Dune House, Thorpeness, Suffolk

Introduction

In 2010 the writer Alain de Botton, author of The Architecture of Happiness, introduced Living Architecture, a not-for-profit holiday rental company. His aim was to promote world-class modern architecture and to enhance the appreciation of architecture by giving people an opportunity to experience what it was like to live in a space designed by an outstanding architectural practice. Several holiday houses are now available to rent, including Shingle House at Dungeness, a previous TRADA Case Study. Another holiday house now available to be let is The Dune House, just to the south of Thorpeness on the Suffolk coast; the area has an eclectic and eccentric character and had long been a favourite holiday destination of de Botton.

A beach holiday is about being connected to nature. Facing the North Sea, with glazed walls and a dramatic roofscape created from cross laminated timber, Dune House is set on one of the few inhabited stretches of beach in England, nestling among rolling dunes and with panoramic views of the sea from terraces, bedrooms and bathrooms. It replaces an original two-storey chalet bungalow which had been extended in an ad hoc fashion during its 100 year life and suffered from serious structural problems.

Jarmund Vigsnaes Arkitekter, a highly regarded architectural practice from Norway - on the other side of the North Sea from Thorpness - was selected as architects for Dune House by means of a short competition process in 2008. Mole Architects were brought in at the start of the project in a collaborative capacity and were involved in obtaining pre-application planning permission, detailed planning permission and Building Control approval, with increasing involvement as the project progressed. The site is on the edge of a conservation area and in an Area of Outstanding Natural Beauty. Mole Architects made an early start in consulting and negotiating with conservation and planning officers and produced a robust Design and Access Statement. To achieve planning consent it was important that the new house related to the original house and to the typically British seaside strip of houses nearby. Like them, the new house has a simple rectangular plan and a pitched roof but these elements have been reinterpreted in an entirely modern way, using innovative modern materials and technology. The roofscape is the key aspect of the design – its pitched form reflects local vernacular gables and sheds but it is also an exploration in geometry, creating a dramatic and exciting profile. This transformation was made possible by the use of cross laminated timber structural panels.

 

Materials and construction

The house is slightly sunk into the dunes to provide a sense of privacy and a measure of protection from the wind coming off the North Sea. The ground floor, a cast in-situ concrete slab on a concrete raft foundation, is a large, open plan space - a living area, dining area and kitchen. The concrete floor has a polished finish and the ceiling is lined with natural ash strips. At the heart of the open plan ground floor is a cast in-situ concrete core housing staircase, storage, plant room, wc and an en-suite bedroom; it also supports the chimney to the woodburning stove and was cast with a shallow recess as a bookshelf; a larger, deeper recess on the other side encloses kitchen units and the cooker with its air extractor above. The board marked finish of the concrete core is exposed. The concrete core, in combination with slender steel posts at the perimeter, supports a projecting first floor concrete slab.

The walls are entirely glazed, with glazed sliding doors at each corner, allowing the space to open equally, giving panoramic views in all directions and emphasising the floating appearance of the upper floor.

In contrast to the concrete, glass and aluminium of the ground floor, the first floor is a complex series of tent-like pitched roof forms, enclosing four bedrooms with en-suite bathrooms and a landing/library space with a glazed screen which gives access to a small roof terrace. Bathtubs are placed in bedrooms rather than bathrooms to take advantage of the views from the windows.

The geometry of the first floor is complex; the north and south elevations are largely vertical gables while the longer east and west elevations comprise double gables; the elevations connect at the corners with irregular, triangular facets and slope in a series of peaks and folded planes. As a result the bedrooms are triangular in plan but the high sloping ceilings give a sense of space while all the beds have a view – the gable walls are fitted with Velfac composite aluminium/timber windows. The bathrooms are also triangular in plan and fitted with showers.

Externally the vertical gables are clad with vertical dark stained Scandinavian whitewood boards to match local vernacular houses and fishing sheds. The pitched roof forms which connect the gables are all clad with tinted and textured stainless steel shingles.

The complex geometry of the first floor was made possible by the use of cross laminated timber panels, designed and supplied by Eurban. The cross laminated panels, either 100mm or 120mm in width, were delivered cut to size, with edges profiled to create the required angles of pitch and with window openings already formed. As a result they were erected on site in only three days. The panels were fixed to the concrete slab with brackets and screwed together. A breather membrane was then laid over the panels to give temporary protection from the weather. They were then overlaid with 175mm thick 0.3mm gauge steel-lined Kingspan SIPS sandwich panels, of the type generally used in cold store warehouse construction. The pitched roof elements were clad with a bituminous waterproof membrane and 500 x 500mm stainless steel shingles, fixed directly to the Kingspan panels. The vertical gables were clad with breather membrane, battens and counter-battens and 44 x 19mm vertical timber boards. This resulted in an extremely well insulated and sealed construction.

The upper floors are of timber joists acoustically insulated from the concrete slab they sit on, and floored with ash boards. The secondary floor was necessary for service routes. The interior faces of the cross laminated timber panels are treated with a transparent fire-resistant coating and exposed to give a warm and welcoming feel. A light wash of white woodwax oil was used to avoid a ‘Scandinavian sauna’ aesthetic. Eurban also supplied 30mm thick linings and sills to glazed openings, to match the exposed timber walls and achieve acoustic separation between bedrooms.

 

Sustainability

The house is designed to achieve a 20 per cent improvement in energy efficiency compared to current building regulations and the cross laminated timber contributes to the improved energy efficiency. The house is fitted with a 7,500 litre grey water tank and a mechanical ventilation and heat recovery system.

The raw material used in the cross laminated timber panels is solely certified timber from sustainably managed forests. Only formaldehyde-free adhesives are used for bonding. An integrated sawmill and manufacturing plant helps reduce raw material transportation and is a natural benefit for quality control. Cross laminated timber panels help regulate indoor climatic conditions resulting in healthier indoor environments. They are reusable, recyclable, and easily disposable as biomass fuel.

Completion Date:

December 2010

Year Published:

December 2013

Building Type:

Holiday house

Location:

Thorpeness, Suffolk

Owner/Client:

Living Architecture

Architect:

Jarmund Vigsnaes, Arkitekter and Mole Architects

Structural Engineer:

Jane Wernick Associates

Timber Engineer:

Eurban

Main Contractor:

Willow Builders

Timber First Floor Walls and Roof Structure:

Eurban

Timber Floors:

Whippletree Hardwood Flooring

Timber Elements:

First floor walls and roof structure, cladding, flooring

Timber Species:

Spruce, ash, Scandinavian whitewood

Awards:

RIBA Award 2012 RIBA Manser Medal 2012, Shortlist Wood Awards 2013, Shortlist

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