Le Petit Fort, Jersey

Le Petit Fort is a private family residence located on the shoreline of St Ouen’s Bay in Jersey. The house has been developed and constructed within the walls of a 20th century fort which has had, along with the surrounding landscape, existing materials, and history, a significant influence on the new building’s design. A winner of the RIBA South East Regional Award 2016 and shortlisted for the 2016 Building Awards, a JCT Intermediate Building Contract was the contract solution.

Despite Le Petit Fort’s prominent location on the Jersey coastline, from the beach it is hard to see. Heavily fortified, it sits beneath the site’s existing stone walls with the appearance of a low-set watch tower – with just its first floor and central ‘keep’ (itself a reference to the nearby Napoleonic Martello towers) visible to passers-by. It has been designed very much in castle terms, taking inspiration not just from the Napoleonic Martello towers but also the Second World War fortification and the slits in the 1920s perimeter walls. The existing thick granite walls have been retained and restored and remain a focal feature. A missing fourth wall has been added, enclosing the central living structure representing the keep. Whilst retaining much of the original granite, the existing building itself was too small for a family of five and was also oriented incorrectly, with just one small window looking out to sea.

The finished house is arranged with two wings angled at 110 degrees spanning out from a central granite three-story tower block. The wings frame a landscaped pool terrace, garden and entrance forecourt within the main enclosure of the perimeter walls. The courtyard space created by the two wings within the enclosure largely shelters the pool terrace and garden from the elements. Contrary to the fortified exterior, the interior is very open; each room offers views out on to the landscape – the beach to the west and the hillside to the east.

The fort-like character of the building is most apparent from the entrance, where the Napoleonic tower and Second Word War fortification influences are highlighted. The view from the rear is less imposing and more welcoming, as the fort wings embrace the pool courtyard and garden. A main feature of the property is the stairwell running through the main tower – a helical staircase constructed out of oak and Corten steel. Viewing the entire property from above, it has the appearance of the axel of a giant hinge. The two wings intersect where the staircase and the space above it rise up through the entire tower, which is capped with a 2m tilted and frameless circular rooflight.

Corten steel, the building’s most prominent material, is used to clad the external upper levels, although it is also used inside, for the aforementioned staircase and the main fireplace. The use of Corten gives the distressed heavy-industrial effect desired by the client and the aesthetic weathering of the material is encouraged. Iroko timber cladding is also used on the exterior, breaking up the steel and creating space for the large expanses of glass to slide behind when opening up the building to the elements. Beneath, smooth polished concrete is used to clad the ground floor. Deceptively, the concrete gives the appearance of heavy cast in-situ walls, but is actually just a thin layer disguising the block wall behind.

In order to achieve the building’s aim of being able to open up to the courtyard and seascape, a robust glazing solution was required to protect it from the elements. A microclimate effect with a lot of funnelling of wind into the angles of the building also needed to be considered to make sure that rain wouldn’t get in. Shueco was chosen because it was suitable to work in an extreme maritime environment. The ground floor uses Schueco AWS 75 full height tilt-and-turn aluminium windows. Shueco ASS 70 sliding doors are used on the first floor where the two wings meet, with Shueco ASS 80 FD bi-folding doors on the first floor balcony facing west and Shueco AWS 70 windows on the second floor.

Looking inside, entering through the front door in the east wing, the feature staircase spins visitors through 360 degrees and takes them upstairs and in line with the main axis of the west wing’s reception rooms. Moving through a set of descending levels, visitors eventually arrive at the main sea-facing balcony. The master bedroom suite in the opposite wing is linked by a large landing which provides extra space to relax. The ground floor contains family bedrooms, a media room, sauna, laundry and plant room. The glass rooflight at the top of the staircase floods the space below with light. A further storey adds a guest room and a study.

A standout feature of the house’s interior is the joinery, which has all been bespoke built by local craftsman. Built-in oak cupboards hide televisions behind sliding doors while purpose-built shelving units provide storage. Full height doors in the corridors can be clipped back, and allow areas of the house to be separated, future-proofing it as the children grow up. These elements of craftsmanship are equally matched by the cast-concrete elements of the kitchen and bathrooms.

Despite being a residential building, the complexity of Le Petit Fort means that the use of the JCT Intermediate Building Contract is an ideal choice. Realising such a unique design – incorporating reclaimed materials, interesting and unusual new materials, and a large number of specialist services – requires a contract that, even on a relatively small project, can reflect this complexity and define roles and responsibilities in detail. Just as Le Petit Fort is designed to be protected from the elements, yet open and transparent, the JCT Intermediate Contract provides the contractual fortification to allow the project to be conducted in the same spirit.

Project Summary
Start:…………………………………………… January 2014
Completion:…………………………………. December 2015
Size:……………………………………………. 475m2
Cost:…………………………………………… Undisclosed
Client:………………………………………….. Private
Architect:…………………………………….. Hudson Architects
Main contractor:………………………….. Mitchell Construction Group
Structural engineer:……………………… Ross-Gower Architects
M&E consultant:………………………….. Henderson Green Partnership
Quantity surveyor:……………………….. Tillyard
Approved building inspector:………….Bob Febrache, States of Jersey
CAD software:……………………………… Autodesk Revit
Onsite energy generation:……………. Approx 80% inc. air-source heat pumps
Annual mains water consumption:.. Approx 285m3
Airtightness at 50 PA:…………………… 7.762m2/h.m2
Hot water load:……………………………. 21kW input (recovery in 1.5 hours)
Heating load:……………………………….. 23.6kW input
Overall area-weighted U-value:……. 0.333W/m2K