Coating is the application of a protective or decorative layer onto a building material such as metal, timber or concrete.
How does a coating work?
A coating forms a barrier between the substrate and its environment. This barrier protects the underlying material against moisture, UV radiation, chemical attack and mechanical wear. Depending on the application, coatings can be liquid-applied (paints, varnishes, epoxies), powder-applied (thermosetting powders cured by heat) or sheet-applied (membranes and films).
A typical coating system consists of multiple layers. A primer provides adhesion and corrosion inhibition. One or more intermediate coats build up film thickness and add protective properties. The topcoat provides the final colour, gloss level and weather resistance. The total dry film thickness (DFT) is specified according to the exposure conditions and required service life.
Types of coatings in construction
- Anti-corrosion coatings — zinc-rich primers, epoxy and polyurethane systems for steel structures
- Intumescent coatings — fire-protection layers that expand when heated to insulate the substrate
- Waterproof coatings — elastomeric or bituminous membranes for roofs and foundations
- Anti-carbonation coatings — acrylic or polyurethane finishes that prevent CO₂ ingress into concrete
- Timber preservatives — stains and lacquers that protect wood against rot and insects
Applications
- Protective treatment of structural steel in bridges and buildings
- Fire-resistant finishing of columns and beams
- Decorative and weatherproof finishing of façade panels
- Sealing concrete floors in industrial environments
- Preserving timber cladding and roof structures
Related terms
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