Parapet Wall Height Question

[sooneraia]

OK, I've got a question. IBC 2009, So, I am designing a new auto dealership building, 13,000 sf, B/S-1 occupancies, sprinkled, etc. The building sits on an "open" site, that is we have 25' or more clearance on all sides from the adjacent property. The owner wants to use "rigid frame" construction, ie metal building, well that's fine, we can make it work, the building will be a single slope from front to back. For architectural esthetic reasons, the building has a "square" facade, that is we will have a "parapet wall" on three sides (high side and the two sloped sides). HVAC equipment will be further than 10' in from any exterior wall. In order to achieve the architectural design, a "parapet" must be used, so does this parapet have to be 30" high? Again, we are selecting a parapet for architectural reasons, not fire, so does the "parapet" wall have to be that high? Maybe it's a terminology thing, I should refer to this as a "wall extension or something. Thoughts appreciated.

 

[High Desert]

There are parapets and required parapets. Only required parapets have to meet the 30 inch height.

 

[cda]

Does it meet an exception. 2006 version

Exceptions: A parapet need not be provided on an exterior wall where any of the following conditions exist:

1. The wall is not required to be fire-resistance rated in accordance with Table 602 because of fire separation distance.

2. The building has an area of not more than 1,000 square feet (93 m2) on any floor.

3. Walls that terminate at roofs of not less than 2-hour fire-resistance-rated construction or where the roof, including the deck and supporting construction, is constructed entirely of noncombustible materials.

4. One-hour fire-resistance-rated exterior walls that terminate at the underside of the roof sheathing, deck or slab, provided:

4.1. Where the roof/ceiling framing elements are parallel to the walls, such framing and elements supporting such framing shall not be of less than 1-hour fire-resistance-rated construction for a width of 4 feet (1220 mm) for Groups R and U and 10 feet (3048 mm) for other occupancies, measured from the interior side of the wall.

4.2. Where roof/ceiling framing elements are not parallel to the wall, the entire span of such framing and elements supporting such framing shall not be of less than 1-hour fire-resistance-rated construction.

4.3. Openings in the roof shall not be located within 5 feet (1524 mm) of the 1-hour fire-resistance-rated exterior wall for Groups R and U and 10 feet (3048 mm) for other occupancies, measured from the interior side of the wall.

4.4. The entire building shall be provided with not less than a Class B roof covering.

5. In Groups R-2 and R-3 where the entire building is provided with a Class C roof covering, the exterior wall shall be permitted to terminate at the underside of the roof sheathing or deck in Type III, IV and V construction, provided:

5.1. The roof sheathing or deck is constructed of approved noncombustible materials or of fire-retardant-treated wood for a distance of 4 feet (1220 mm); or

5.2. The roof is protected with 0.625-inch (16 mm) Type X gypsum board directly beneath the underside of the roof sheathing or deck, supported by a minimum of nominal 2-inch (51 mm) ledgers attached to the sides of the roof framing members for a minimum distance of 4 feet (1220 mm).

6. Where the wall is permitted to have at least 25 percent of the exterior wall areas containing unprotected openings based on fire separation distance as determined in accordance with Section 704.8.

 

[Paul Sweet]

This is not a good idea in areas where it snows, unless the metal building is designed for the additional snow load that might get trapped behind the parapet, and the frames are designed for less deflection than metal buildings usually are.

 

[sooneraia]

Does it meet an exception. 2006 versionExceptions: A parapet need not be provided on an exterior wall where any of the following conditions exist:

1. The wall is not required to be fire-resistance rated in accordance with Table 602 because of fire separation distance.

2. The building has an area of not more than 1,000 square feet (93 m2) on any floor.

3. Walls that terminate at roofs of not less than 2-hour fire-resistance-rated construction or where the roof, including the deck and supporting construction, is constructed entirely of noncombustible materials.

4. One-hour fire-resistance-rated exterior walls that terminate at the underside of the roof sheathing, deck or slab, provided:

4.1. Where the roof/ceiling framing elements are parallel to the walls, such framing and elements supporting such framing shall not be of less than 1-hour fire-resistance-rated construction for a width of 4 feet (1220 mm) for Groups R and U and 10 feet (3048 mm) for other occupancies, measured from the interior side of the wall.

4.2. Where roof/ceiling framing elements are not parallel to the wall, the entire span of such framing and elements supporting such framing shall not be of less than 1-hour fire-resistance-rated construction.

4.3. Openings in the roof shall not be located within 5 feet (1524 mm) of the 1-hour fire-resistance-rated exterior wall for Groups R and U and 10 feet (3048 mm) for other occupancies, measured from the interior side of the wall.

4.4. The entire building shall be provided with not less than a Class B roof covering.

5. In Groups R-2 and R-3 where the entire building is provided with a Class C roof covering, the exterior wall shall be permitted to terminate at the underside of the roof sheathing or deck in Type III, IV and V construction, provided:

5.1. The roof sheathing or deck is constructed of approved noncombustible materials or of fire-retardant-treated wood for a distance of 4 feet (1220 mm); or

5.2. The roof is protected with 0.625-inch (16 mm) Type X gypsum board directly beneath the underside of the roof sheathing or deck, supported by a minimum of nominal 2-inch (51 mm) ledgers attached to the sides of the roof framing members for a minimum distance of 4 feet (1220 mm).

6. Where the wall is permitted to have at least 25 percent of the exterior wall areas containing unprotected openings based on fire separation distance as determined in accordance with Section 704.8.

Sure, meets #1. But we still need one for the aesthetics for the building, so if its not required, but still desired it should not have to be 30" high? Correct?

 

[mtlogcabin]

Wind load is another issue to consider in the design

 

[High Desert]

It can be whatever height you design it to if it's not required.

 

[globe trekker]

Might be a Zoning or an local ordinance issue in your location. What does the AHJ require?

.

 

[sooneraia]

Might be a Zoning or an local ordinance issue in your location. What does the AHJ require?.

Actually, the AHJ in our location, is somewhat "uninformed" on the extensive specifics the code may have, don't think they will have much of an issue with anything, especially if I point out the specific code section I was using. I just wish there was a statement in the code saying in effect "parapet walls not required by this code may be any height you want", would sure make this specific question easier. Thanks for the help guys.