Length
The length of a basement bulkhead refers to how far the opening extends from the side of the home. This dimension depends on the basement's depth and the angle of the stairway that leads from the basement door to the bulkhead. For example, an 8-foot basement with stairs that rise at a steep 45-degree angle has an 8-foot bulkhead length. Stairs with a less steep slope create a longer bulkhead opening.
Width
A bulkhead's width depends on the width of the basement stairs. The opening may be wider than the basement door or cut to match the width of the door frame. A relatively standard width for bulkheads is 4 1/2 feet because it allows room for someone to carry large objects up from and down to the basement. It is also large enough for someone to escape to or from the basement with ease in the event of an emergency.
Doors
Most bulkheads, regardless of length and width, feature a pair of overlapping doors that open outward. Large doors provide a larger opening than smaller doors, but they are heavier and more difficult to open than smaller doors. Bulkhead door manufacturers produce bulkhead doors that slope at different angles. The angle doesn't affect how the doors operate or the size of the bulkhead opening that they conceal.
Considerations
Bulkhead door manufacturers offer extensions that expand the size of standard bulkhead doors. Therefore, it is much easier to order doors to fit an existing bulkhead than to enlarge or partially fill in a basement stairway. If you install a bulkhead and basement stairway for the first time, consult your location's building codes, which may specify minimum allowable door dimensions and stair angles.