Can a bonus room outside of a unit still appraise with the unit?

[Kat He]

My primary residence is a second floor 2bd/2ba unit and directly across from it (on the other side of the staircase landing), is a 10x13 bonus room with two windows and a closet. I haven't measured the windows to see if they fulfill the 'room' requirements, but if I fulfilled all the other reqs by adding a wall mounted HVAC system and a smoke detector, could it appraise as an extra bedroom along with the unit? I am unsure how a detached/bonus room would be treated in an appraisal in this case. Thanks in advance for any input!