Drywall firewall boundries in attic

[sbenson]

Noted two foot wide pieces of drywall nailed to truss's along firewall in a town home built in 1983. I cannot locate any information on this type of fire barrier. ?? any idea's.

[Larry D. Kage]

Originally Posted by sbenson

Noted two foot wide pieces of drywall nailed to truss's along firewall in a town home built in 1983. I cannot locate any information on this type of fire barrier. ?? any idea's.

Well, with a 3 1/2" opening in the drywall, it's breached anyway....

What showed when you peaked into that breach? Was the block wall cut tight with no gaps below the top cord of the truss next to it?

[sbenson]

Block wall extended up past the truss. Truss was butted flush against wall. Roofline's from one unit to next was staggered.

[Claude Lawrenson]

First - is this intended to be a firewall or fire separation?

There is a difference between the two.

[Mario A. Kyriacou, CHI]

Originally Posted by clawrenson

First - is this intended to be a firewall or fire separation?

There is a difference between the two.

Good point Claude!!

"Definitions:
Fire Separation means - A construction assembly that acts as a barrier against the spread of fire. (Note: A fire separation may or may not have a fire rating)
Firewall means - A type of firewall separation of non-combustible construction which sub-divides a building or separates adjoining buildings to resist the spread of fire and which has a fire resistance rating and has structural stability to remain intact under fire conditions for the required fire-rate time.
Fire-Resistance Rating means - The time in hours or fractions thereof that a material or assembly of materials will withstand the passage of flame and the transmission of heat when exposed to fire under specified conditions of Test and Performance criteria, or as determined by extension or interpretation of information derived there from as prescribed in the National Building Code.

[mthomas2]

What's needed there depends: does that wall extend up above the roof and form a compliant parapet? If not, that gypsym borad is needed, but it's not correctly installed:

R317.2.2 Exception: A parapet is not required in the two cases above when the roof is covered with a minimum class C roof covering, and the roof decking or sheathing is of noncombustible materials or approved fire-retardant-treated wood for a distance of 4 feet (1219 mm) on each side of the wall or walls, or one layer of 5/8-inch (15.9 mm) Type X gypsum board is installed directly beneath the roof decking or sheathing for a distance of 4 feet (1219 mm) on each side of the wall or walls.

[Jeffrey R. Pope]

There is no "separation" requirement for the roof structure, only the wall, which is CMU and non-combustible.

[Richard A. Hetzel]

There is no "separation" requirement for the roof structure, only the wall, which is CMU and non-combustible.

Again, beg to differ. If the block wall does not extend as a parapet above the roof, or above the highest roof if there are different heights, then horizontal protection is required on each side of the wall to achieve the required fire-resistance rating.

[Jeffrey R. Pope]

Originally Posted by jpope

There is no "separation" requirement for the roof structure

If you disagree, show me your reference.

I am always willing to learn. . .