False Floor
Introduction
The subfloor[1][2] or screed is a layer of poor concrete that is used as a mediator between the natural terrain and the floor or screed. The term contrapiso is common in Latin America, while in Spain solera is used.[3][4].
This layer of filling homogenizes the work surface, and allows the traffic loads to be transmitted from the floor to the ground, preventing some movements in the ground due to settlement or expansion from generating cracks in the coating used. The usual thickness is approximately 10 cm. In other Latin American countries it is known as "false floor" when it is in contact with the natural terrain and they call the cement and sand carpet used to receive carpets (carpets) or ceramic floors "subfloor."
The thickness of the subfloor varies depending on its usefulness.
Constitution
It is made with a type of concrete called lean, due to its low binder content and reduced mechanical resistance.
The solera is a metal plate and its measurements can vary. It is commonly used in the manufacture of tools or different metal structures depending on its size.
In ancient times, the sills were built with flat stones placed on the ground as an orthostat. Hence, its use is also extended to sidewalks and/or roads where people or rolling cars travel, which were also built with flat stones arranged horizontally forming a slab.
Currently, these slabs are built with a layer of horizontal concrete with a thickness of 5 to 25 cm - which will depend on the use - poured on compacted ground. It can be made of reinforced concrete, to withstand bending. Between the compacted soil and the concrete layer, another layer of large gravel, of similar diameter and clean, is formed. This serves to prevent the passage of moisture from the ground to the concrete, by capillarity (absorption). Macadam is also used as a sub-base on public roads.
Lightweight subfloor
There is also a type of subfloor that uses cellular concrete or cellular concrete. While traditional underlayment has a density that can reach 2200-2400 kg/m³, lightweight underlayment weighs half or less (900-1100 kg/m³). The advantages of this system are based on the presence of air microcells in the malt composition that give the final product particular characteristics: