Exterior wall structures include exterior walls and lightweight composite panels to which an exterior finish is applied. Exterior wall structures may include wooden or
metal studs to which sheathing (e.g., OSB panels or composite sheathing panels) are fastened. A drainage layer can be positioned between sheathing and lightweight composite panels to which an exterior finish is applied. Lightweight composite panels are fastened to sheathing and / or studs by screws, nails, rivets, other mechanical fasteners, and / or
adhesive. Lightweight composite panels can include a
polymer foam core with interior and exterior surfaces and
fiber mesh reinforced cementitious
layers formed over and covering the foam core surfaces. Joints between adjacent lightweight composite panels can be sealed using sealing tape, mesh tape and a seam coat,
polyurethane foam, and / or other sealants. The exterior wall structure is waterproof, fire-resistant, and facilitates application of different finishes, such as
stucco, tiles, or stone, masonry, or
brick veneers.