Dawn Hoff wrote: I frankly think that the reason the roof fell down is that it hasn't been maintained for 30 years.
or using simple "botanical" agents, such as olive oil, tung oil, or beeswax. It isn't going to happen or work, period. It simply will NOT have an effect on these little fellows. You must have an intimate relationship and knowledge of the their biology to be even slightly successful in their control or eradication from wood. I would further point out that Hymenoptera control is very challenging for even us professionals and requires due diligence by the property owner. Most are harmless in your region of Spain as far as the timber frame structure is concerned, other that European Carpenter Bees (Xylocopa ssp) that will require some maintenance work with keeping them at bay, and the wood rendered with treatment and/or proper oils.
"with a net in front of the opening between upper and lower roof."
The wood between the upper and lower roof is heat treated
Jay C. White Cloud wrote:
Burra, there are traditional wood (timber frame) roofs throughout Europe, (including Spain and Portugal) that are over 500 years olds (some over 1000 years.) Maybe new homes need there wood roof timbers and beam work replaced every twenty years but traditionally built roofs do not. Perhaps you meant the roof covering, but even then a tile or stone roof should last a minimum of 300 years or longer.