Key Terms and Concepts from the Text
Cement Fiber (fiber cement)
– made from portland cement, sand and wood fibers. Its is a non-combustible
material and is not prone to decay like wood, plywood, or hardboard. It is a horizontal siding material is almost
rectangular in profile, it is available in 6-in to 12in widths and 3/8-inchs thick. Recommend an overlap of 1-1/4in
and provide trims for use at corners and around openings to match the siding.
– air space between the siding and the sheathing. This space provides a layer for any water that
may infiltrate behind the siding, particularly under windy conditions. This space between the siding and the
sheathing also helps to dry the siding faster and is important consideration for wood siding, which is decay prone.
– Screws are preferred installation because they hold much better then nails.
The boards may be fastened either horizontally or vertically, and have to be fastened to every
– Even though one layer in the norm, sometimes more then one layer is required so that
the fire resistance can be higher
Fire resistance of WLF assemblies
– wall or ceiling-floor assembly depends on the type of drywall panels.
Generally, one 5/8-in, thick, type X drywall panels in each side of a wood stud wall gives a 1 hr fire resistance
rating. Two layers gives a 2 hr, and three gives a 3 hr fire resistance. However, the fire-resistance rating also
depends on the spacing of the studs, spacing, nails or screws, and if the cavity walls were insulated. Fire
resistance design manual gives the specifications and sketches the use of 1,2,3 hr rated assemblies. Because the
ratings are in integer hours, an assembly whose measured fire rating is 1hr means that the material can withstand
fire between 1hr and 1hr59min and so on.
Gypsum board panels
– (most commonly used interior wall and ceiling covering finish in all types of buildings. It
provides a strong, fire-protective cover over faming members, and can be finished with paint, wallpaper, ect. The
water content in gypsum board is what makes the material fire-protective.)
Most Common: 4 X 8ft
Other Sizes: 4 X 9ft, 4 X 10Ft, 4 X 12 Ft
Thickness in residential: 1/2 in
Thickness in Commercial: 5/8 in
Types of Gypsum Board Panels
Type R board (regular): Are the standard board, typically used in ½ in thickness
Type X board: Are most fire-resistive then R-board, the core in type X-board contains noncombustible fibers
mixed with gypsum. The Fibers provide greater strength so that the boards, is subject to fire, maintain structural
integrity for a longer time than type R boards.
-5/8in Board gives 1 hr fire resistance, a board this thick that doesn’t give a 1 hr