Rip Rap Armor Stone Rip Rap

Rip rap is large, angular rock you dump along shorelines, drainage ditches, and steep slopes to stop moving water from washing the soil away. The stones are heavy and irregular, so they wedge into each other and stay put when fast water hits them. Pieces run from about 4 inches across up to 36 inches, and it's usually quarried from granite, limestone, or sandstone.

Rip rap's sold by class instead of a screen number like #57. Light rip rap is roughly 4 to 12 inches, medium runs 12 to 24, and heavy is 24 to 36. Each class mixes a range of sizes on purpose so the small stones wedge into the gaps between the big ones. You'll pay by the ton, and a cubic yard of dumped rip rap weighs about 1.2 to 1.7 tons depending on the rock type.