Egress window size and dimensions first lets look at the minimum opening area required.
Roof egress requirements.
The minimum egress window opening height is 24 high.
The top rails of a guardrail system must be 39 to 45 inches above the walking working surface 29 cfr 1926 502 b 1.
Minimum 5 7 square feet of net clear opening area.
For example all means of egress shall have a ceiling height of not less than 7 feet 2134 mm the building code then lists six possible exceptions to that one stipulation.
Operation and maintenance requirements for exit routes.
Nfpa emergency exit door requirements for locks.
1 each exit route must be maintained to minimize danger to employees during an emergency.
This includes compliance with all of the following.
In summary free access to the roof from the stairwell is not required by the ibc or nfpa 101 but may be required or preferred by the local code official.
Free egress from the roof to the stairwell is required for occupied roofs but is not mandated by the ibc or nfpa 101 for unoccupied roofs.
Whether you re in a historical zone or not all means of egress must comply with highly specific thorough detailed building codes.
The egress window must have a glass area of not less than 8 of the total floor area of room s for which it is servicing to allow the minimum amount of sufficient natural light.
The egress from the space must be sized for the roof occupant load and must be continuous to the exit discharge at grade.
The net clear opening area net clear height opening and net clear width opening.
The minimum egress window opening is 20 wide.
A single exit or access to a single exit shall be permitted from any story or occupied roof where one of the following conditions exists.
2 each exit route must be free of explosive or highly flammable furnishings and decorations.
The means of egress serves a room with an occupant load above 50 people the means of egress is used in an exit enclosure or while serving a high hazard area while swinging the door should leave available at least half of the required width of a corridor hallway etc for use.
Two exits are required for occupancies up to 500 persons.
A the danger to employees must be minimized.
Intermediate structural members for example midrails or screens must be installed when there is no wall or parapet wall at least 21 inches high 29 cfr 1926 502 b 2.