Conservation Technology DRYROT- A BIOLOGICALTREATMENT: BRIANRIDOUT'S NEWTHOUGHTSONA RECURRINGPROBLEM Brian Ridout is a biologist, an expert on the treatment of dry rot and timber infection, with Hutton+ Rostron, architects of Gomshall, Surrey. (Tel. 048 641 3221) Recent projects have included houses in Surrey, and more particularly, the Brighton Pavilion. The New Scientist of 19 April 1984, and the last issue of SPABNews have accounts of their work. Mr Ridout also spoke recently to conservation officers in Hampshire. His particular interest is in rationalising treatments to maximise the effect on the dry rot fungus, and to minimise the effect on the building and the people who live in it or visit it. "It is probably worth making a few points clear about dry rot. The name dry rot refers to one European and one American .fungus only amongst the multitude which destroy timber. The name gives an entirely false impression, since if the wood really is dry then the fungus is dead. Vast amounts of money are spent each year in attempts to control infestations which died out often decades before. Very few remedial firms will make this distinction even if they are aware of it. The fungus is very sensitive and, unlike wet rots, is only found in buildings although it was once reported growing. wild on a tree stump in the Himalayas. This sensitivity means that it is difficult for the fungus to become established unless conditions are exactly sµitable, and the fungus will die if environmental conditions change. Left to itself, and under ideal conditions, the fungus will destroy a building, but a careful analysis of the problems which resulted in decay can provide the solutions to the destruction of the fungus. The control of an outbreak of dry rot requires two fields of expertise. A thorough lmowledge of fungal biology, wood technology and available treatments, together with a comprehensive lmowledge of building faults and their remedy. A biologist 3 cannot control an infestation if the building still lets in water, and an architect or surveyor is liable to achieve some very unfortunate results if he tries to attack the fungus without any notion of what the fungus is capable of doing. It is for this reason that many treatment guarantees fail. The operatives are lacking in the combination of both types of skills. The solution for most architects and remedial firms is massive destruction, but this is never desirable and seldom necessary. IJ.lwopoints should be made, firstly that there is no single treatment of dry rot applicable in every case, and secondly that inappropriate or ineffective treatment can lead to a rapid spread of the fungus." Brighton Pavilion was adapted as the Prince of Wales Brighton House in 1786, and transformed in an Indian style by Nash in 1815. Dry rot was discovered in the SE corner of the. Banqueting Room and several well known remedial firms were consulted, but all claimed that the rot could not be controlled without considerable damage to the plaster. Hutton +Rostron were then consulted. The plaster was on stud work and behind it was a ventilated cavity which was inspected using fibre optics and a range of measuring devices via 12mm holes drilled through the· plaster. It was found that the movement of dry air had stopped the fungus from crossing the cavity and attacking the timbers carrying the plaster. The latter was not actually at risk provided conditions remained unchanged. The corner plaster was partially supported by a large section soft wood post which had been infected and was considerably decayed. Inspection and laboratory tests revealed, however, that the fungus was long dead. Water-mobilized fungicidal sticks were inserted into adjacent rib ends to guard against future water movement and subsequent infestation, and ventilators were built' into this and the other three corner voids to eliminate stagnant air.
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