13 December 2017

Grand Designs’ County Down Barn: A transformation using CLT

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Architect Micah Jones has used cross-laminated timber (CLT) to transform a dilapidated agricultural building into a luxury interpretation of the farm buildings of his rural County Down childhood, pioneering this method of construction in Northern Ireland.


The County Down Barn, which featured on Channel 4’s Grand Designs last September, is a contemporary take on a traditional barn conversion formed of a one-storey CLT structure installed above the restored original stone building.


The new home was built on a limited budget and timescale, and is located on a tight site with stunning views across the Mourne Hills. By using a complementary material palette of CLT, stone and concrete, Micah has provided an elegant yet comfortable and robust home for his growing family.   


There were several reasons for the specification of CLT, including the material’s enhanced thermal and air tightness performance - a major benefit as all the insulation on the house is external. Other key considerations were CLT’s structural ability to achieve the clean, long spans that Micah was looking for and the material’s high-quality finish, which was important because internally the CLT has been left exposed throughout.


The Barn is laid out as an upside-down house with the main living space on the first floor and the bedrooms at ground floor level. The house is long and narrow, and Micah has designed the CLT upper floor to create a ‘tunnel of timber’ effect, formed of one long open span. This has been achieved by an ‘over-truss’ solution developed for the project by CLT specialist G-frame Structures. “It was an innovative way of installing the structure and has allowed us to create a very open, modern barn conversion,” says Micah. “The trusses are placed on top of the roof and the roof is ‘hung’ from them so that only the tie beams are visible internally, instead of the traditional triangular trusses placed every few metres, which would effectively close down the space.”


Micah has used the CLT off-cuts from the windows and doors to form the staircase which links the ground floor sleeping areas to the living space.  The staircase narrows gradually from the bottom until it arrives at the centrally located first floor landing or ‘hub,’ which acts as a family room with a mezzanine play space above. To one side of the hub, at the top end of the house, is the kitchen, dining space and living area or ‘snug’ which is all formed of one space. Another, quieter living space is located on the other side of the hub, and from here the full length of the house can be seen with the surrounding landscape visible through the doors at the far end.


The County Down Barn is Micah’s first project using CLT and has pioneered this method of construction in Northern Ireland. “CLT is a new product in Northern Ireland, but I’d seen it talked about on some of the architectural websites and I knew that I really wanted to use it,” he says. “I had tried previously to move forward with it and not got very far so I’d had to look at other options, but I kept going back to CLT.”


“The most important thing to do if you want to build your home with CLT is to work with a quality manufacturer and an experienced and reputable CLT installer,” he says. “Once you have the CLT installer on board, all the other elements such as getting the structural engineer fall into place.”


Micah made contact with CLT manufacturer Stora Enso UK who introduced him to G-frame Structures, one of their UK delivery partners who also have an office in Ireland. “It was fantastic working with Stora Enso and G-frame. Stora Enso took myself, my wife and the Grand Designs production team to their impressive CLT mill in Austria where I learned about the complete manufacture process.  I now have a deeper understanding of what can be achieved with CLT in terms of structure and design.”


“CLT is a fast, efficient method of construction,” says Micah. “It took just five days and one delivery to install the CLT structure. The G-frame team arrived on the Sunday and installed connectors, the CLT panels were delivered on the Monday morning, and by Friday the CLT structure was complete and the G-frame team packed up and left.  Also, our site is up a long, winding lane with several sharp bends and these site constraints prove that with a little planning CLT can be used wherever the truck can get to.”


The County Down Barn is Northern Ireland’s first completed CLT building. It has set a precedent with NI Building Control which it is hoped will pave the way for people wanting to build with the material in the future, including a fire engineered solution which allowed the CLT to be left exposed internally.  “This was good news as the CLT creates an incredibly warm and welcoming space, and we wanted to keep it totally natural internally,” says Micah. “The house isn’t a monument to architecture. It was more about building a home that could take the abuse of daily life and survive it. The wood is versatile and forgiving - if it’s stained from UV light within a month, it will return to its natural colour and because it’s structural we’ve been able to do things that would have been impossible otherwise, such as hanging a swing from a beam and slinging a large cargo net between a CLT floor slab and a beam. The kids love it.”


Offcuts from the CLT panels have been used to make the breakfast bar and kitchen table as well as the wood store in the main living area, meaning that there is no waste material. Micah has also used concrete comprehensively in the design and it contrasts well with the CLT and stone. The floor throughout the upper level is a polished dark grey concrete and the polished concrete kitchen worktops were cast in place. “We love the way the concrete and wood complement each other,” says Micah. “Wood has an inherent softness and warmth, and concrete has the opposite—but they work really well together.”


On the ground floor are four bedrooms, a plant utility room and a bathroom which has been hand crafted by Micah using local green ash cut into narrow 2” strips which he steam bent himself. The wood has been treated with two coats of UV Protection Oil for protection against splashes and to bring out the grain. “People don’t think about using wood in a bathroom because they assume it won’t be suitable, but provided there is adequate ventilation it is OK,” says Micah. “We have whole house ventilation with heat recovery providing a constant flow of air and there is no issue”.


The bathroom floor is natural stone and the stone resin bath, which Micah found locally, is sculptural in form and goes well with the steam bent wood. The stone troughs from the barn have been re-used for the wash basins.


Externally, the stone from the original building has been re-used to clad the ground floor. A courtyard at ground floor level and a garden which is accessed from the first floor provide outdoor space.