Spray polyurethane foam

Spray polyurethane foam is made from two liquid components that mix in the spray gun. As soon as they leave the gun they expand almost instantly into a light, rigid foam that sticks to the surface. Because it is sprayed, it follows any shape: flat roofsFlat roof (roof terrace)The flat concrete roof on top of a building. It is the most common kind of roof in Greece and the part that takes the most sun and rain., corrugated sheets, metal roofsMetal roof sheetingMetal sheets, flat or profiled, used for roofs and sheds. Light and quick to fit, but they get very hot and rust at the screws and cut edges., the ceiling of a pilotisPilotis (open ground floor)The open ground floor under a block of flats, standing on columns with no walls, usually used for parking or as the entrance., corners, pipes and bases.

Its big advantage is that it forms one continuous layer with no joints, which works as thermal insulationThermal insulationA layer of material that lets heat through only slowly, so a home keeps its warmth in winter and stays cool in summer. and as a barrier to water at the same time. Before spraying, the surface is cleaned and usually given a primerPrimerThe thin first coat that goes on before the main material. It binds dust, seals the pores and helps paint or waterproofing stick firmly. so the foam bonds well.

The foam cannot take the sun on its own: UV light yellows it and slowly wears it away. Outdoors it must always be covered, with an elastomeric coatingElastomeric waterproof coatingA thick, rubbery waterproof paint for flat roofs, parapets and roofs. It stretches without cracking as the building expands and bridges hairline cracks. or a liquid membraneLiquid waterproofing membraneA waterproofing product applied as a liquid by roller, brush or spray. Once dry it forms one continuous, flexible membrane with no seams., or with screedScreedA layer of sand-and-cement mix or lightweight concrete poured over the slab to create falls and a solid surface for the next material. if the roof will be walked on. During spraying, everything around is covered in plastic sheeting and the sprayer wears a protective suit and mask.