A virulent dry rot attack had developed in the NW light well. The decision was taken, unknown to Hutton+Rostron, to remove the cracked and saturated rendering from all four light wells. This provoked a stress reaction within the fungus in the NWwall and it grew rapidly and fruited in an adjacent venti la ti on shaft. The fruiting body was removed and the wall sterilized. The fungus then began to fruit on the walls of the light well itself. These sporaphores were allowed to grow and then removed before they produced spores. The fungus was thus wasting its resources by fruiting in a place which was accessible and w~ere it could be regularly cropped. If the walls had been sterilized it would probably have fruited at a lower level behind the plaster. The wall below this outbreak is totally inaccessible, on one side there is the internal plastering of the Music Room on the other side there is Regency wallpape~ The problem is how to stop the rot travelling down the wall and destroying both decorative finishes. 'i'he solution chosen was to roof over the light well and to install a dehumidifier. This.will remove moisture from the walls and create a pattern of of' water movement which should halt the downward spread of the fungus. A band of water-mobilized fungicidal paste will be inserted into the walls at the lowest possible level within the light well. This will form a barrier which will stop fungus in the wall from reaching a food source at a later date, and halt any transport of water by the fungus below the fungicidal band . .Any dry rot treatment is only as good as the future maintenance. If it is poor then the rot will probably return even if the ''full dry rot treatment" of the remedial firms has been used. 'i'he sol- ~tion to this problem at Brighton will be the installation of remote sensors at points of high risk. These will measure timber moisture content, temperatures and humidity and will give a warning if conditions change Brian Ridout/ Mike Pearce 4 HISTORICTIMBERFRAMINGVERSUS THERMALINSULATION I am sure that most members who have been looking at timber framed buildings over a number of years will have seen examples where the renovation of external walls, including new thermal insulation, vapour barrier, etc., has resulted in the deterioration of the timber frame. The root of the problem seems to be condensation within the thickness of the wall. This is usually only revealed in cases so bad that dampness becomes apparent inside the building. Then it is not uncommon to find, on stripping off the internal lining, that the frame is saturated. My colleagues and I are not aware of any research that has been carried out on this specific problem, nor do we know how widespread these effects are. Can I therefore ask AGO members to let me know what experience they have of such problems together with practical solutions? I am hoping that if we can collect enough evidence, we may.be able to persuade a suitable institution to research both the extent of the problem and ways of overcoming it whilst still achieving a decent level of thermal insulation. Peter Richards Finance VAT: WORKSTOLISTEDBUILDINGS Some will consider much has been achieved persuading the Treasury to zero-rate VATon alterations and extensions to l\sted Bu~ldings. Ot~ers will see it as only saving the regimental colours in retreat, The key area of concern should be that of repair or maintenance. How many times does a Conservation
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