Windows Allowed in Exit Stairway?

[fj80]

Are windows allowed in the exterior wall of an interior exit stairway? Stairway walls are rated 2 hours. The window would be located in a stair wall that is set back 23' from the front property line, so wondering if the window is allowed and if set back this far from the property line, if it could also be non-fire-rated? Location is Washington DC, code is IBC 2012. If the window is required to be fire-rated, what is the fire rating requirement and what is the maximum size the window can be? If you can direct me to specific sections of the code that would be great. Thanks.

 

[mark handler]

1023.4 ibc

 

[RLGA]

The exterior walls of an interior exit stairway are not required to have a fire-resistance rating unless the walls are required to have a rating based on type of construction per Table 601 (for exterior bearing walls) or based on fire separation distance per Table 602. Unprotected openings are permitted in the exterior walls of the interior exit stairway per Table 705.8. If exterior openings are required to be protected (excludes doors to the exit discharge), then windows would not be permitted unless they have been tested in accordance with ASTM E 119 or UL 263 and have a rating equal to or greater than what is required for the walls.

 

[fj80]

Thank you very much. This is very helpful. Follow-up question- we would like to add windows to the existing 2nd floor side wall of the building, but the wall is right on the property line. Per Table 705.8 I believe windows are not allowed in this location because the fire separation distance is 0. Is this correct?

 

[fj80]

Also, just to clarify- since my exit stairways are required to be 2hr rated per 1022.2, wouldn't that mean that all four walls of the stairwell have to be rated? Or is it only the interior walls of the stairwell that have to be rated? (My exit stairwells both sit at the exterior corners of the building, so they have two interior walls and two exterior walls.)

 

[RLGA]

Thank you very much. This is very helpful. Follow-up question- we would like to add windows to the existing 2nd floor side wall of the building' date=' but the wall is right on the property line. Per Table 705.8 I believe windows are not allowed in this location because the fire separation distance is 0. Is this correct?[/quote']​That is correct. Per IBC Table 705.8, any type of opening is not permitted when the fire separation distance is less than 3 feet, and unprotected openings are not permitted less than 5 feet when the building is not sprinklered.

 

[RLGA]

Also' date=' just to clarify- since my exit stairways are required to be 2hr rated per 1022.2, wouldn't that mean that all four walls of the stairwell have to be rated? Or is it only the interior walls of the stairwell that have to be rated? (My exit stairwells both sit at the exterior corners of the building, so they have two interior walls and two exterior walls.)[/quote'] IBC Section 1022.7 addresses exterior walls of interior exit stairways and do not require them to be rated except per IBC Section 705, which points you back to Sections 601 and 602 for fire-resistance ratings (See Section 705.5).

 

[ADAguy]

RLGA, is my understanding incorrect that a stairwell on a property line could in fact be all rated glass if the glass is 2hr or as required by code? This assumes fixed glass.

 

[fj80]

Thank you! This has been very helpful.

 

[RLGA]

RLGA' date=' is my understanding incorrect that a stairwell on a property line could in fact be all rated glass if the glass is 2hr or as required by code? This assumes fixed glass. [/quote'] ​Technically, yes, if the glazing assembly (i.e., frame and glass) is tested per ASTM E 119 or UL 263. These are the same standards that solid walls are required to be tested under. So if a solid wall has been tested for the required rating, why wouldn't a "transparent" wall be permitted if it was tested using the identical methods for the same (or higher) rating? Further, the glazing assemblies are tested from both directions, which is required for exterior walls that are within 5 feet of the lot line.

There is, of course, some logical problems, such as, why pay the high price for a "transparent" wall when your neighbor can build a solid wall right up against it in the future? Then, there is the preconceived notion that glazing, regardless of its fire-resistance performance, is still an "opening."

 

[RLGA]

As an example of the "preconceived notion" I mentioned above, I had a client who had property adjacent to a wilderness preserve. The lot line was essentially at a steep slope downward. My client wanted to build right up to the lot line and use a glazing system that has been tested per ASTM E 119 (he apparently had the money). This seemed logical, since the adjacent property was a wilderness preserve and the terrain at the lot line would have virtually made it impossible to build on even if there was a chance they would build on the preserve.

We thought we had a solid case...wrong! The building official just could not comprehend that a glazing system such as this would not be considered an "opening."

 

[ADAguy]

Interesting comment by official, There is a difference between open and transparent, transparent should resist rain and wind while allowing visability, duh?

 

[kilitact]

Good catch by the building official.

 

[steveray]

If it is listed and tested as part of the wall (or all of it) I believe it is good as RG spoke of. There is a difference between a glass wall and an opening. The opening gets assumed to be left open at some point. The wall, not so much. Glass walls are hard to open, not as hard as brick doors, but you know what I mean....