Grill in a 20 minute rated door?

[Robert]

Hello all. I'm working on an existing interior tenant space in which the building is Type 5A 1 hour construction. The existing restroom door has a grill near the bottom (since there is a return air duct in the bathroom). I am replacing the door. The door is in a corridor which requires fire partitions and per Table 716.5 requires the door to be 20 minute rated. That said, is there an exception for grills in a rated door? If not...relocate return air grill from inside the bathroom to the 1 hour rated corridor ceiling or wall? If I do that, is there a fire damper that needs to be installed in the duct? New territory for me...thanks.

 

[cda]

What code and edition are you under.

I believe the answer is no grill allowed

 

[cda]

http://idighardware.com/2009/08/louvers-in-fire-rated-doors/

 

[Robert]

I'm under the 2016 CBC. Original permit drawings from the 80's show a louvered door...maybe they allowed them back then, or I'm incorrect in my interpretation of corridor fire partitions and doors.

 

[cda]

Yes long time ago they were allowed

 

[mtlogcabin]

Some of the older legacy codes allowed the corridor fire partitions to wrap around the restrooms which would then place the restroom within the rated corridor and no doors where required at all.
I can not recall if a return air was ever allowed in a restroom at all. I believe it should be exhaust only not return air

 

[Robert]

Some of the older legacy codes allowed the corridor fire partitions to wrap around the restrooms which would then place the restroom within the rated corridor and no doors where required at all.
I can not recall if a return air was ever allowed in a restroom at all. I believe it should be exhaust only not return air

Yes, it's odd having return air in there. Out of curiosity, since the building is rated as 1 hour construction throughout because of the size, wouldn't that make all of the rooms (including the bathrooms) the same as the corridor with respect to being 1 hour?

 

[cda]

Yes, it's odd having return air in there. Out of curiosity, since the building is rated as 1 hour construction throughout because of the size, wouldn't that make all of the rooms (including the bathrooms) the same as the corridor with respect to being 1 hour?

Normally just the corridor walls are rated walls, not the interior classroom walls, except the common one with the corridor.


What mt is saying sometimes the rating goes into the room, so in that case the door does not have to be rated

 

[Robert]

Normally just the corridor walls are rated walls, not the interior classroom walls, except the common one with the corridor.


What mt is saying sometimes the rating goes into the room, so in that case the door does not have to be rated

Thanks, then the grill in those cases could work. I thought in a 1 hour rated structure that all of the walls need to be rated, not just the corridor walls or separation walls. Please shed some light as I'm presently calling all new construction (even the closet and bathroom walls and non-bearing partitions) to be 1 hour.

 

[cda]

Thanks, then the grill in those cases could work. I thought in a 1 hour rated structure that all of the walls need to be rated, not just the corridor walls or separation walls. Please shed some light as I'm presently calling all new construction (even the closet and bathroom walls and non-bearing partitions) to be 1 hour.

I love an over achiever

No normally just the corriordor walls.

Cannot speak for California.

The other twist is,,, does the building have a fire sprinkler system??

How many stories??

 

[cda]

What occupancy type ??

 

[Robert]

2 stories, unsprinklered. If I don't need to do 1 hour for all the walls, which ones (other than corridor walls) will need it? Thanks for clarifying.

 

[Robert]

What occupancy type ??

B and A3 occupancy

 

[cda]

Boy you are getting more complicated

1. So existing business ?

2. One tenant ?

3. How many sq ft per floor

4. Occupant load per type?

Kind of what does this project entail ??

 

[Robert]

Yes, existing office building, one tenant, 6500 sq. ft ground floor, 6200 sq. ft. upper floor, all offices except for 2 occupant loads over 50 and designated Assembly areas/mixed occupancy (2 large meeting rooms).

Project scope is reconfiguring walls for accessible restrooms, remodeling of kitchen and employee lounge and breakroom...no change in square footage or bldg. footprint.

 

[cda]

I want to say the norm is only the corridor walls have to be rated

Look at chapter 10 corridor and the table

Norm is also you only rate or maintain the rating on what you touch walls and doors.

I am wondering if it is rated to begin with?!
Might be an ahj call on what is neede vs code requirement??

 

[steveray]

Yes, it's odd having return air in there. Out of curiosity, since the building is rated as 1 hour construction throughout because of the size, wouldn't that make all of the rooms (including the bathrooms) the same as the corridor with respect to being 1 hour?

Rated "construction" does not require opening protectives (keeps the building from falling down)....fire rated partitions keep the fire from spreading from area to area (rated openings)...

 

[mtlogcabin]

Rated construction would require floor/ceiling assemblies and all supporting construction, walls, posts, beams to be rated. As stated above openings may not be required to be rated.

 

[Robert]

Thanks everyone for clarification! If I'm understanding correctly, floors, ceilings and supporting construction would need the rating...so non-supporting would not? (such as a partition, excluding a rated corridor partition or occupancy separation partition).

The original drawings state 1 hour construction. Also, per table 506.2 CBC (allowable areas), one hour is required for areas over 9000 sq. ft. for B occupancy in a non-sprinklered building ( we are at 12,000+), so it seems to make sense it is rated. As far as the doors go, as I navigate the code, 708.1.3 states corridor walls are fire partitions, and fire partitions per Table 716.5 states fire doors shall be 20 minute rated, which is the direction I'm going unless anyone interprets things differently. As for now, I'm specifying a 20 minute door and frame (without the grill), and asking the mechanical sub to reroute the return air out of the bathroom and to comply with one hour ceiling requirements (which I believe will require a fire damper in the duct).

 

[cda]

Yes twenty minute doors

Not an ibc master,

But are you rating the bathroom ceiling ??

Not sure if you are required to do that?

 

[Robert]

Good question CDA. The bathroom ceiling is outside the corridor. Going back to the 1 hour requirements that mtlogcabin mentioned, would all ceilings and floors be rated in a building required to be 1 hour rated? My gut says yes, since ceiling/roof and floor framing would be considered structural, and protecting those structural elements seems to be the intent of the 1 hour rating.

 

[tmurray]

Good question CDA. The bathroom ceiling is outside the corridor. Going back to the 1 hour requirements that mtlogcabin mentioned, would all ceilings and floors be rated in a building required to be 1 hour rated? My gut says yes, since ceiling/roof and floor framing would be considered structural, and protecting those structural elements seems to be the intent of the 1 hour rating.

If the floor between the first and second storey and the ceiling of the second storey need to be rated, there can be dropped ceilings below the rated assembly that would not be required to be rated. but otherwise, everything structural needs to be rated.

 

[ADAguy]

Only if the ceiling is an extension of the corridor system by not having rated doors to the corridor.
Back in the day we often used rated reception rooms as corridor extensions.

 

[Robert]

To comment on your input ADAguy, if the ceiling is NOT an extension of the corridor, are you saying it does not have to be rated? Isn't the ceiling framing (if not a furred ceiling) considered structural?