service entrance

i believe it is legal, yes, but your building may have an issue with it. Assuming they would require you to leave the door in place, it could be a big hazard for a fireman who would might try to knock the door open but wouldn't be able to.

I'm sure it depends on what and where the other fire exits are. This doesn't sound like something you could do without DOB approval, given that it's a change in egress.

I've seen people cover up the door to some extent, but you do want to keep it accessible in case of an emergency. Plus, you need two points of egress.

MrRussell - just curious - why do you need two points of egress. Many apartments, if not most, have only one. Sometimes the second, service door, is right next to the main door, so egress would not really be the issue.
Perhaps the accessibility to a second door is more for the occupants' feelings of safety than by code?
Anybody have any written DOB codes on this issue?

One door is OK, but it needs to be within x feet of two separate stairways. The code used to be more rigorous, as in some 1920s buildings. Miette is correct that "change in use, occupancy or egress" requires DoB approval.

At some period (not now) the two-stairway rule didn't apply if only one apartment per floor. E.g., the towers in the Majestic, Eldorado, Beresford.

Usually apartments with just one door have two accessible interior stairways (as NWT states) -- or, just as often, a fire escape. Who wants to live in a place with only one path out?

Here's the original Devonshire House plan, with seven sets of stairs for only 11 apartments per floor: http://www.columbia.edu/cgi-bin/dlo?obj=ldpd_YR_0015_MH_001_004&size=large

Or one of the Eastgate buildings, with three sets of stairs and two fire escapes for eight apartments per floor: http://www.columbia.edu/cgi-bin/dlo?obj=ldpd_YR_0428_MH_001_001&size=large

NWT - Those original floorplans are very interesing (aside from the fact that the original layouts were not very "grand"). Am I reading them right or were some of the exit stairs INSIDE several of the apartments? And those do not seem to have access to a second staircase, because of the interior garden?

nwt - question was about Deveonshire House, but same actually goes for that third staircase in Eastgate.