We are constantly being bombarded with valuation surveys that demand a property is 'Timber Treatment Needed' or "You must get a PCA registered timber and damp surveyor to do a timber treatment report'.
There are some notes on the subject here: Why Should You Treat Timber?
The bottom line is that timber should NOT be treated. There is simply no justification for treating timber. The best way to stop any form of problem - rot, beetle attack - is to dry the timber out. We've already covered the subject of BS7913 elsewhere in this site - but the new British Standard in Historic Building Conservation clearly states that timber treatment is unneccessary and should only be used as a last resort.
The solution to the issue is actually very simple - to educate building surveyors. RICS has yet to issue clear guidance on the subject, and I urge them to do this in a clear and unambiguous way. BS7913 sets out the parameters - surveyors just need to learn, and take on board. Then we wouldn't carry on seeing these ridiculous requirements from building societies and banks to 'Treat all timbers' and surround yourself with toxic chemicals. The only winners at the moment are the chemical companies.
One of the leading experts in the world on timber problems - Brian Ridout - who writes in the English Heritage book - Timber Decay in Buildings - says that timber treatment is never needed. Every chapter discusses problems - either rotting, or insect attack - and in every chapter the recommended solution is to first dry the timber.
Our advice: Do not allow anyone from the Property Care Association spray toxic chemicals in your home. They are not needed. If the timber is dry, it will not need any form of treatment. If wet, then dry it out and the problem will go away.