Insect repellents such as ProtoxInsekt are generally approved for use in use class 1 according to DS/EN 335-1. This means indoors, where there is no risk of direct wetting or re-wetting due to condensation (if this is the case, we have a use class 2 or 3 situation).
There are some situations where a use class 1 situation becomes a use class 2 situation, such as a burst pipe under a floor or condensation due to blocked or missing ventilation. When the burst pipe is repaired or ventilation is re-established, the structure becomes dry and we again have a use class 1 situation where Protox Insect can be used.
Products like ProtoxInsekt should only be used by professionals, as they are deemed to have the expertise to determine which use class the situation belongs to.