Facilities are structures built in a base to provide additional benefits to the survivors. Each base has a fixed number of interior and exterior facilities that can be built with a fixed number of pre-built facilities already in place. When the max number of facilities is reach, the only way to built a new facility is by deconstructing another; must be a non pre-built one.
Construction & Upgrading
In order to construct a new facility you will need an empty slot, marked by a blue square, and the required construction cost. Construction takes time, with certain abilities shortening this time, and this should be taken into account when selecting the facility.
Once a facility is constructed it can be upgraded. Upgrading costs more materials and time, but usually requires the acquisition of special resources. If an upgrade requires a special resource, the construction will be halted and the map will be marked with the resources location.