I only have 2 reasons to put a door back. 1 is to keep the heat from moving upstairs and making it too hot up stairs. 2 a door will act as a firebreak should that happen. Just my thought.
Hmmm, that’s a safety perspective I didn’t consider. I’ve lived in my current house 40+ years and the upstairs steps are exposed, so fire has never been a thought. It does stay warmer upstairs, but my HVAC company has told me the ducts they are running and my insulation guy said the insulation he wants to install should control the upstairs temps.
by 
I only have 2 reasons to put a door back. 1 is to keep the heat from moving upstairs and making it too hot up stairs. 2 a door will act as a firebreak should that happen. Just my thought.
Hmmm, that’s a safety perspective I didn’t consider. I’ve lived in my current house 40+ years and the upstairs steps are exposed, so fire has never been a thought. It does stay warmer upstairs, but my HVAC company has told me the ducts they are running and my insulation guy said the insulation he wants to install should control the upstairs temps.