Sill_plate
Sill plate
Bottom horizontal member of a wall which vertical members are attached to
A sill plate or sole plate in construction and architecture is the bottom horizontal member of a wall or building to which vertical members are attached. The word "plate" is typically omitted in America and carpenters speak simply of the "sill". Other names are rat sill, ground plate, ground sill, groundsel, night plate, and midnight sill.[1][2][3]
Sill plates are usually composed of lumber but can be any material. The timber at the top of a wall is often called a top plate, pole plate, mudsill, wall plate or simply "the plate".