AskCodeMan

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.

mtCDCcb wrote: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).

That is what the code requires, yes.
- 1022.6 Exit enclosure exterior walls. Exterior walls of an exit enclosure shall comply with the requirements of Section 705 for exterior walls. Where nonrated walls or unprotected openings enclose the exterior of the stairway and the walls or openings are exposed by other parts of the building at an angle of less than 180 degrees (3.14 rad), the building exterior walls within 10 feet (3048 mm) horizontally of a nonrated wall or unprotected opening shall have a fire-resistance rating of not less than 1 hour. Openings within such exterior walls shall be protected by opening protectives having a fire protection rating of not less than 3/4 hour. This construction shall extend vertically from the ground to a point 10 feet (3048 mm) above the topmost landing of the stairway or to the roof line, whichever is lower.

The applicant is proposing to assemble the adjacent wall with a one hour rating so the exterior walls and openings can be non rated.

I am not able to envision what he is doing, unless he is making that exterior wall such that it does not have any openings in it ... but you said he was going to make it so the openings can be non-rated, which means there are openings ... so I am missing something.

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.

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.