all photo’s Oliver Lowenstein, Fourth Door Research
Gloucester’s Wynstones school ‘new hall’ project has reclaimed the Belfast truss, a former barrel vaulted wooden roof structure that disappeared after World War II.
This July, the Waldorf Steiner school, Wynstones, completed the second stage of its unique school building project, preparing and raising their new timber frame school hall. One of the UK’s older Steiner schools, seven miles from Gloucester, this second stage of the new hall project has been remarkable in showing just how participatory an initiative such as this can be. During the first week the whole school pitched in, while for the next three weeks a diverse band of volunteers cut, sawed and hammered it’s way to raising the timber frame amidst this years wet, wet, wet summer weather. All this was overseen, guided, and from time to time, cajoled along by a small team of carpenters who had converged on the school to lend their expertise to the enthusiastic though inexperienced crew. And not only was the level of hand’s on involvement unusual for schools in this country, but the timber frame structure they worked on and raised is a first, those running the project believe, for at least fifty years. The Belfast Truss was a popular timber structure system towards the end of the nineteenth century before disappearing in the aftermath of world war two.
It wasn’t always going to be this way. The school had for several years been planning a new hall on the edge of its playing fields. Originally the schools new hall steering committee, albeit with a certain heaviness of heart, had in 2002 directed an architect to prepare initial plans for a bog standard steel frame industrial shed. Fundraising had been ongoing for quite some time but funds thus far were not exactly over-brimming, and the committee – focused around parents, Charles Crittall and Richard Fox, although wanting a green building – saw this as the only way forward. Building a big metal box also grated with the Steiner school ethos, with its emphasis on the natural, organic and traditional craft which threads its way throughout the curriculum.
Before they got this far, though, chance – or design – intervened. Henry Russell, a carpenter of long experience, had been working for another school parent, who told him about the new hall project. Russell, it so turned out, had been at Bedales School, another node in the one time progressive schools network. Bedales, also, historically emphasised the hands as much as the head, and as a pupil kindled in Russell an enthusiasm for wood and buildings, including the re-construction of two timber frame farm barns on the schools grounds. After leaving he gravitated back into carpentry, and has since become something of a font of wood and carpentry knowledge, being one of the driving forces of the annual Frame timber-framing conference weekends. A part of his reservoir of wood knowledge he was aware of a cheap and elegant structure, the Belfast Truss barrel roofs. Also in 1995, during a seven year stint at Carpenter Oak & Woodland, Russell had returned to Bedales to do exactly what was now being proposed for Wynstones, getting the whole school involved in direct, hands-on building. That time, too, the building had been a new hall, FeildenClegg’s Olivier theatre, which once completed was applauded for its timber detailing and was a high water mark in the practices arts and crafts phase.
The fortuitous connection with the parent led to meetings with, first Crittall and from there, Richard Fox. Russell told Fox about Belfast Trusses, essentially a variation on the barrel vaulted roof. This included their extensive late nineteenth century use; how they were both comparatively cheap and simple to construct and could also cover wide spans, in Wynstones case 18.6 metres was required (which is and sounds impressive though paling in comparison to trusses capacity of up to 30 metres.) Henry also recalled the previous experience at Bedales. And only a few miles away, across the other side of the River Severn in the Forest of Dean he knew of a wood mill, which could provide very good quality, and well-priced Douglas fir and other timber for the job. Fox’s eyes were probably lighting up at this; not only was this so much closer to the heart of the Steiner educational ethos, but the economics were such that it was actually potentially realistic to go with.
Russell was excited because here was an opportunity to build a structure he’d long wanted to try his hand at; a host of timber carpentry experiments could be tested by the building. He thought very little steel would be needed. Crittall and Fox were excited because here was a way out of their steel box cul de sac; the economics stacked up, just about; and it could involve the whole school. So much more to the educational way of doing to which they wanted to adhere.
In the meantime Crittall and Fox had found another architect, a Hants CC with schools experience, although the changing brief was quickly passed on to a colleague, David Gregory. Gregory brought in Romsey based engineers Andrew Waring Associates with Nigel Chalice from their team getting involved.
Architect and particularly engineer, cautious at Russell’s all timber, steel free claims, revised the plan, in effect combining two designs; the modern steel frame with a more traditional timber truss structure. In so doing a significant amount of steelwork was added to the plan, partially, it seems as health & safety insurance. At each end extra steel bays were added, bookending the nine latticed trusses, separated by bays, each 3.6metres apart, while along each side of the building are further single floor 4 metre high floor post and beam aisles. Seeing the hall immediately after the frame had gone up, I was unprepared for the sheer scale of the building, reaching a height of 9.6 metres. Added into this is an intermediary mezzanine level will be built in at one end. Russell now acknowledges that the additional steelwork is quite an important part of the structure, ensuring the timber frame won’t (and can’t) wrack in either direction. Inevitably, he acknowledges, this makes for a much more stable building, particularly with a rigid steel lattice within the roof plane, running laterally, along the buildings spine. Still, the hall, covering around 2250 sq metres is a sizeable and ambitious project.
When the time arrived to order the wood, sourcing the complete required amounts from his forest of Dean mill, Woodgate, was more complicated than anticipated. Woodgate eventually supplied between a third to a half of the buildings Douglas Fir and Larch. The remainder was supplied by Vasterns, British grown C16 graded Douglas Fir, which had been kiln dried. Ungraded timber was used on the larger sections and on the stud panels.
The early work was carried out by the whole school during the last week of term, with over 70 pupils, divided into teams, working on specific parts of the whole building. The first two trusses were completed in that first week and parts for most of the majority of the remaining trusses were started. Also during that first week the aisle walls post and beam frame was prepared and scarfed together. Other post and rails were prepared with 22 morticed and tenons, as well as many of the stud panels.
The next week the volunteers arrived, a mixture of parents, friends and others who had had about the project, through the schools grapevine, (including myself and my son) as well as a sizeable contingent of German Waldorf school teenagers. Both Russell and the school had invited specialist carpenter colleagues to lead the nine or ten teams, one by Russell’s old friend and Carpenter Oak and Woodland founder Charley Brentnall. Three weeks later the second stage was completed on time, despite much of time being wet and sodden. By week four, when I turned up, much of the work was completed, with the last trusses being finished off, the post and beams being manoeuvred into position ready for raising, before the heavens opened again and 24 hours later much of Gloucestershire being declared a flood emergency area. The main team, plus a reduced number of volunteers ploughed on, into the last week when the crane arrived and the whole build went up, still on time, and without too many mishaps.
Russell was particularly interested in how both this low tech and non-specialist truss construction process could provide a long span girder covering considerable areas, and that part of that process, the external top and bottom chords, in effect, carry out the trusses work. These trusses are 2.6 metres high at their ridges, with the web lattice section joined to their external frame – the upper and lower chords. He loved how both these top and bottom chords – using short panels of ungraded wood, “ could be simply nail laminated onto the lattice section, a piece of carpentry easily carried out by the unskilled volunteers. Similarly, the next step, of the upper chord being bent round a jig was straight-forward, bowing the chord into the barrel arch shape, introducing the compression element to the truss. Once completed the chords carry the trusses load, its weight extended to the trusses eaves, while the lattice web strengthens each of the trusses stability, in all a relatively uncomplicated process. Lengthwise the hall is about 120m metres, with the 7.3 metre 22 posts on each of the structures two sides sitting on galvanised steel shoes, within the concrete slab. At each end stands the extra steelwork added in by the engineer.
As each of the trusses were completed, with its different layers fixed together, the team literally lifted it off the jig with small dollies before starting the next one. With volunteers, the trusses were completed in a day and a half, through very low tech processes. Russell thought that professional carpenters using power tools, would bring this down to one day. Also, as it was, Russell believes, using a Belfast Truss reduced the amount of wood by about a third. He could also see that a comparable traditional timberframe building would use significantly more steel.
Once up, all those involved were very pleased with the result and Russell particularly believes, that the Belfast Truss could be an effective wide span timber frame exemplar to push today in the early 21st century. Noting how ubiquitous truss roofs are in the mass housing market, and their re-emergence in the larger buildings, he points out that durability remains a problem, something a structure such this, using the right wood, could effectively help.
Their history goes back to the mid 19th century when the lattice truss was first developed. The Belfast truss is an adaptation of two earlier structural systems; the lattice and bowstring trusses, this latter so called because of its arched form. Belfast trusses began to be built at the end of the century and continued to remain competitive because of their cheapness compared to steel, particularly during world war one, as steel was needed for the war effort. Over the next thirty years Belfast trusses were gradually eclipsed by increasingly economic steel girder construction and although a number were constructed up to the second world war – including a vast factory hall at Belfast’s Harland & Wolff’s ship building yards and in various other parts of Ireland – Russell doesn’t know of any that postdate those final mid-century examples. So not only is this an unique experiment in learning, the hall has reintroduced the Belfast Truss structure and technique after decades of languishing in obscurity.
It looks quite sophisticated, he says, compared to what the describes as the blobby bolted Frink truss, “which is not subtle.” He talks momentarily of their being a renewed interest in large span buildings, and that such sorts of truss structures could be used for supermarket and industrial buildings, competing well against steel, if steel prices continue to spiral, which, as he says, seems “quite likely”. And if this happens timber built large span could come into their own.
No-one has done the sums to compare this timberbuild’s carbon footprint to that of the originally planned, steel building, even if the total timber bill was around £40 000. Perhaps such energy and carbon footprint calculations could be integrated some of the pupil’s lessons. As it is that much again was spent on the concrete slab, during the first year, and another £30 000 on the steel used within the building. Further environmental features include a ground heat pump, natural ventilation and rockwool insulation. An aluminium roof membrane is to added soon, at about another £150, 000, a compromise of sorts, indicates organiser Crittall, the cost of working with such a small, constraining budget. Travelling hopefully, fundraising will now begin for stage three, to complete the hall. The budget ran originally to £500 000, though that has now probably risen to £750 000, also successfully raised, and the school is confident that the remaining funding can be found. Still, it’s a very economic build, about £560 sq metre. Compare this with a normal school hall and the cost would likely be in the millions. It will not have passed everyone’s attention reading this piece that I have written about another very different school hall in this issue of Green Buildings, which not only uses a very different hi tech timber system for its construction requirements, but embodies a completely different school building paradigm. I am not sure of the difference in floor space, but without wishing to make any particular judgements on the Kingsdale project, dRMM’s two halls were built to a budget of £3,4 million. The difference in cost is thought provoking. Henry Russell, talking about what kind of influence Wynstones children will have received from this experience, suggests that for every single one, it’s likely they will remember it for the rest of their lives. And also, not all, though probably many, will have found it a real and enjoyable experience. It is also one where, through physical doing, the rudiments of building and of construction will have been experienced and learnt in the body.
Kingsdale offered many other possibilities, including various second level forms of participation. As it is participatory learning has become a focus of division across the state educational sector. Those of an educational turn of mind see the Government’s Building Schools for the Future (BSF) programme as a once in a life time opportunity to integrate learning through elements of participation into the programme. Set against this are the mainstream architectural and other building sector orthodoxies who may talk the participation talk, including the right words in their tendering bids, but once awarded contracts end up ignoring such principles and resist applying their participatory rhetoric from there on in. The Sorrell Foundations JoinedUpDesignforSchools initiative has attempted to bring change to this, spearheading participation, which is good as far as it goes, but it remains to be seen how much gets integrated into BSF over the coming years. Participation, however, is not active doing, in the sense of children being in on the making of a building. Wynstones, in this small, idealistic, though equally, fun project are way ahead of where joined up thinking in schools is heading. It’s nuts to suggest that participatory timberbuild could be integrated into every inner city schools project, say, but a project like this suggests that the difficulties inhibiting active doing can be navigated. Would that it could happen more often, beyond the fearful sway of health & safety ‘litigation’ culture. And would that those in the progressive educational architectural and building sector would support it, rather than concertedly falling into line behind an educational status quo that frames participation within the conventions of the SATS target obsessed national curriculum, might venture more daring forms of participation. Not only this, but consider the prospective savings to budgets! Will it happen within BSF? It’s nice to dream but if this was mainstream education, you, I am sure, can imagine the pained looks of disbelief were such a scheme brought before the local education bureaucrats.
Both the school build and further details of its recent completion (2010) can be seen on the schools website www.wynstones.com
Notes: For the pdf of a short, technical discussion of Belfast trusses download here The Belfast roof truss, by M H Gould, et al, The Structural Engineer, vol 70, no 7, April 1992.
This piece originally appeared in Green Building magazine, Vol 17, no 2