Ticking Truss Barn
A very long and narrow former chicken shed in an Area of Outstanding Natural Beauty has been transformed by A-Zero Architects into a new three bedroom dwelling for a family.
Speaking to PREMIER CONSTRUCTION MAGAZINE, Giles Bruce from A-Zero Architects said: “The client saw one of our projects, which also involved the conversion of a barn, and they contacted us off the back of that to see if we could help them with the project, which was originally a chicken shed. We have quite a bit of experience in this area and learnt quite a lot from the last project so it was certainly something we knew we could do.
“The brief was to try and work with as much of the existing structure as possible and to come up with an exciting architectural version of what had been a very generic and agricultural building.”
The original barn was a very simple construction, with concrete slab and block walls, weather boarding and timber trusses. A-Zero reused a good deal of this fabric in the new construction, whilst upgrading the whole envelop to current standards.
For the new roof structure, the architects opted for a scissor truss to maximise the ceiling height at the centre of the space. Constructed from a combination of glulam and steel ties, eleven trusses are all subtly different, introducing a structural rhythm along the length of the space. This is achieved by varying the angle of the steel tie at each structural bay, not unlike the ticking hands of a clock.
“Because we were working within the original envelop of the building, we went for a particular type of truss,” said Giles. “We used a scissor truss and the reason we did that was to give as much height to the middle of the space as possible. It is a very long space and it would have been a very low space had we used a conventional truss; that Scissor Truss gives the space the height it needed.”
The brief also called for both privacy and openness from the adjacent field. This was achieved through slatted screens and deep reveals. These strategies also served to reduce solar gain, which was a consideration for the west facing site.
As a self-build construction project, one of the main design questions was how to simplify the build in a way that could be done safely with the minimum amount of plant and equipment. The architects used a series of physical models and diagrams to communicate the construction strategy to the teams of carpenters who built the structure, and these models were also helpful in informing constructional sequence of the build, in particular air tightness membrane, which was a key part of the environmental strategy. The building is heated by a biomass boiler, with low energy demand which is achieved through MVHR and excellent air tightness levels.
Giles said: “The client was very positive about the project and they were very pleased with the final product. Our practice has a strong focus on environment and I think with this project that translates to reuse. I think it is great to take a building that was not being used and re-use so much of that original fabric to reimagine that building and bring it up to a level of performance which is so far beyond current building regulations. It shows that you don’t really need to buy new things but you can reuse what you already have.”