Batt

A flexible slab of thermal insulation made from rock, slag or glass fibres, and used as insulation between joists or studs in frame construction. It is nominally 16 (40.6 cm) or 24 in. (61 cm) wide, and approximately 1 to 6 in. (2.5 to 15 cm) thick. Batts may be 'faced' (with a paper covering on one side) or 'unfaced' (without paper).