Used in applications with nuts and bolts. The flat washer provides a greater bearing surface which helps prevent a nut or bolt head from tearing through the material. Flat washers are commonly used in decks and fence building.

It spreads the clamping force over a larger area. Washers may be useful when dealing with soft materials and oversized or irregularly shaped holes. It is usually assembled around a bolt or screw, between the bearing surface of the fastener and the part to which it is attached.