A combined wooden frame support and ceiling system is provided, each support including upper and lower wooden chords and a wooden structure connecting the lower chord to the upper chord for weight bearing purposes. A gypsum wallboard batten strip is attached to the lower chord, and defining a ledge extending from each side of the lower chord. A single thickness of gypsum wallboard panels is used to create a ceiling attached to the support, each panel used to create the ceiling is made from a slurry composition including less than 5% by weight of Grade 4 vermiculite. Upon the support being assembled in the ceiling system, with a plurality of the supports, and having lengths of insulation supported by the ledges of the adjacent supports, the ceiling system resists charring by fire for at least one hour.