In the design European standards ISO 4356 i PN-EN 1992-1-1 PN-EN 15037-1 checking deflections of RC bending floor elements was brought about for showing permissible values and overviews of computational methodology. Rigorous requiring the verification of deflections due to the possibility of damage to nonstructural and finishing elements adjoining e.g. to floor elements losing shape and the lack of the legible computational algorithm caused the custom, existing in the environment design, of dimensioning of elements of the load-bearing system at assuming permissible leff /500 values. So a conservative approach in checking the deflection limit state, itself without any-age based on merit, consequently generates unwarranted oversize bending elements of the supporting structure and a substantial increase in the cost of execution of the works.

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