Overlapping consists of bearing elements (beams and plates) and protecting designs (mezhbalochnyh fillings, floors).
Being a bearing and protecting part of a building, overlappings should meet the requirements of durability, rigidity, durability, zvuko - and thermal protections (for garret overlappings and overlappings over prodrivings and cold cellars) and fire resistance.
Considering considerable relative density of cost of overlappings and floors in a total cost of a building (23-26%), to them show increased requirements of profitability and industrialnosti. On a material of bearing designs distinguish overlappings on steel and wooden beams and ferro-concrete.
Under the constructive scheme of overlapping it is possible to subdivide on balochnye and bezbalochnye. In balochnoj to the scheme with flight to 6 m loading from a floor and weight mezhbalochnogo fillings perceive the beams of overlapping stacked on bearing walls with certain distance (step), in parallel smaller party of blocked flight. The step of beams depends on their material and section.
At flights more than 6 m apply beams of larger section (runs). Runs lean against bearing walls or on separate support (columns, columns). Beams of overlappings in this case stack on runs, forming with the last balochnuju a cage. Overlappings from the plates stacked directly on bearing walls, name bezbalochnymi.