Category: Structure & materials
Prepared by Eng. Ahmed Fathy, Projects Manager ·
Definition
A hidden beam is a concrete beam as deep as the slab, so the ceiling stays flat. It makes up for its shallow depth with more width and steel, and is common with hollow block slabs in villas.
Why it matters on a project
It gives a clean ceiling that is easier to finish and needs less gypsum, but it is less efficient than a drop beam on long spans and can add steel and deflection.
Measurement and pricing
Concrete in cubic metres within the slab or separately, steel in tonnes from the bar bending schedule.
Common mistake
Using hidden beams on long spans without checking deflection, so sagging and cracks appear in tiles and walls.
Frequently asked questions
Is a hidden beam better than a drop beam?
Not always. It gives a flat ceiling, but a drop beam is structurally more efficient on long spans.
Do hidden beams need more steel?
Usually yes, because the lower depth needs more reinforcement for the same load.
Related terms
- BeamA horizontal element that carries the slab and transfers its loads to the columns.
- Hollow-block (ribbed) slabA slab with concrete ribs between hollow blocks to reduce weight and increase spans.
- Solid slabA concrete slab of uniform thickness without voids, common for small and medium spans.
- Bar bending schedule (BBS)A schedule listing the diameter, length, shape and number of reinforcement bars per element.
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