# Fire-rated Walls Turning Corners?



## fj80 (Apr 11, 2016)

This scenario may be a little hard to explain, but if you have a building with side walls that are 1-hr fire-rated party walls, and front and rear walls that are not fire-rated (because of setback distance from property lines), does the 1-hr fire rating from the side walls have to wrap around the corners of the non-rated front and rear walls some minimal distance? If so, can you direct me to the code section that applies? IBC 2012


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## JBI (Apr 11, 2016)

Fire separation distance only applies to walls that are parallel (or essentially parallel) to the property line, so I believe the rating may stop at the corner.


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## Builder Bob (Apr 11, 2016)

*706.5 Horizontal continuity. *

_Fire walls _shall be continuous from _exterior wall _to _exterior wall _and shall extend at least 18 inches (457 mm) beyond the exterior surface of _exterior walls_. 

*Exceptions: *

   	1. _Fire walls _shall be permitted to terminate at the interior surface of combustible exterior sheathing or siding provided the _exterior wall _has a _fire-resistance rating _of at least 1 hour for a horizontal distance of at least 4 feet (1220 mm) on both sides of the _fire wall_. Openings within such _exterior walls _shall be protected by opening protectives having a _fire protection rating _of not less than 3/4 hour.    	2. _Fire walls _shall be permitted to terminate at the interior surface of noncombustible exterior sheathing, exterior siding or other noncombustible exterior finishes provided the sheathing, siding, or other exterior noncombustible finish extends a horizontal distance of at least 4 feet (1220 mm) on both sides of the _fire wall_.    	3. _Fire walls _shall be permitted to terminate at the interior surface of noncombustible exterior sheathing where the building on each side of the _fire wall _is protected by an _automatic sprinkler system _installed in accordance with Section 903.3.1.1 or 903.3.1.2.    	*706.5.1 Exterior walls. *

	Where the _fire wall _intersects _exterior walls_, the _fire-resistance rating _and opening protection of the _exterior walls _shall comply with one of the following:    	1. The _exterior walls _on both sides of the _fire wall _shall have a 1-hour _fire-resistance rating _with 3/4-hour protection where opening protection is required by Section 705.8. The _fire-resistance rating _of the _exterior wall _shall extend a minimum of 4 feet (1220 mm) on each side of the intersection of the _fire wall _to _exterior wall_. _Exterior wall _intersections at _fire walls _that form an angle equal to or greater than 180 degrees (3.14 rad) do not need _exterior wall _protection.       	2. Buildings or spaces on both sides of the intersecting _fire wall _shall assume to have an imaginary _lot line _at the _fire wall _and extending beyond the exterior of the _fire wall_. The location of the assumed line in relation to the _exterior walls _and the _fire wall _shall be such that the _exterior wall _and opening protection meet the requirements set forth in Sections 705.5 and 705.8. Such protection is not required for _exterior walls _terminating at _fire walls _that form an angle equal to or greater than 180 degrees (3.14 rad).


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## BillS (Apr 12, 2016)

How can a party wall be only 1-HR rated?  I thought that the minimum would be 2.


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## steveray (Apr 12, 2016)

All very good information...And question from Bill.


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## fj80 (Apr 12, 2016)

I misspoke when I called it a party wall. It is not a party wall but rather an exterior wall of my building that is right on the property line, with the neighboring building's exterior right up to the property line as well. So I believe JBI is correct that the fire rating only applies to walls that are parallel, or generally parallel, to the property line, so there is no requirement to provide fire rating around the 90 degree corner to a non-rated wall. Thank you all for your help.


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## Builder Bob (Apr 12, 2016)

*706.1.1 Party walls. *

Any wall located on a _lot line _between adjacent buildings, which is used or adapted for joint service between the two buildings, shall be constructed as a _fire wall _in accordance withSection 706. Party walls shall be constructed without openings and shall create separate buildings. 

*Exception: *Openings in a party wall separating an _anchor building _and a mall shall be in accordance with Section 402.7.3.1.


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## JBI (Apr 12, 2016)

B Bob - In this case each building has a separate wall, so it is not a party wall 'used or adapted for joint service'. Though your earlier post has me thinking that an 18" extension beyond the intersecting walls may be needed...


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## fj80 (Apr 12, 2016)

Yeah, JBI, I am tending to agree with you. My boss said he used to do the 18" extension wall you're talking about when he did townhouses years ago. I don't see a requirement for it in the code anywhere, but it makes practical sense.


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## Builder Bob (Apr 12, 2016)

JBI... Just wanted to ensure that the term party wall was technically identified to prohibit viewers from misconstruing the intent of the code. (non-code people). To clarify, the exterior wall for one structure is structurally independent of the other structure adjacent to it....In other words, you could knock the building down on one side and the remaining structure would remain standing without nay modifications.


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## Builder Bob (Apr 12, 2016)

The extension would be required if a true wall condition existed, the condition that exists in your application is for fire separation distance from the lot lines.....


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## BayPointArchitect (Apr 19, 2016)

Just to clarify, we are talking about 2012 IBC Table 602, Fire-resistance rating requirements for exterior walls based on fire separation distance from a shared / neighboring property line.

Not so much Chapter 7 unless we take a peak at Section 705.5... where that exterior wall is rated for exposure from both sides if it is located less than 10 feet from the property line.

My predecessor required a 5' wrap around the corner but I fail to find that anywhere in the code. Maybe it was a '94 UBC thing. I expect that the rated exterior wall terminate at the corners. No wrap around the corner.

(graphic illustrations would have helped clarify the question)


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