Elastomeric waterproof coating

An elastomeric coating is a thick paint, usually acrylic-based, that stays rubbery once dry. That lets it follow the small movements of a roof slab with heat and cold without crackingCrackA split or gap in render, concrete, a wall, a coating or wood. Fine cracks are usually only on the surface; ones that grow, keep reopening or run diagonally need attention., and bridge hairline cracks.

It is used as the top coat on 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., over spray polyurethane foamSpray polyurethane foamA foam sprayed on as a liquid that expands on the spot and sets into one seamless layer. It insulates against heat and cold and closes cracks and joints. to protect it from the sun, on parapetsParapetThe low wall around the edge of a flat roof or balcony. The joint between it and the floor is one of the most common places for leaks., on corrugated sheets and on walls that need something tougher than ordinary paint. In white it reflects the sunCool roof coatingA white or very light top coat that reflects much of the sun's radiation, so the roof and the floor below heat up less. and keeps the space below cooler.

Not all elastomeric coatings are the same: some can take foot traffic and standing water and others cannot. The surface must be clean and primedPrimerThe thin first coat that goes on before the main material. It binds dust, seals the pores and helps paint or waterproofing stick firmly., and the material applied at the thickness the manufacturer specifies, in more than one coat. It needs renewing over the years.