188.8.131.52 Insulation. Insulation shall be provided in the exterior
doors, walls, floor and ceiling of the body and shall provide resistance
to transfer of heat in accordance with the requirements of 3.5.6 and
3.5.7. Insulation shall be either foamed-in-place, flexible or batt
type, fibrous or cellular material, having a moisture absorption
capacity of less than 2 percent by weight. If foamed-in-place urethane
insulation is installed, it shall be of a non-formaldehyde based
compound. Materials shall be odorless and fire retardant. Insulation
shall not breed nor promote the growth of fungus and shall not cause nor
accelerate corrosion of steel, copper or aluminum. Insulation shall be
secured to inner side of external walls and provided with means to
retain insulation under all operating conditions. Cement, where used,
shall be waterproof. The installation of the insulation shall provide.
shear strength sufficient to prevent sag of the insulation when
assembled vehicle is operated at speeds up to 55 mph over improved
roads. A vapor barrier shall be installed between the interior panels
and the insulation. A vapor barrier is not required with
foamed-in-place insulation. All insulation, to maximum practicable
extent , shall be installed prior to the closing of spaces in body sides,
front and rear panels, ends, doors, upright body members, roof, roof
bows , and other parts.
3.5.3 Interior panels. The interior of the body sides, front,
rear and ceiling shall be insulated (see 184.108.40.206) and paneled. Foam
tape (or equivalent) shall be installed on frame members, prior to the
installation of the interior paneling. The interior walls shall be
lined full width, height and length with vinyl-coated plywood paneling.
Pressed wood shall not be furnished. Panels shall be installed and
secured with joiners, edgings and moldings. The ceiling shall be
surfaced with Armstrong Reflex V, or equal, hardboard panels.
3.5.4 Floor. Floor crossmembers shall be of adequate size to
support body and payload without fracture or failure under all
combinations of expected loading and shall conform to Federal Motor
Carrier Safety Regulation 393.84. Additional crossmembers shall be
provided, if required to support floor loads in critical stress areas.
Galvanized sheet shall be installed to fully enclose the floor area.
Insulating hardboard shall be secured above the galvanized sheet.
Waterproof plywood shall be installed above the insulating hardboard.
The unit shall be constructed without wheelhousing to provide a
straight-through floor. Underside of floor panels, exposed to road,
shall be sprayed with sound deadening, vibration dampening material.
Wood floor parts, including plywood, shall be treated as specified in