A geometric feature provided in an exterior building surface to ensure that flowing water will drip free rather than be pulled back toward a vertical element due to surface tension or gravity. A drip groove is commonly employed in solid materials like concrete whereas a drip edge is used for thinner sheet materials.

                   

Related resources: BSI-050: Parapets—Where Roofs Meet Walls; BSI-051: Decks—Roofs You Can Walk On