built-up roofing; under-roofing
Technical term in construction for a roofing method where multiple layers are built up, or for the underlayer of a roof.
下葺きにはアスファルトルーフィングがよく使われる。
Asphalt roofing felt is often used for built-up roofing.
Compound of 下 (した, 'under') and 葺き (ぶき, the noun form of 葺く, 'to roof').