Ratings of opening in exit enclosures

[mtCDCcb]

We have a exterior wall with openings in an exit enclosure that is within 10' of an adjacent non rated exterior wall. The exit enclosure itself is >30 from the property line. Due to this scenario we are requiring the exterior wall to have an hour rating with 45 minute rated openings (1022.6 2009 IBC). The applicant is proposing to assemble the adjacent wall with a one hour rating so the exterior walls and openings can be non rated. In your opinion is this acceptable? Thanks.

[Jerry Peck - Codeman]

[mtCDCcb]

They are taking an exterior wall (wall 1) that is not required to be rated and turning it into an hour rated wall. There is another exterior wall (wall 2) that is within 10' of this wall (1) that is not rated which has windows. If wall 1 met the minimum requirements (non rated) it would require wall 2 and its openings to be fire rated. To get around this the applicant is proposing to rate wall 1 (1 hour) in order to not have to rate wall 2 and its openings. Is this acceptable.

[Jerry Peck - Codeman]

If the exit enclosure's exterior walls meets this: (bold and underlining are mine)
- 705.5 Fire-resistance ratings. Exterior walls shall be fire-resistance rated in accordance with Tables 601 and 602 and this section. The required fire-resistance rating of exterior walls with a fire separation distance of greater than 10 feet (3048 mm) shall be rated for exposure to fire from the inside. The required fire-resistance rating of exterior walls with a fire separation distance of less than or equal to 10 feet (3048 mm) shall be rated for exposure to fire from both sides.

Then the exit enclosure's exterior walls should be good as they would meet the code's requirements for fire-resistance rating based on the Type of Construction and Occupancy as required and shown in Table 601 and Table 602.