Why Facades Deteriorate

A building's facade takes the heaviest beating of any exterior surface, because it's exposed simultaneously to sun, rain, pollution and sharp temperature swings, usually with no roof overhang or shading to protect it.

UV radiation from the sun gradually breaks down the resins holding the paint together, a process called "chalking." The result is a thin, powdery surface that leaves residue on your hand when touched — the first visible sign that the paint has exceeded its useful life. At the same time, air pollution (especially in urban centres like Athens) deposits fine particles that gradually darken the surface, particularly in spots that get less rain to wash them off.

A second, less visible but more destructive mechanism is trapped moisture. When rainwater seeps into small renderRender (plaster)A layer of mortar (sand, cement or lime, and water) spread over brick or concrete to give a wall a straight, sound surface ready for paint or tiles. cracksCrackA 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 can't escape because the paint above it is largely impermeable, pressure builds up behind the paint layer. That pressure causes bubbling, and eventually full detachment in flakesPeeling paintWhen paint loses its grip and lifts off in flakes or sheets. It is almost always a sign of a problem underneath, usually damp or poor preparation. — a phenomenon that gets notably worse in winter, when water frozen inside the cracks expands.

A facade's orientation also plays a major role in how fast it deteriorates. North-facing walls, while they get less direct sunlight, stay damp for longer after each rain, favoring moldMouldFungi that grow on damp surfaces, leaving black or greenish spots and a musty smell. It is a symptom of damp, not a problem with the paint. and moss growth. South- and west-facing walls, by contrast, suffer more from UV exposure and chalking.