Length is limited by the 1985 Pasteurized Milk Ordinance. In barns where milking is done, the maximum gutter length between dams can not exceed 120 feet. Typical distances between dams range from 40 to 80 feet. If a channel is too narrow, friction may stop the flow of manure. To reduce the size and cost of grates, however, the top width may be 20 to 24 inches.
Dams retain the lubricating layer essential to maintaining flow.
Heights for dams range between 3 and 8 inches, and typical materials are concrete, steel plate, or wooden planks. Caulking may be needed to seal dams. Removable dams facilitate total channel cleanout, when and if it is necessary. Grates made of round or flat steel are generally available commercially for stall barns, as are concrete slats for free-stall barns. Flat grates are recommended if cows must stand on them.