Mothballing buildings: Proactive maintenance and conservation on a reduced budget
Tim Hutton MA MSc Vet MB MRCVS
Huw Lloyd BSc AIWC


In these days of financial stringency and a sluggish property market there are many buildings awaiting renovation or development. In this building equivalent of the ‘poverty trap’, maintenance programmes are often curtailed at the very time when reduced occupancy puts the building at a higher risk of problems such as water penetration and poor ventilation. These conditions often result in chronic problems of timber decay and especially dry rot Serpula lacrymans. In these circumstances, it can be difficult to motivate property owners and managers to carry out remedial works, as they will wish to minimise expenditure which might be made irrelevant by future developments. At the same time, it is important to prevent rampant timber decay developing; as this devalues the property, and increases the cost of eventual renovation

Examples of the conundrum discussed above can be found in every sort of property portfolio from Grade 1 listed historic buildings to offices and domestic accommodation. Similarly, the owner may be anyone from a government department to a private individual and from an occupier to an offshore based speculator. This may raise an additional problem of conflict of interest if the owner is tempted to let a listed building decay so that it can be demolished

The result of this situation is that many basically sound buildings, are allowed to decay to a stage where it is expensive or even impossible to refurbish them. In the authors opinion, this represents a negligent waste of money and valuable resources. This state of affairs is even more reprehensible because there are a few simple and cheap measures that can be taken to prevent further timber decay in such buildings. These measures should be understood and advocated by any professional involved with building conservation, so that owners can preserve their property by a policy commonly called ‘Moth Balling’ when applied to other situations.

Factors in the spiral of decay and neglect

As discussed in a previous article (1); timber decay occurs when environmental conditions in the structure become suitable for the growth of timber decay organisms. These are generally adapted to survive in the damp airless conditions found in the forest floor. This applies to both wet rot and dry rot fungi and to the wood boring insects such as woodworm and deathwatch beetle. The environmental conditions required for such organisms to flourish are very specific and narrow (9). However, the major factors are moisture levels and ventilation rates (8). These in turn are affected by many factors including building defects, maintenance programs and occupant activities.


A major problem for conservation is the difficulty in getting small maintenance tasks done in an unoccupied building or a building under reduced occupancy. This is not just a result of budget constraints but may also be due to organisational and contractual problems.


Reduced occupancy often means tenants on short term ‘licences to occupy’ or even squatters. Such people have no interest in maintaining the building so far as cleaning drains, stopping plumbing leaks or even preventing overflowing baths! Another factor resulting from such styles of occupancy is the reduced levels of structural heating and ventilation that tend to be used. In an attempt to save money, the occupiers will often use intermittent air heating systems and block all chimneys, windows and ventilators. This results in condensation problems and moisture build-up (4).

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