Even on a grey, damp autumn afternoon the bare skeleton of the Scottish Ornithologist's Club's (SOC) new headquarters glows with the special warmth of real wood. Rafters were being fixed to the massive post and beam frame when NCE visited the site last month, using traditional pegged and tenoned joints. Originally, says architect Simpson & Brown associate Jenny Humphreys, green Scottish oak was specified - 'but a much better option emerged when the Forestry Commission got involved.'
Instead of oak the Forestry Commission proposed to use of some of its prized 100 year old Douglas Fir (see box), which could provide the large sections needed. And since, as a sponsor of wood. for good. , the Forestry Commission also proposed to donate the timber to the project, SOC was only too happy to agree.
So was the architect. 'The Douglas Fir gives a much warmer feel than oak, ' Humphreys explains.
Large cross sections increase fire resistance - but no kiln is large enough to dry the Aberlady timbers, which range up to 9m long and 375mm by 250mm in cross section. And it would take several years for the timber to dry naturally. Specialist frame designer and constructor Carpenter Oak and Woodlands production manager Steve Lawrence, however, says this is no real problem, provided the joints and the design details take long term shrinkage into account.
'Frames made from green timber actually get stronger as they slowly dry. The only problem we've had is that some of the purlins warped slightly during the six months they were lying in our yard.'
His company specialises in heavy timber and works almost exclusively with home grown timber and local sawmillers.
For this project it produced the 'log list' for the sawmill (one of the few that could handle 9m long logs), planed the sections, cut the joints and predrilled the peg holes.
The only protective treatment the timbers receive is a coat of raw linseed oil and turpentine, mixed 50:50. 'The only metal connections are at the apex of the roof angle where the two wings meet, ' Lawrence reports.
'And there's only two of them.'
Sustainability is the key word throughout the project. Even the much needed insulation in the building envelope is recycled car windscreen glass, donated by Superglass Insulation.
This will help achieve one of the SOC's key design briefs - a building which is easy and inexpensive to maintain, heat and manage. According to wood. for good. managing director Charles Trevor: 'this project celebrates Scotland's indigenous materials - particularly timber. It shows that the most traditional of materials can be used to create contemporary, relevant architecture.'