The phrase "additional door" is correct and usable in written English.
It can be used when referring to an extra door that is being added to a structure or space.
Example: "The architect proposed an additional door to improve access to the garden area."
Alternatives: "extra door" or "supplementary door".
The main door of the fort faces north, while an additional door faces the east.
An additional door on the chapel's north side opens onto the Hibben Garden, named in recognition of John Grier Hibben's role in the chapel's construction and dedication.
On the chapel's south side are an additional door at ground level to the east and an exterior pulpit, designed after one at Magdalen College, Oxford, and named Bright Pulpit, in honor of John Bright.
Wal-Mart said there would be additional door-busters on Nov. 23.
As they walk through each door, they encounter additional doors, and so on.
"There's been some discussion of trying to use additional doors, but people have tended to stay focused on doors forward of the wing, because it's so difficult to get a structure to go around the wing," Mr. Marchi said.
Additional capacity, door-to-door service, and non-cellular methods to interact with the system would benefit groups yet to be touched by traditional ride-sharing.
To meet all of these demands, a two-room concept with an additional connecting door between the two rooms was chosen.
But she said she expected that her questions would be addressed in additional closed-door meetings.
And Saturn will soon roll out its Ion "quad coupe," which has two additional small doors to make it easier to enter or exit the backseat.
Travel boots are essential; the ramp of a Gooseneck is quite flat with not a steep slope, mainly due to the back also having an additional swing-open door.
