In a building, whether residential or public, the most common and easiest way to break in is by breaking through windows and doors. When burglary protection is not used, in the production of joinery, thieves need little time and effort.
According to a pan-European standard, there are six types of burglary resistance classes – RC1, RC2, RC3, RC4, RC5 or RC6. They are also found as WK1, WK2, WK3, WK4, WK5 and WK6. The classification is based on experiments with static and dynamic loads on components (windows, doors and suspended facades), as well as on the basis of simulated theft attempts, which compare the time and tools needed by the thief to overcome the obstacle.