Measures · RC cantilever / balcony
Reinforced concrete cantilever and balcony pre-sizing FREE
Work out the thickness of a reinforced concrete cantilever or balcony from its projection. Below the result you find the formula and the standard.
Indicative pre-sizing. It does not replace a structural calculation signed by a licensed engineer. For seismic zones with agS (design ground acceleration) > 0.15g, long spans or use classes III/IV → talk to a structural engineer.
Pick a calculation from the list to start.
Formula, example and standard
h ≈ Ls/8 ÷ Ls/10 (stricter than a beam)
Example with the starting values (Projection Ls: 1.2 m): Beam depth h ≈ 12–15 cm. Min slab thickness: 12-15 cm.
- Cantilevers are stricter than simple beams (high moment at the fixed end).
- Slab min 12-15 cm to resist bending + the fixed-end moment.
- The deflection check matters most here (the L/250 limit often governs).
Source: NTC 2018 §4.1 · marcodepisapia.com
Indicative pre-sizing: it does not replace a calculation signed by a licensed engineer.
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