole of the centre of the house facing the sun is potentially open. It’s a soft underbelly to a robust exterior. Off this room, which acts as the hearth of the building, there are more living spaces, guest bedrooms and offices, which are more private. This a Californian house with Fenland characteristics.

The stairwell by the main door is double-height. Upstairs the series of bedrooms is obviously more conventional and by necessity both more discrete and more discreet. Castle has prevented the spaces between from becoming narrow corridors by widening the floor at points such as at the south-east junction to create an open, shared space. This is helped by an aesthetic strategy that emphasises the corner.

On the upper floor in particular the windows are addressed to the corners, rather than the centre: it is an approach which is subtly enhanced by the way in which recessed grey steel finishes mark the junction of the flint-clad walls. Windows on the first floor are floor-to-ceiling and can slide to fully recess into pockets behind the timber cladding. Low glass balustrades are the only security when they are fully open. The building can almost disappear in the summer.

Castle has taken full advantage of the way in which the planners have been true to their mission: to enable and promote development, rather than hinder it. The result is a generosity of space and an engagement with the landscape that will develop and grow as the landscaping evolves. Indeed, although the most successful visual experience in the house is the proximity of the building’s flint and blackened larch to the garden’s oak and birch, the house as a whole is most noteworthy for its generosity and openness to the Suffolk sky.

Ground floor plan

Oak Lane House by Cassion Castle Architects

Oak Lane House by Cassion Castle Architects

First floor plan

Oak Lane House by Cassion Castle Architects

Oak Lane House by Cassion Castle Architects

Section

Oak Lane House by Cassion Castle Architects

Oak Lane House by Cassion Castle Architects

Details

Oak Lane House by Cassion Castle Architects

Oak Lane House by Cassion Castle Architects

Oak Lane House by Cassion Castle Architects

Oak Lane House by Cassion Castle Architects

Oak Lane House by Cassion Castle Architects

Oak Lane House by Cassion Castle Architects

Oak Lane House by Cassion Castle Architects

Oak Lane House by Cassion Castle Architects

Oak Lane House by Cassion Castle Architects

Oak Lane House by Cassion Castle Architects

In order to achieve the apparently simple aesthetic of black timber boxes shifting forwards and backwards on top a flint base, a strict datum line running around the entire building was established with the detailing of a range of PPC aluminium cappings.

Imagined as a subtle, simple line dividing the two floors of the house, the capping detail varies, depending on whether the timber sits directly above the flint, cantilevers past the line of the flint, or whether the flint projects past the timber, leaving a single-storey flint box.

A number of capping profiles were designed to allow for each of the conditions, with the depth and fixing details different in each case, and with further variations required where full-height windows were incorporated into the flint elevations.

A 40mm visible fascia ensured the building maintained a visually fine finish, with the capping falling towards the outside of the building to achieve this. The capping required soffit pieces in places where the windows were set back into the flint, with the capping and soffit pressing mounted either side of 18mm marine ply, and clipped together at the fascia to give them structural stiffness.

Lee Pinchback, architect, Cassion Castle Architects

Oak Lane House by Cassion Castle Architects

Oak Lane House by Cassion Castle Architects

Source: Kilian O’Sullivan

Project data

Start on site March 2014
Completion March 2015
Gross internal floor area 450m2
Form of contract JCT Intermediate Building Contract with contractor’s design (ICD05)
Procurement Traditional, by tender to selected contractors
Cost of plot £450,000 (in June 2010)
Project value £900,000
Cost per m2 £2,000
Architect Cassion Castle Architects
Client Rachel and Matthew Castle
Structural engineer Structure Workshop
M&E consultant Dragon Contracts
Approved building inspector MLM Building Control
Project manager Cassion Castle Architects
Main contractor Blackburns Construction (now merged with RG Carter Ipswich)
CAD software used Vectorworks
Annual CO2 emissions 5.05kg/m2
Airtightness at 50Pa 8.3m3/h.m2

Oak Lane House by Cassion Castle Architects

Oak Lane House by Cassion Castle Architects

Source: Kilian O’Sullivan

Specification

Ground floor external wall finish
Hand-laid knapped flints, set into lime mortar with consistently even joints. Flints laid over 100mm-thick, medium-density blockwork walls with Ancoc Stafix frame ties at 4.4 number per m2.

Steel quoins to vertical edges of flint panels
100mm x 100mm x 6mm steel angle with nine welded cleats at 600mm staggered centres. Cleats with two horizontal slotted holes for adjustment. All galvanised and powder-coated after manufacture.

Ground floor windows
Fixed, sliding and side-hung aluminium windows by Olsen Windows. Frame profiles by Sunflex (SVG99/SVG155).

Doors/floor boxes
Full-height frameless internal doors throughout. Door leafs made from hardwood-lipped solid core blanks, fitted using Geze TS500 floor springs.

First floor timber cladding
144mm x 19mm European larch. Moisture content 12-14 per cent at time of fitting, fixed to each counter batten using two stainless steel screws set out ¼, ½, ¼ across the width of the board. Finished in Sadolin Classic wood stain.

First floor windows
Bespoke timber double-glazed units sliding into pockets formed behind timber cladding. Frames stained to match cladding.

Finish to flat roofs
Polisystem UK single-ply membrane in RAL 7012 (lead grey) fully adhered to 18mm plywood substrate.

Screed/fair-faced concrete
100mm-thick exposed power floated concrete screed throughout living and circulation areas of ground floor. Fair-faced concrete to fireplace and plinth of staircase to match.

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Readers' comments (1)

  • The raised floor of the entrance area seems odd in an age when there's increasing awareness of avoiding barriers to the disabled, especially where it's difficult to see the justification - but presumably the English Building Regulations permit this?

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