Garage Under Stair Protection

[Francis Vineyard]

Can someone point to specific language in the code to require under stair protection in the drawing presented below?

My guess the stairs would be considered habitable in a broad sense as it would not be allowed to not provide protection for similar areas between habitable spaces above the garage.

The underside of the stair is exposed to the garage. The stair is enclosed above to separate it from the garage.

The stair is not a habitable space as defined (similar to halls IMO).

HABITABLE SPACE. A space in a building for living, sleeping, eating or cooking. Bathrooms, toilet rooms, closets, halls, storage or utility spaces and similar areas are not considered habitable spaces.

TABLE R302.6 DWELLING/GARAGE SEPARATION

[TD=align: center] SEPARATION [/TD]

[TD=align: center] MATERIAL [/TD]



[TD=align: left]From the residence and attics[/TD]

[TD=align: left]Not less than 1/2-inch gypsum board or equivalent applied to the garage side[/TD]



[TD=width: 327, align: left]From all habitable rooms above the garage[/TD]

[TD=width: 309, align: left]Not less than 5/8-inch Type X gypsum board or equivalent[/TD]



[TD=width: 327, align: left]Structure(s) supporting floor/ceiling assemblies used for separation required by this section[/TD]

[TD=width: 309, align: left]Not less than 1/2-inch gypsum board or equivalent[/TD]



[TD=width: 327, align: left][/TD]

[TD=width: 309, align: left][/TD]

R302.7 Under-stair protection.

Enclosed accessible space under stairs shall have walls, under-stair surface and any soffits protected on the enclosed side with 1/2-inch (12.7 mm) gypsum board.

 

[JCraver]

Is the stair open on the sides, so the stringers will be exposed, or is there a wall from the garage floor to garage ceiling?

When you say that "The stair is enclosed above to separate it from the garage" - does that mean there is drywall above the stair on all sides, and a solid wood or steel door at the upper-most step / landing?

 

[Francis Vineyard]

Is the stair open on the sides, so the stringers will be exposed, or is there a wall from the garage floor to garage ceiling?When you say that "The stair is enclosed above to separate it from the garage" - does that mean there is drywall above the stair on all sides, and a solid wood or steel door at the upper-most step / landing?

Yes the stair is enclosed with side walls above to separate it from the garage.

 

[Sifu]

Looks to me like 302.7 would not apply since the space is not enclosed. However even though 302.6 points to "habitable space" and the stairs are not considered habitable space I would think the intent to limit the spread of fire into the habitable room above would carry over into the bottom of the stairs. At the least I think I would consider the stairs part of the "residence" which gets to 1/2" protection.

 

[Francis Vineyard]

Think this section of the code (Table 302.6) would be better to state from residence above than "from habitable rooms"?

I believe this has been discussed here in alternate forms but from strict reading of the code the inside of a storage or utility room that opens to the garage would not require finished walls and ceiling. Same if above the garage was a walk-in closet and bath separated by a hall.

 

[Builder Bob]

Don't forget about R501.3 Fire protection of floors.

Floor assemblies, not required elsewhere in this code to be fire-resistance rated, shall be provided with a 1/2-inch (12.7 mm) gypsum wallboard membrane, 5/8-inch (16 mm) wood structural panel membrane, or equivalent on the underside of the floor framing member.

Exceptions:

1. Floor assemblies located directly over a space protected by an automatic sprinkler system in accordance with Section P2904, NFPA13D, or other approved equivalent sprinkler system.

2. Floor assemblies located directly over a crawl space not intended for storage or fuel-fired appliances.

3. Portions of floor assemblies can be unprotected when complying with the following:

3.1. The aggregate area of the unprotected portions shall not exceed 80 square feet per story

3.2. Fire blocking in accordance with Section R302.11.1 shall be installed along the perimeter of the unprotected portion to separate the unprotected portion from the remainder of the floor assembly.

4. Wood floor assemblies using dimension lumber or structural composite lumber equal to or greater than 2-inch by 10-inch (50.8 mm by 254 mm) nominal dimension, or other approved floor assemblies demonstrating equivalent fire performance.

 

[Francis Vineyard]

Bob, Virginia 2012 (along with other states) did not adopt that section and the mandatory sprinkler requirement.

Thanks for the input.

 

[Paul Sweet]

Is there habitable space above the garage? If so, and there is a solid core or 20 minute door at the top of the stairs and gypsum board on the stair walls, that might meet code requirements for separation.