TM 5-852-9/AFR 88-19, Vol. IX
wood beams, and arches can burn for several hours without collapsing, however. Wood frame structures are
frequently finished with 5/8-inch fire rated Type X gypsum board to provide 1-hour fire-rated construction.
Fire-retardant treatments which increase wood's fire resistance should be used on wooden structural members
and wood finishes exposed to the interior. Nails, screws, and other fasteners must be compatible with the
chemical used in fire-retardant treatments. Intumescent foaming paint may also be used for fire protection,
particularly to modify old structures or where other methods are impractical. Non-combustible metal studs
are an acceptable and common alternative to wood studs. A thermal break must be incorporated when metal
studs are used in a thermal insulating wall, however (see figure 2-1).
(3) Frost buildups. Fewer frost buildup problems are encountered in wood frame construction