Astonishing simplicity of the cork construction
Matthew Barnett Howland is an Associate Professor at The Bartlett School of Architecture UCL and Director of Research & Development at CSK Architects. Together with Dido Milne and Oliver Wilton (UCL), he designed the Cork House in Berkshire, UK. The house, which was shortlisted for the RIBA Stirling Prize and has won The Stephen Lawrence Prize, a RIBA National Award and the RIBA South Sustainability Award, is a brand new and radically simple form of plant-based construction. In this interview, Matthew explains the fundamental principles of this project and also some of the benefits of using cork in architecture.
Could you start by explaining how you began your research on the use of cork in civil construction? What motivated or inspired you?
Matt: It comes from an ongoing dislike or dissatisfaction with typical modern construction systems.The complexity of these systems makes the end of the building's life particularly problematic, whereas the materials should ideally reenter the flows of the material life cycle. Our research concentrates on preserving material integrity through the assembly. Then, at the end of the building's life, we will see that it makes it much easier to reuse those materials.
Furthermore, those complex envelope systems are made of products rather than materials (usually cement-based, petrochemical, or high-carbon products). It makes it very difficult for the designer to really understand what it is that they are putting together and its impact on the landscape, workplace, or carbon emissions. I am much more interested in architecture made out of materials than one made out of products. For me, it is just about making a really simple assembly of materials. It was never really specific about cork, strangely. The cork was a sort of means to explore those ideas.
Why, among many bio-based materials, did you choose to work with cork?
Matt: We wanted one material to perform all the functions of the building's envelope. With cork, it is possible to achieve.. We are trying to use it for the structure, for the insulation, for the finishes,and for moisture transfer. It fulfills all of those functions. It also has some amazing qualities and creates a very particular environment: the way it works with acoustics, light, and smell creates a special atmosphere that is not like any other material in that sense.
Cork also comes from a lovely landscape around the Mediterranean that has rich backgrounds, both environmentally and socially. It is a part of a very old and rich human-shaped ecosystem culture. By specifying it, you are helping the economic viability of the region, helping the hydrological stability of the forest and the soil.Working with materials like cork, is a very good start for the building life cycle. Especially if designed intelligently so that those lovely characteristics are preserved until the end of the building's life. After that, the best thing to do is to reuse all the parts. The next best thing is to make sure that they are easily recycled with not too much energy required or too much difficulty. hat is good about the cork is that if you can’t preserve it, it can go straight back to the soil and regenerate.
Can you explain the principles of this construction system that you have developed ?
Matt: The idea was to use cork as much as possible in the construction system. But it is also supplemented by timber. We can split the system into two: all vertical load is taken through the cork and all horizontal load through the timber. Any other material used in the building (air tightness in the joints, kitchen fittings, etc.) has to be as unprocessed as possible, preferably plant-based.
And most importantly: independent of other materials, so that it could be removed, disassembled, and replaced without compromising other materials around them. So the foundations are steel screwed parts that are removable. All timbers are bolted together and all the fixings are exposed, including the floorboard fixings. Everything is easily accessible.
And this construction system is composed of cork blocks. How is the assembly of these elements? Is mortar or glue necessary?
Matt: No, the whole construction is dry-assembly. It works through gravity: the roof light on top is like a little paperweight. After that, self-weight takes over together with the friction in the joints (there is a tongue and groove system, quite a simple idea). The =core concept behind the project was simplicity.
So it doesn't require any skilled/ special workforce? Could it be easily assembled by the local workers or communities?
Matt: It could be assembled by me . I assembled it. All the different elements were drawn in CADand were sent to different workshops. Cork and timber elements were made in Estonia, and roof lights in Germany. Later everything was sent straight back to the site. So no warehousing and no intermediaries. And it was all designed so it could be assembled by me. So,a semi-skilled workforce is needed.
How are the cork blocks produced?
Matt: They are made in Portugal and shipped to the UK, where there is a 5-axis CNC machine to make the tongue and groove fit.
The blocks are made with a lower-grade cork that can´t be used for other manufacturing, like wine bottle stoppers. There is an industry at the end of the chain that makes so-called “expanded cork”. That cork is cooked. The natural resin in the cork melts about 360 C,which bonds all the grains back together in this 100 % bio-renewable, plant-based engineered product. It is really unusual material!
What is the estimated lifespan of cork? Matt: Amorim (the cork manufacturer) says that cork in a building could perform very well for more than 100 years. I think it will probably be like timber. There are timber buildings that last hundreds of years if they are well detailed and protected. But it is difficult to say. In our project, it is used as a breathable wall construction. In theory, it should be fine. But the truth is, we will find out in fifty years, and we will see how it is doing.
Can you explain a bit about the concept of the Cork House?
Matt: I guess the best way of describing it is through this phrase : “form follows lifecycle”. It reflects the idea that architectural space and form can be driven by lifecycle considerations. We chose cork for certain physical characteristics, but also ecological reasons. Then we found out the best way of making a building with that, that respects the whole lifecycle. Finally, that sort of system thinking generated an architecture for us. So rather than designing something and then trying to make that as “sustainable as possible”, we do it the way around. Weu design a sustainable, regenerative life cycle, and the architecture arises from this thinking process. For example,the pyramids on the cork house are the results of a whole set of factors that generated the form. We didn't draw that form and then said lets make that form. It comes out of an understanding of cork and the fabrication and assembly process. So it enhances the phrase “forms follow lifecycle”.
The Cork House was inspired by ancient stone structures. Do you often take inspiration from vernacular architecture to design your projects?
Matt: I guess in the sense that it is useful to reflect on vernacular architecture and why they are how they are. I am not interested in vernacular architecture just in terms of how they look.I think the most important is that those architectures come out of careful management of resources and energy. That is why it is interesting to analyze why they are how they are.
Do you believe this type of traditional architecture has an important role while talking about sustainability?
Matt: Yes, Absolutely. Without being stuck in the past obviously. There is a different context now, with totally different circumstances and technologies available to us.But the fundamental relationship between architecture,culture and natural ecosystems is still the same.
What are your plans for the future? Are you going to further the research with cork or work with other natural materials to develop new construction systems?
Matt: Currently,we are working with a German client in Hamburg, developing a cork warehouse construction system. It is taking some basic ideas of the cork house but trying to develop them into a much more standardized kit of parts. Our objective is a
a more standardized, more applicable, slightly more cost-effective system. We focus on greater material utilization with much more efficient machining. And we are also working on a quite big Hempcrete project for a farm, where they are going to grow the hemp on the farm. It involves the cultivation of hemp from which farm workers will make a building with a timber frame.Our practice is gradually going in that direction. We are creating an ideal of the relationship between architecture and landscape. At the center of our interests is
the relationship between the building lifecycle and the material planetary systems that everything relies upon.From the lithosphere, which is basically rock, to the biosphere (timber, cork, hemp , etc.), and the pedosphere (mud and earth). We are also doing a couple of stone projects. Stone is an interesting circular, bio-renewable product to me. It can last thousands of years and be used in many building life cycles.
Most of the projects I mentioned are part of a collaboration between research and life projects in practice.
Author: Danielle Khoury Gregorio
* Article originally published on the website bambouimmobilier.com