Patent attributes
Fenestration unit monitoring devices described herein are configured to retrofit an existing fenestration unit lock assembly to incorporate components that are capable of monitoring the locked or unlocked status of the existing fenestration unit lock assembly and/or the panel position status of a movable panel of the fenestration unit. The fenestration unit monitoring devices include a monitor housing configured for mounting on the surface of a frame member on which a fenestration unit lock assembly is already mounted. The monitor housing of the fenestration unit monitoring device includes a lock cavity such that a portion of the fenestration unit lock assembly is located in the lock cavity formed between the monitor housing and the surface of a frame member to which the monitor housing is mounted.