Type VB Construction at 5'-1" and 1" from Interior Lot Line

Type VB construction, 1-story wood framed with prefabricated trusses, restaurant and brewery. The (A-2)restaurant is 4,300 SF the (F-2)brewery is 1,000 SF. Scenario 1-sprinklered building. Scenario 2-unsprinklered.

The question is if our gable end (with 1'-0" overhangs) has the trusses parallel to the wall located 5'-1" from the property line do we just need to protect the exterior wall with a 1-HR fire rated wall from the interior side? Also, I believe the combustible projections can go 12" past the exterior wall and not be fire protected. Is this true if the building is sprinkler or unsprinklered?

Also, what if we were to take a portion of the 1-story building wall and located it 1" off the interior lot line - this portion of the building would have a parapet and flat roof. It's my understanding that this wall would need to be a 1HR wall with a parapet.
Original Post
(Assumes 2009 IBC)

The 2009 IBC and later editions requires exteriors walls to be protected from exposure on both sides if the distance is less than or equal to 10 ft. The 2006 IBC and earlier editions had this distance at 5 ft. So, it depends on the applicable code.

Overhangs can extend a distance of 1/3 the distance between the exterior wall and the lot line. If the building is sprinklered, then the overhang can extend 1/2 the distance. However, in no case can the overhang extend more than 12 inches into the area where openings are prohibited.

Table 602 requires that any wall less than 5 ft. from the lot line must be of 1-hour construction for Groups A and F-2. There are exceptions to the parapet requirement--see Section 705.11.
Okay, thanks. We are using IBC 2003. I found the exceptions to the parapet requirement and this complicates the issue. It appears for 704.11, exception 4. we would have to created a 1 HR protection for any roof trusses and the sheathing that run parallel to the gable end wall and protect an entire girder truss that run perpendicular to the wall that is 5'-1" away from the interior lot line. That's a lot of Drywall.

If the building were to be sprinklered, then it appears that exception 6. would allow us to have the 1HR wall terminate at the underside of the roof sheathing

"704.11 Parapets, Exception 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."

"704.8.1 Automatic sprinkler system.
In buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1, the maximum allowable area of unprotected openings in occupancies other than Groups H-1, H-2 and H-3 shall be the same as the tabulated limitations for protected openings."

Table 704.8 states that 25% of openings with walls between 5' to 10' can be 10% unprotected and 25% protected.

So if the building if fully sprinklered then we can have 25% openings unprotected on our 1HR wall that is 5'-1" away from the interior property line, and take 704.11 Parapets, Exception 6?

Add Reply

Likes (0)