(1) The floors, curbs, and gutters shall be constructed of concrete or other material acceptable to the Secretary. The floors and gutters, if of concrete or concrete base, shall be at least 4 inches thick. The floors, alleys, gutters, mangers, and curbs shall slope lengthwise at a minimum of 1 ½ inches in 10 feet. The cow standing platform and litter alley shall slope at least 1 inch toward the gutter. The cow standing platform in the elevated stall type barn shall slope toward the wall at a minimum grade of 1 ½ inches in 10 feet or this slope requirement may be eliminated with a flush system approved by the Secretary.

(2) A 2-inch minimum radius cove is required at all floor and wall junctions and shall be an integral part of the floor.

(3) The manger, if concrete, gutter and curbs when present, shall be finished smooth with a steel trowel. The cow standing platform, wash pen, litter alley, and feed alley shall be given a true even surface with a wood float. The cow standing platform, litter alley, holding corral, and concrete lane shall be treated to prevent slipping and may be finished either with a suitable instrument, drawn in the direction of both slopes or treatment of the surface with emery aggregate, carborundum grit, or equivalent material. A sand or rock cushion of at least 6 inches shall be placed under the floor on soils other than sandy loam. All concrete floor slabs shall be reinforced with a minimum of #6 x #6/10 x 10 steel mesh or other reinforcing material of equal or greater strength.

(1) The litter alley exclusive of gutter shall be not less than 4 feet 9 inches wide behind a single string of cows or goats. In two-string, head-out barns, the litter alley shall be at least 8 feet wide between gutters.

(2) In floor level barns, the feed alley in single and two-string, head-out types, shall be at least 5 feet 9 inches wide between stanchion line and wall. In two-string, head-in barns, a minimum of 10 feet between lines of stanchions is required.

(3) The milker's alley in the two-string tandem type elevated stall barn shall be at least 8 feet wide, but may be reduced to 5 feet at the narrowest point when automatic feeders are installed and used. The width of the milker's alley in the two-string herringbone type barn may be reduced to 5 feet at the narrowest point.

(4) In the single-string elevated stall type barn, the milker's alley shall be at least 4 feet wide. The milker's alley and passageway if combined shall be at least 8 feet wide.

(1) Gutters in the floor level type barn may be either the trench or step-off type. The gutter shall be at least 14 inches wide and 2 inches deep at the cow standing platform. The gutter floor shall slope down away from the cow standing platform ½ inch across its width. The gutter shall have a uniform depth for its entire length.

(2) The gutters in the elevated stall type barn shall be grate-covered in the stall. The stall gutter shall be located to catch the defecation of the cow in the stall. It shall be at least 500 square inches in area and at least 20 inches wide and 4 inches deep. The herringbone type barns may have the stall gutter width reduced to 14 inches provided the 500 square inch area per animal is maintained. The parallel type barn shall have a 6-inch-wide gutter mounted to the splash panel. Gutter shall automatically flush when cows exit.

(3) Pipe used for barn gutter drainage shall not be less than 4 inches in diameter and meet local plumbing codes.

(1) In elevated type barns, the cow standing platform shall be curbed on the side next to the milker's alley and the curb shall be at least 4 inches in height and designed to retain the elevated stall floor washings. Metal curbs shall be free of voids and sealed to stall floor or wall.

(2) In floor level barns, a curb under the stanchion line at least 6 inches wide and 12 inches high from the stall floor is required, except where metal mangers are used; the top of this curb shall be rounded.

(1) Continuous open (18 inch) ridge vents that rise at least 6 inches above the roof are acceptable. Any ridge vent continuing over the feed room shall be screened fly tight.

(2) Stack type vents are acceptable. Where this type of vent is used, provision shall be made for a 12-inch diameter opening on single-string barns, or a 14-inch diameter opening for multi-string barns, with not more than 10 feet between vent and wall and vent and vent.

(3) When a flat ceiling is installed, it shall have at least two vents, 2 feet by 2 feet or equivalent, shafted to a roof peak vent which has not less than a 12-inch opening. The ceiling vents may be located directly in line over the cow standing platform or over the milker's pit. The vents shall be located not more than 10 feet between vent and wall and vent and vent.