Material matters in conservation more durable than any modern equivalents - the principal reason being that it was logged from 200 year old trees. Current practice (in some instances) is to fell after as little as 45 years and in doing so to try to bolster the durability of the material by the introduction of chemicals. The effect of this was illustrated by the use of diagrams which graphically emphasised the difference between the structure of young and old trees. The key lies in the way in which growth rings change from being juvenile sapwood to becoming mature heartwood in later life. In order to achieve this they undergo a move from juvenile sapwood to mature sapwood then through juvenile heartwood to mature heartwood. As far as decay is concerned, it is the juvenile sapwood that it important for this is what conveys the nutrients to the leaves and hence contains the living materials. It is these on which the organisms of decay thrive and hence the sapwood is what they attack. However, they cannot do this in the wild and hence only do so once a tree has been felled. Furthermore, the durability of the timber only begins as the fibres of the timber change with age. In juvenile wood, fibres lie horizontally and have little durability but in mature wood the fibres are at a much more acute angle and have strength in compression. This process relates to the cycle of change from sapwood to heartwood and timber has no durability until heartwood is formed - typically say after 35 years. If trees are felled at 60 years (the current norm) they may only contain 15 years of juvenile and 30 years of mature hardwood. Compare this with the former practice of felling a tree after 200 years which would contain 15 years of juvenile and 170 years of mature heartwood! So the younger trees now being felled contain less, latewood, have lower density and lower strength and are more prone to longitudinal shrinkage. These problems are compounded by other changes in practice. The strength of timber is governed by the spacing of the growth rings - the closer the better. Wild grown timber has this quality but commercially grown ex10 hibits wider rings which have less strength. In addition the manner in which timber is cut in the yard has changed so specifying timber may not give the durability required. Brian closed his talk with more cautiona1y notes. Nondurable timber is more prone to attack- it may contain chemicals but this alone is not sufficient to sustain contact with damp conditions and hence it needs to be kept away from direct contact with moisture, since fungal attack is restricted to zones of moisture. Woodworm only attacks sapwood - so future problems are potentially being stacked up. RichardMorrice Richard started with quite a brave opening gambit given the nature of his audience: he was first employed in Architectural Salvage which entailed knocking down quite a few farms! He did, however, point out that to do this properly requires an understanding of how they were built in the first place, and this gave a very convenient lead into his current calling as an historic building consultant which involves the same thing but on the other side of the fence. This understanding is crucial to the success of a scheme - in his words "you can't maintain a Mercedes Benz with a Skoda mechanic"! The historic building consultant is thus a key part of the decision making team in that his or her role is to analyse the building, inform structural decisions, and inform and add to the research or wider body of knowledge. Common to all timber-framed buildings is their simplicity-in fact he could hardly have expounded his philosophy in more simple terms. Basically, you have a tree; you cut it up - you build a building. As a result, this type of building exhibits a common characteristic of being easy to understand - almost as easy in fact as Richard's next strand of philosophy that all timber-frame buildings have a basic logic to them - namely: "it must stand upright - if it falls it's a plank". Inevitably, of course, it's not quite that simple - if it was, why would you need a consultant? The answer lies in the consultant's specialist knowledge - the understanding that he or she can bring to the component parts to inform the decision making process. Consultants look for the frames, which must be put together and the joints are crucial to this. The relationships between the various members are usually simple with the carpenter's marks being the key to the construction. New St Chad's by George Stuart. These follow a logical and sensible format albeit sometimes tinged with particular local variations and styles. If these various parts are tabulated they can provide a coherent picture of what is there and also what is missing, thus giving a clue to the building's original form. The frame needed to be filled (it stopped the draughts!), and wattle and daub was the most commonly used infill. Evidence of this is found in stave holes and wattle grooves but there are many variations, such as planks, lath and plaster or even alabaster slips. The end result of this looking for clues/ logic/patterns is an informed analysis of how the building has developed. This is then a vital element of a team decision which involves the historic buildings consultant, the architect and the Conservation Officer. Many of us have seen the role of such consultants and, as a result of the lessons learned, would echo his closing remarks that this input is not an additional oncost, nor an unnecessary luxury, but very much an essential part of a multidisciplina1y approach to the problems that we all strive to solve. Brucelnduni Nobody puts a message across quite like Mr Induni. The image is unmistakable, the style inimitable and as a result of this people tend to remember not only what he says but how he says it. His opening gambit was to inform us that he was diametrically opposed to the previous speaker - quite a statement for someone who is essentially in the same game. This was followed by an unforgettable allusion to Botticelli's Context 59 September 1998
RkJQdWJsaXNoZXIy MjgyMjA=