Top and bottom surface bolts are used on the inactive leaf of pairs of doors. The bolts hold the door closed until the full door opening is require. For office suite entry doors, the need is usually during move-in to get furniture through the door. But the full opening may be required for equipment replacement, maintenance, and other routine purposes.
When specifying surface bolts or any hardware device, keep in mind the height of the installation for each door opening. This door is 3 x 9 feet. The top bolt is less than 12 inches long and requires a key to unlock the bolt. The only way for most people to operate the top bolt is to stand on a ladder.
The door is inconvenient, although not impossible, to use. Just store the ladder in the lobby coat closet for those times the full opening is needed.
An alternative solution will improve the user operations and safety. Use an automatic top bolt with a manual bottom bolt. This arrangement provides top and bottom latching when the active leaf is closed. And it keeps employees and maintenance staff safely on the floor. The inactive leaf can be opened without a ladder, simply by retracting the manual bottom bolt.