Flat roof is called a substantially horizontal "Roof (construction)" roof, commonly composed of one or several skirts "Flat (architecture)") with a slope of less than 5%.[1]​ Unlike inclined roofs, flat roofs allow people to pass through their surface, as well as the placement of machinery. Conceptually, the operation of a flat roof and a roof or pitched roof are different: while the roof tries to evacuate water, the flat roof collects it to direct it towards the drains.

Contenido

Aunque las cubiertas planas existen desde antiguo en las civilizaciones ubicadas en zonas de escasa lluvia, el auge de este tipo de cubiertas vino de la mano del movimiento moderno y del desarrollo de materiales impermeables capaces de garantizar una buena estanqueidad.

En las sociedades preindustriales, estas cubiertas surgen habitualmente como respuesta a la necesidad de disponer de más espacio habitable en zonas altamente densificadas o con escasa posibilidad de crecimiento. Entre los usos más frecuentes se encontraban: secar el grano, tender la colada, y terraza o incluso dormitorio al aire libre, en climas calurosos.[2]​.

Terraces

Among the first flat roofs are those built with earth or mud, called "terrados".[2]​ These primitive roofs enjoyed a very wide geographical distribution, emerging in places as diverse as southern Europe, North Africa, Central America or the Asian steppe.[2]​ In Spain they were more typical of the Mediterranean basin, although they were present throughout the peninsula. Roofs are usually built on a base of logs, on which a layer of fibers or reeds is placed, which support several centimeters of strongly compacted soil. In more humid climates, it was common to add a final layer of clay, which was much more impermeable. These covers required high maintenance, so in some areas a new improvement was made, by covering the cover with a final protective layer based on lime (Greece), plaster (Tunisia) or ceramic tiles (Cádiz).[2] The evacuation of water occurred through small holes on the sides, called "scuppers".

The Roman architect Vitruvius already detailed the construction system of flat earth roofs protected with a ceramic pavement. The thickness of the layer of earth was estimated at "one foot".[2]​.