rebocos

Rebocos are plaster coatings applied to the exterior or interior surfaces of buildings to provide a finished surface, protect masonry, and improve cosmetic appearance. The finish can be smooth, rough, or textured, depending on the technique and the intended decorative effect.

Rebocos can be based on lime (reboco de cal), cement (reboco de cimento), or a mixture of cement and lime; gypsum-based rebocos exist but are less common for exterior work. Lime-based rebocos are traditional in many regions and are favored for their breathability and moisture regulation, while cement-based rebocos offer greater hardness and faster cure, widely used for exterior walls in damp climates. Finishes with cement-lime mixes or polymer-modified mortars are also used in modern construction.

Application typically involves several coats: a first base coat to level the substrate, a second coat for bonding and structure, and a final finishing coat that provides the final texture and smoothness. Substrates include brick, block, concrete, and stone; surfaces must be clean and dampened to improve adhesion. In rough or irregular substrates, reinforcement meshes or fibrous additives may be used.

Performance depends on substrate, climate, and mix, with lime-based systems being more permeable and crack-prone in movement-prone walls if not properly applied, while cement-based systems resist weathering but can trap moisture if not breathable. Repairs typically involve removing damaged portions and re-applying plaster, followed by painting or sealing.

Rebocos are common in Portugal, Spain, and Latin America, and were historically central to traditional architecture. In modern practice they continue to be used for both restoration and new construction to achieve various architectural finishes.