What is another word for headlap?
Pronunciation: [hˈɛdlap] (IPA) 
Headlap is a term primarily used in construction, referring to the layer of roof covering that overlaps with the layer below it. Some synonyms for headlap include head flashing, headlap shingle, and headwater. Head flashing specifically refers to the metal or waterproof material that is installed above the roof's headlap to prevent water from flowing into the structure. Meanwhile, headwater refers to the rain that falls on the top of the headlap or flashing and is directed to the roof gutter system. In summary, headlap and its synonyms are all related to ensuring the efficient flow of water away from the roof structure.
