Protected openings, fire separation

[righter101]

Hello, I will try to make this concise. I searched the topics and didn't see this. Hopefully you guys can help.

2006 IBC used, M occupancy, type 5A (to allow 2 stories).

5A requires 1hr construction (all elements per table 601).

One wall is 5.5 feet from a property line. All others are 20+ feet.

Because the "fire separation distance" is greater than 5 feet, per 704.5 the 1hr rating can be for exposure from the inside. (correct me if i am wrong up until now.)

704.2 "projections" spells out how far the eve overhangs can project. In this case, they project 2 feet, or to a point 3.5 feet from the lot line. Based on 704.2, this is allowable.

The question becomes, refering to 704.2.3 "combustible projections". this is the requirement for 1hr fire rated const, when located where openings are not permitted (less than 3' fire sep.distance), or where they are required to be protected (3-5 ft fire sep dist)(per 704.8).

MY questions: Is this refering to the fire separation distance of the wall, or the actual projection its self?? You would have a wall protected on the inside and the ceiling protecting the roof framing from the underside. Do you need to protect the eves, that are 3'6" from the lot line? Then the next question is, what if those eves have soffit venting?? is that considered an "unprotected opening" in something that is required to be protected??

Thanks in advance for opinions and expertiese.

 

[Builder Bob]

Re: Protected openings, fire separation

Since you brought it up..... Here is what I think the code states - A wall is a wall, unless the eave penetrates the magical distance that only fire can only travel 3 feet, only does the soffit have to be fire rated.

Real World experiences, Wind at 15 miles an hour with a self venting window has traveled almost 12 feet before turning vertical.

717.2.3 Connections between horizontal and vertical spaces. Fireblocking shall be provided at interconnections

between concealed vertical stud wall or partition spaces and concealed horizontal spaces created by an assembly of floor

joists or trusses, and between concealed vertical and horizontal spaces such as occur at soffits, drop ceilings, cove

ceilings and similar locations.

 

[Examiner]

Re: Protected openings, fire separation

Ahh, those soffit vents again in a rated condition. Sometime in the past Code Congress had told me that the soffit vents, although need for attic ventilation, must have a fire damper in a rated roof/ceiling assembly system. They considered the soffit vents as an opening. There are other methods to achieve soffit venting without being located in the soffit. There are low profile vents that can be placed in the lower 2/3 of the roof that can be used for intake. The upper 1/3 of the roof wold be the exhaust near the ridge. Of course the low profile intake vent location may have to be beyond the rated wall toward the inside of the building. The protected construction type you are using would require the rated system to include the soffits to the eaves. That would prohibit unprotected soffit vents but not the low profile intake on the roof deck. The low profile vent would not be any different type of roof penetration as would a plumbing vent or exhaust fan. That is my two cents worth.