1. (a)

   1. (1) Ceiling and walls shall be insulated with proper material to deaden sound, and to reduce vibration to a minimum.
   2. (2) If thermal insulation is specified, it shall be fire-resistant and meet the requirements of FMVSS 302.

2. (b)

   1. (1) If floor insulation is required, it:

      1. (A) Shall be either five-ply, nominal five-eighths-inch thick plywood, or a material of equal or greater strength and insulation R value; and
      2. (B) Will meet or exceed properties of exterior-type softwood plywood, C-D Grade as specified in the standard issued by the United States Department of Commerce.
   2. (2) When plywood is used, all exposed edges shall be sealed.

Codification Notes: “FMVSS” means Federal Motor Vehicle Safety Standards.