Horizontal formwork allowing for extension of support base

A horizontal formwork comprising:

• a plurality of formwork panels;
• a support base comprising a plurality of basic grids on which the plurality of formwork panels are supported, each of the basic grids including first, second, third and fourth vertices and comprising;
• first, second, third and fourth heads arranged respectively at the first, second, third and fourth vertices, each of the first, second, third and fourth heads being respectively supported by a first, second, third and fourth prop;
• first and second main beams arranged parallel to one another, each of the first and second main beams having a first end and a second end, the first end of the first main beam being supported on the first head, the second end of the first main beam being supported on the second head, the first end of the second main beam being supported on the third head and the second end of the second main beam being supported on the fourth head, each of the first and second main beams including a plurality of housings disposed spaced apart from one another;
• first and second edge beams arranged parallel to one another and perpendicular to the first and second main beams, each of the first and second edge beams having a first end and a second end, the first end of the first edge beam being supported on the first head, the second end of the first edge beam being supported on the third head, the first end of the second edge beam being supported on the second head and the second end of the second edge beam being supported on the fourth head, each of the first and second edge beams including one or more support surface for supporting the;
• a plurality of central beams that are arranged parallel to the first and second edge beams, each of the plurality of central beams including a first end and a second end, the first end of each of the central beams being disposed in a respective housing of the first main beam, the second end of each of the central beams being disposed in a respective housing of the second main beam, each of the plurality of central beams including a support surface, the plurality of formwork panels being supported on the support surfaces of the first and second edge beams and the support surfaces of the plurality of central beams;
• at least one of the first and second main beams of one of the plurality of basic grids including a plurality of support sections situated between adjacent central beams, the plurality of support sections each having a support surface, the support surfaces of the support sections being arranged a distance below the formwork panels that allows a plurality of first additional beams to be respectively supported on the support surfaces of the at least one of the first and second main beams in a manner that facilitates a projection of the first additional beams in a longitudinal direction out of the basic grid to increase the support area, the plurality of first additional beams being supported on the respective support surfaces of the at least one of the first and second main beams, the additional beams projecting in the longitudinal direction out of the basic grid to increase the support area, each of the additional beams projecting on both sides of the at least one of the first and second beam.