HM Raitt and Sons
Best Use of Timber Award 2018
Bath Street Collective is a group of four families who came together to purchase the site and build a small tenement block containing a bespoke flat for each family. When the families started meeting to discuss their plans, one of the key topics of conversation was how ‘green’ they wanted the building to be. The collective wanted the project to be as sustainable as possible and they soon arrived at a brief that called for the building to be designed to Passivhaus equivalent standards of energy efficiency, with an all-electric strategy that would allow them to run free from fossil fuels.
As part of that discussion, it was also apparent that embodied energy and the use of healthy materials was important. The group was aware of Cross Laminated Timber (CLT) buildings in other parts of the UK and felt that their building, a four-storey tenement, lent itself to that form of construction.
They engaged with the contractor Egoin early in the design process and the local representative was extremely helpful in putting together some initial costs which demonstrated that the use of CLT was feasible and could be cost effective.
The CLT frame was constructed in just two weeks. Using this type of structure meant there was no need for a traditional steel frame, concrete floors, blockwork walls, plaster wall finishes and fireproofed steel. It is estimated that this saved around ten weeks in the construction programme as well as avoiding the need for additional trades.
By exposing the CLT they saved approximately 800m2 of plasterboard. Research from the University of Tampere, Finland has shown that internal timber finishes can reduce the blood pressure and pulse of occupants when compared to plaster finishes. Anecdotally based on their experience, the residents believe the exposed interior finishes help promote a sense of wellbeing.