Asphalt membrane or liquid polyurethane: which is better for the roof terrace?

Both systems are top choices for roof waterproofingWaterproofingThe work and materials that stop water getting through on flat roofs, balconies, bathrooms, basements, planters and tanks. across Attica, but they serve different practical needs.

Asphalt membrane (bituminous sheet) is torch-applied. It comes with a white or grey mineral slate granule topping that shields it from UV rays. Its primary advantage is physical toughness: it stands up well to regular foot traffic, laundry racks, and everyday terraceFlat 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. use. The critical factor is execution: seams between adjacent rolls and parapetParapetThe 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. turn-ups demand meticulous flame welding.

Liquid polyurethane is applied in liquid coats by roller or spray, curingConcrete curingLooking after fresh concrete in its first days: keeping people off it and stopping it from drying out too fast, so it hardens properly and doesn't crack. into a continuous, seamless elastic membrane. It is ideal for rooftops crowded with equipment (solar frames, AC units, piping, skylights), contouring tightly to every transition without joint vulnerability. Furthermore, it adds negligible dead weight to the structure and absorbs structural expansion and contraction easily.

Which one to choose?

• Choose asphalt membrane if your roof terrace is frequently walked on, used for living space, or has an uneven existing 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. requiring heavy-duty protection.
• Choose polyurethane if your roof is crowded with solar fixtures and penetrations, if weight must be minimized, or if you prefer an entirely seamless, highly reflectiveCool 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. white finish.

Regardless of material, thorough surface preparation (power washing, primingPrimerThe thin first coat that goes on before the main material. It binds dust, seals the pores and helps paint or waterproofing stick firmly., and ensuring proper slopesFalls (drainage slope)The gentle slope built into flat roofs, balconies and bathroom floors so water runs to the drain or gutter instead of pooling. to avoid standing water) represents 70% of long-term waterproofing success.