Eight out of ten fire-related fatalities occur in dwellings. It is a fact that smoke detectors save lives, which emphasizes the importance of every home having a functioning smoke detector. In Norway, smoke detectors in dwellings are mandatory, and recommendations on which detector technology to use and the position of the detectors are given. Smoke detectors should be installed on the ceiling, outside of dead-air space (close to walls). In this study, ten smouldering fire experiments have been conducted to: • investigate if smoke detectors with CO sensing can alert residents at an earlier stage than photoelectric smoke detectors, consequently increasing chances of egress and survival for a sleeping person. • measure concentrations of toxic gases in a room where a smouldering fire occurs and investigate if tenability limits are exceeded when n photoelectric smoke detector is activated. • investigate if smoke detectors placed within dead-air space are activated at a later stage than smoke detectors placed according to the recommendations.