exit stair

[hans@dha-architects.]

I'm designing a new three-story apartment building of VB construction; the stair towers are essentially on either side of the building, so three of the four stairwell walls are exterior walls. The wall that separates the stair from the interior of the building is 1 hour rated, do the three exterior walls of the stair or any portion of building exterior wall adjacent to the stair require a rating? The building is not near another building or lot line so no separation is required for that reason, as far as I can tell the exterior walls would not require a rating, or am I reading the code incorrectly?

 

[steveray]

Any windows or other exterior walls <180 degrees from the stairwell?

1023.7 Interior exit stairway and ramp exterior walls.
Exterior walls of the interior exit stairway or ramp shall
comply with the requirements of Section 705 for exterior
walls. Where nonrated walls or unprotected openings
enclose the exterior of the stairway or ramps 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 ramp, or to the roof line, whichever is lower.

And welcome Hans, good to see some more CT designers on here...

 

[hans@dha-architects.]

the building wall is straight (60' or so) and the stair is approx. in the middle, long side of the stair tower is on the building wall, there is a window on the short wall of the stair tower, which would be perpendicular to the building, and there are windows on the building wall about 4' from the tower on either side.....I wish I could just insert snapshot of the plan, but hopefully that makes sense.

on another note, have you seen the new energy code for our region! R-60 in attics, R-30 walls?!!

 

[steveray]

on another note, have you seen the new energy code for our region! R-60 in attics, R-30 walls?!!

You can still use R49 (raised heel trusses) if you can maintain it to the exterior sheathing... and you can get out of 30 with continuous foam somewhere......

N1102.2.1 (R402.2.1) Ceilings with attic spaces.
Section N1102.1.3 requires R-49 insulation in the ceiling
or attic, installing R-38 insulation over 100 percent of the
ceiling or attic area requiring insulation shall satisfy the
requirement for R-49 insulation wherever the full height
of uncompressed R-38 insulation extends over the wall
top plate at the eaves. Where Section N1102.1.2 requires
R-60 insulation in the ceiling, installing R-49 over 100
percent of the ceiling area requiring insulation shall
satisfy the requirement for R-60 insulation wherever the
full height of uncompressed R-49 insulation extends over
the wall top plate at the eaves. This reduction shall not
apply to the insulation and fenestration criteria in Section
N1102.1.2 and the Total UA alternative in Section
N1102.1.5.

If you are paying member you can post stuff or I think you can post a link.....I have just payed for the past 10 years or so for the value I have gotten from this forum...

 

[Tim Mailloux]

You can still use R49 (raised heel trusses) if you can maintain it to the exterior sheathing... and you can get out of 30 with continuous foam somewhere......

.

Throw some Zip R sheathing on the exterior to meet the continuous insulation requirement while also giving you a good nail base for any exterior finishes.

 

[steveray]

For $90 a sheet and increase the heck out of your shear nailing.....But yes, that requires the builder to adapt less....

 

[hans@dha-architects.]

I didn’t mean to hijack my own thread about insulation, my partner was just browsing thru the new code online and told me the updates, anyway, only question here is about the rated walls

 

[steveray]

Tough to do without a sketch, but if another part of the building is a threat to the exit you rate the exterior wall and openings, VA makes the wall go away, but not the openings....

In other words, when the fire burns out of the unrated exterior wall, does it light the exit enclosure on fire?

 

[hans@dha-architects.]

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I IIIIIIII I
I IIIIIIII I

how do you like my sketch above?! so the building wall is the long straight line and that's the stair configuration below it, the main wall has a window about 4' away from the stairwell on either side and there are windows on either end of the stairwell as well, so after reading 1023.7 for the 20th time, I would agree with you, the main wall would need a 1 hour rating for 10' on either side of the stairwell, the windows would need 3/4 hour protectives (fire shuttters?) or simply remove them (they're really just bonus windows for the corner units), but the three exterior walls of the stairwell would not need to be rated and the windows could remain - is that how you would interpret that?

 

[hans@dha-architects.]

____ _______________________ ________
I IIIIIIII I
I IIIIIIII I

how do you like my sketch above?! so the building wall is the long straight line and that's the stair configuration below it, the main wall has a window about 4' away from the stairwell on either side and there are windows on either end of the stairwell as well, so after reading 1023.7 for the 20th time, I would agree with you, the main wall would need a 1 hour rating for 10' on either side of the stairwell, the windows would need 3/4 hour protectives (fire shuttters?) or simply remove them (they're really just bonus windows for the corner units), but the three exterior walls of the stairwell would not need to be rated and the windows could remain - is that how you would interpret that?

shoot, my sketch got shifted when i posted it, the stair should be in the middle of that long line and those little spaces are windows

 

[steveray]

That's fine...

Where nonrated walls or unprotected openings
enclose the exterior of the stairway or ramps 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.


So if the stair is a "centered appendage"on the exterior wall, you need to rate the exterior walls and openings within 10'....Likely in your VB building you can get a 1hour exterior already and then you are just looking at openings....

If that makes sense...

 

[hans@dha-architects.]

That's fine...

Where nonrated walls or unprotected openings
enclose the exterior of the stairway or ramps 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.


So if the stair is a "centered appendage"on the exterior wall, you need to rate the exterior walls and openings within 10'....Likely in your VB building you can get a 1hour exterior already and then you are just looking at openings....

If that makes sense...

yes, so I'll do non-com plywood or Nocom sheathing for 10' on either side of the stair to 10' above highest landing and probably just eliminate the windows on the wall..........it's either that, or rate the entire stairwell and openings (or eliminate opening) and don't rate the building wall, but I think I'd rather have the windows in the stair and do the former

 

[Paul Sweet]

You would only have to rate the walls at the ends of the stairs (perpendicular to the main wall) to keep the unprotected windows in the main wall. The outside stair wall (parallel to the main wall) can be unrated and have windows.

 

[hans@dha-architects.]

You would only have to rate the walls at the ends of the stairs (perpendicular to the main wall) to keep the unprotected windows in the main wall. The outside stair wall (parallel to the main wall) can be unrated and have windows.

that is an option, but to keep the windows in those rated walls, they'd need 3/4 hour protectives I assume, i.e. fireshutters or something? I think we decided to rate the building wall, we're eliminating one set of windows and shifting the other windows beyond the 10' rated section. I'd prefer to have the stair windows where they are at the landings as opposed to on the long wall

 

[steveray]

Something like this would get you close but you would have to spend some time in the UL wizard to find an assembly you want to meet...