The Common House Martin builds its enclosed mud nest on the outside of the house wall and is the martin one most often sees nesting directly on buildings.
Nest site: an almost completely enclosed mud nest with a small round entrance hole, plastered under the eaves on the outside of the house wall.
Material: hundreds of small pellets of wet mud that are carried there and cemented in place bit by bit, lined with grass stems and feathers.
Colony: several nests are often built close together on the same wall, and the pair may have 2 broods per season.
Modern smooth render and metal cladding give poor grip — a mounted ceramic nest (artificial nest) under the eaves can lure the species back.