Is it legal to have surveillance cameras at home?

[cousin.it.addams@xxxxxxxxx]

I am a tenant who has suffered repeatedly from petty thefts that have
taken place over the last 3 weeks.

My landlady wants to install surveillance cameras with video and audio
in the common area (excluding the bathroom) but is apprehensive that
the other tenants will complain about invasions of their privacy and
possibly take legal action against her.

I would appreciate it if someone could give me some insight into laws
on surveillance cameras in the state of Washington.

I am posting on behalf of her as she is not net savvy.

PS - Common area does not include rented rooms.