A fire-resistance angle piece and related assemblies include at least one multi-layer portion, which can provide an insulation space and/or a sacrificial layer of the angle piece. The angle piece can comprise vent openings to a space between adjacent layers of the angle piece. In some configurations, adjacent layers of the angle piece can be sealed to one another, such as along an edge portion that can be opposite the vent openings (if present) and/or a fold of the angle piece or other closed end that creates adjacent layers. Intumescent may or may not be included on the angle piece.