Full marks for Ochil Timber

When Kinnoull Primary school needed a new gymnasium and additional classroom space the challenges facing Perth and Kinross Council (PKC) Architects' Property Department weren't hard to find.

"The school is situated in a disused quarry so is surrounded on three sides by high stone cliffs and there's only one tight point of access, making craning impossible," project architect Jana Boult explained. "The site for the gym and classrooms was occupied by a large pre-1948 timber building and one smaller modular building used as classrooms, all of which had to be demolished first. And the whole school is C listed, so what we could do in terms of design was very restricted."

Against these constraints PKC managed to design a new gymnasium building and one two-storey classroom, more or less on the footprint of the demolished buildings, using an innovative structural timber system, fabricated in home-grown Scottish timber. The new buildings are also clad in untreated Scottish larch and they sit below the height of the existing buildings, making the whole invisible from the nearby road. The different parts of the construction - classroom, gym and linking corridor - are at different levels which, said Ms Boult, "gives it a lovely, quirky feel".

PKC was also committed to providing the school with a modern building which met the highest environmental and energy performance standards - 10% over the Scottish Regulation requirements. "We wanted to wrap the building in a cosy blanket and insulate it so there were no cold bridges," said Ms Boult.

Enter Ochil Timber Ltd, the project's chosen supplier. Ochil is a Stirlingshirebased company, established 30 years ago, which manufactures, supplies and erects SpaceStud, SpaceRafter and SpaceJoist, an innovative timber construction system which comfortably met PKC's requirements on environmental and energy performance.

Managing director Andrew McAree describes his company as "specialising in the unusual, embracing innovation and technology in timber". Ochil designed and supplied all the components for Kinnoull Primary in home-grown timber - floors, walls and roofs - and used high-performance timber fibreboard insulation. In all, the company supplied 52 SpaceJoists, 40 SpaceRafters, and 210 individual SpaceStuds consisting of 736 linear metres of stud.

Key challenges for Ochil were the need to manufacture the OSB-lined structural studs to 5m and 6m heights to meet the specification for the gymnasium; and the difficulties of delivering these, and the other components, to the extremely tight site.

"We individually cut all the studs and components to size off site and delivered them as 'IKEA-type' flat packs to site, complete with full design drawings, so they could be easily erected, like a huge jigsaw puzzle," said Mr McAree.

Neil Smyth, construction manager with Morrison Construction, the main contractor on the job, said the "buildability" of Ochil's system was very helpful. "It certainly was effective in meeting the brief on airtightness and thermal performance," he said.

Jana Boult is clearly delighted with Kinnoull's completed gymnasium and classrooms: "It's a lovely little building: warm, modern, efficient and environmentally friendly," she said.

And the success of Ochil's supply of SpaceStud can be measured in the fact that the company has since supplied and erected the system for a complete school at Invergowrie.