Hose Stream Test

The standards also permit the hose stream test to be conducted at the end of the fire endurance test. It is important to understand that the hose stream test is not intended to simulate what happens when the wall is actually hit with a stream of water from the firefighter hose. Instead, it is only intended to develop data about the relative integrity of the wall after a portion of, or during the entire fire endurance test, so that the design professional can make an accurate assessment of the building's safety.

Fire-Resistive Assemblies

A fire-resistant wall is composed of specially formulated fire-resistant gypsum panels, some type of framing (wood or metal studs), fasteners and a joint finishing system (if it is needed). Fire-resistant gypsum panels are classified as "Type X" in accordance with ASTM Standard C1396.

A 5/8-inch gypsum panel is classified as Type X in accordance with ASTM Standard C1396 when it achieves a one-hour rating in accordance with ASTM Standard E119 as applied to both sides of 2-inch by 4-inch wood studs spaced 16 inches o.c. (on center), with the long dimension oriented parallel to the studs and attached to the studs with 1-7/8-inch-long, cement-coated nails spaced 7 inches o.c., with the joints treated with paper tape and joint compound.

Non-combustible walls have achieved one-, two-, three- and four-hour ratings employing steel studs and single or multiple layers of gypsum panels. The most basic one-hour wall is listed in Underwriters Laboratories' (UL) Fire Resistance Directory as Design No. U465. It is composed of a single layer of 5/8-inch Type X gypsum panels on both sides of 25 gauge (18 mil) metal studs spaced a maximum of 24 inches o.c.

Most of the gypsum panels covered in this design must be applied vertically and be attached to the studs with 1-inch-long Type S screws spaced 8 inches apart in the perimeter and 12 inches apart in the field of the panels. The use of thermal insulation for sound purposes is optional in this design.

A standard two-hour system is listed in the directory as Design No. U411. This design specifies a double layer of 5/8-inch Type X gypsum panels on both sides of 25 gauge (18 mil) metal studs spaced a maximum of 24 inches o.c. It is interesting to note that finishing of the joints is not required in this specific assembly. Once again, insulation is optional. An alternative to this is UL Design U412, in which the same two-hour rating can be achieved with two layers of 1/2-inch Type C gypsum panels on both sides of the studs in place of the 5/8-inch Type X gypsum panels.

By adding layers of gypsum panels to each side of the studs, the fire resistance of virtually any wall can be increased by one hour. Design No. U435 covers three- and four-hour ratings with three and four layers, respectively, of 1/2-inch Type C or 5/8-inch Type X gypsum panels.