Alex de Rijke admires the creativity and commitment in a self-built experimental house by Matthew Barnett Howland with Dido Milne and Oliver Wilton
Building a house made of cork might sound like a fairy story, like a gingerbread house. Or like the more familiar but inedible architect’s fantasy, the house made of glass, of which there are a great many examples. But the Cork House project by Matthew Barnett Howland with Dido Milne and Oliver Wilton is not an example of pursuing a subjective idea, or an indulgence of patronage. The architects have, as an independent initiative, analysed an old material and explored modern ways of using it, presenting the building as a didactic offering to the construction industry.
Cork House is not merely clad in cork externally, insulated with cork invisibly, or lined in cork internally. Several examples of deploying cork to improve the thermal performance or the character of a more conventional construction exist around the world, and particularly in Portugal, home of the cork oak tree. But this is a house made almost entirely of cork.
I make this distinction as an advocate of timber architecture in a market sated with rhetorical examples of ‘timber buildings’ which are actually steel or concrete frames clad in wood, or a timber structure clad in brick. With global construction materials and methods increasingly criticised for carbon emissions, here is a unique example of an experimental house using only the bark of cork oak trees as solid structure, insulation and finish, inside and out.
As a research project the commitment was always going to be greater than the funding, so for the architect researchers it meant building themselves something useful. A dog-kennel-scale prototype, followed by a larger module tested with Arup, developed both detail and ambition to eventually become a dedicated small house project in the back garden of a house next to the Thames in Berkshire.
But the building is not just a lesson in sustainability, like a research thesis made three-dimensional. It is a beautiful house, built with imagination and rigour, using a robot offsite and by hand in-situ. And the result of this six-year-long process is redolent with a particular quality of calm delight; partly due to the power of the material, and partly the evidence of the pleasure of making.
Standing inside, one can recall the architecture of Kahn or Soane in an enfilade plan of top-lit rooms. These repeated tall volumes, each with their oculus, and arranged in a row, create a choreographed sequence of spaces, from porch to bedroom. Externally the five repeated forms make a mock-monumental site boundary, effectively screening the garden from a neighbouring waterworks. The risk that a corbelled compression structure, made of a dark, sound- and light-absorbing material could become tomb-like has been skilfully avoided. Timber, glass and brass internal detailing all combine to enliven the daylight and acoustic qualities. The direct inspiration of stacked stone structures has here been symbolically transformed, celebrating life over death; a grown material arranged to give ongoing pleasure to the inhabitants, with the promise of another use in future.
Like Aldo van Eyck’s structuralist work, the visitor feels that the design agenda has not only been intellectually consistent but deliberately humanising. Warm cork is way sexier than concrete block, however, and doesn’t need additional cement, insulation, paint et cetera.
Eton town and neighbouring Windsor Castle are defined by the eponymous private school and monarchy respectively, bastions of British traditionalism standing either side of the ancient Thames. It is perhaps the last place one would expect to be a site of modernity. Yet British culture has always excelled not only in eccentricity and individualism but experiment and innovation. Departing from the tradition of romantic empiricism, the back garden ‘laboratory shed’ model has here been replaced with a more methodical, self-critical and refined testing of an idea now realised, documented, and due to be monitored in use.
The architects, supported by Arup’s engineers and The Bartlett’s workshop, have constructed a small but precise manifesto for a completely different form of sustainable construction. The message is clear: a building made primarily of one renewable material, and only one layer thick. An old timber crop made modern. An assembly of digitally prefabricated blocks, with integrated hand-crafted components but no wet trades; a demountable, recyclable composition. A UK design demonstration of the potential of a carbon negative material for a world looking for more answers to climate change.
One could be forgiven for thinking that the Cork House, confidently poised on its mini-piles above the damp riverbank grass, is buoyantly looking forward to inevitable floods; to floating away to the future with an ‘I told you so’ nonchalant backward glance to the drowned brick of conservative England.
Matthew Barnett Howland, Dido Milne, Oliver Wilton
Our research on building with solid cork commenced in 2014, part-funded by an Innovate Voucher from Innovate UK, with material donated by Amorim. Initial design and prototyping work was underaken at The Bartlett School of Architecture, UCL.
This started the investigation of using solid expanded cork blocks, made of 100 per cent cork granules from cork oak forestry, to create a form of block-based construction. There were a number of motivations for starting the research, including a desire to extend the application of this plant-based material, which has been in use for millennia, to create a simple form of construction based on cork stereotomy. This rudimentary early research helped to determine the potential for this approach and informed the subsequent main research project.
Detailed research, testing and development of the cork construction system was undertaken from 2015 to 2018 by MPH Architects, The Bartlett, University of Bath, Amorim UK and Ty-Mawr, with subcontractors including Arup and BRE. The work was part-funded by Innovate UK and EPSRC grants under the 2015 Building Whole Life Performance competition. The funding gave the opportunity for in-depth research with the aim of developing a viable cork construction system with outstanding whole-life performance and using a dry-jointed interlocking block system for simple assembly and disassembly.
The research included much design hypothesising and preliminary prototyping, and the development of a robotic milling technique at The Bartlett used to form the blocks. Test panels were made and lab-tested with regard to a range of performance criteria. Work at the University of Bath focussed on structural characterisation testing and the BRE undertook tests relating to fire performance and rain-tightness. A small test building was created, in which air pressure was monitored to help establish performance through the seasons under actual weather conditions. The research ascertained the viability of the cork construction system for a range of applications.
The Cork House utilises an evolved version of the cork system, tailored to the site and to the particular aims of the project. It uses 1,268 cork blocks, manufactured by Amorim in Portugal and then fabricated using a five-axis CNC milling machine in Suffolk. These blocks carry all the vertical load down to the solid timber floor, and timber eaves beams and structural CLT wardrobes play a role in taking lateral wind loading. Services are integrated via ducts in the CLT floor and wardrobes.
A whole life carbon assessment of the Cork House undertaken by Sturgis Carbon Profiling calculates that the house is carbon negative at completion, due to the atmospheric carbon locked up in its cork and timber structure. The assessment indicates a whole life carbon of 619kgCO2e/m2 GIA, the lowest of any building assessed by the consultant. A post-occupancy evaluation of the house, to be undertaken with the Bartlett, will commence over the summer and run for 12 months.
Having undertaken the research and completed the architectural project, next steps under consideration include further research and development of the cork system, including work on standardisation and moving towards a marketable construction system. Discussions are also underway on further architectural projects that use the cork system and also cork timber hybrids.
Matthew Barnett Howland (original concept) with Dido Milne, Oliver Wilton
Whole-life carbon assessment
Sturgis Carbon Profiling
Component 3D modelling
Structural Accoya and spruce CLTt
NFP Europe, SBM Fastwood
Accoya doors and windows
Whyte & Wood
The Rooflight Company