Smoke detector requirement in Saarland – a test by Stiftung Warentest is relevant here

Children's room : Smoke detectors are mandatory in all existing children's rooms.

Living room : A smoke detector is only required in the living room if it is also used as a bedroom or as an escape route, i.e., if it must be crossed to leave the apartment.

Corridors : Smoke detectors are mandatory in all corridors that serve as escape routes.

Other rooms : The same rules apply here as for living rooms.

More and more German states are introducing mandatory smoke detectors – but a recent test by Stiftung Warentest shows that price isn't the only factor to consider when choosing the right device. The most expensive smoke detector tested, at €103, remained silent even in thick smoke.

How quickly do the devices warn of smoke, and how prone are they to false alarms? Seven out of 14 smoke detectors were rated "good" by Stiftung Warentest, and the test winner costs a comparatively modest €26.50.

Those looking for good smoke detectors for individual rooms can find them for as little as €20, according to the test results. Networked smoke detectors, which communicate wirelessly and thus intelligently monitor larger houses and apartments, cost a bit more, but even in this category, two systems proved their worth for €65 and €94.

To avoid frequent battery changes, Stiftung Warentest advises against cheap devices with alkaline batteries. The lithium batteries in the slightly more expensive smoke detectors promise a lifespan of at least ten years.

The detailed test can be found in the January issue of the magazine "test" or can be accessed online