Why is it called a spandrel beam?

It sits in the spandrel zone of the outer wall, the strip between the windows of one floor and the floor above, so it took that name.

Why do spandrel beams twist?

Slab load comes in from one side only, which creates torsion. Interior beams have slab on both sides, which mostly balances out.

Is a plinth beam a spandrel beam?

No. A plinth beam ties the columns at ground level above the foundation. Spandrel beams are the outer edge beams at floor and roof levels.

What is a spandrel beam and why it needs extra care

Updated 31 October 2026

In this guide

What a spandrel beam is
How it differs from an interior beam
What this means for reinforcement
Site checklist

What a spandrel beam is

A spandrel beam is a beam on the outer edge of a floor, running between the outer columns. It carries the slab on one side only, plus the outer wall, parapet, or cladding resting on it.

The word spandrel originally meant the roughly triangular wall space between an arch and the frame around it. In framed buildings it came to mean the wall strip between the top of one window and the bottom of the next, and the beam behind it took the same name.

How it differs from an interior beam

Load from one side only: an interior beam has slab on both sides, which balances out. A spandrel beam has slab on one side, which tries to twist it. This is called torsion.
Heavy wall load: the outer wall is usually a full brick or block wall with openings and is heavier than inside partitions.
Weather exposure: the outer face sees sun, rain and temperature changes, so concrete cover and quality matter more.
Lateral role: in earthquake areas, edge beams are part of the frame that holds the building together sideways.

What this means for reinforcement

Because of torsion, spandrel beams often need closed stirrups with proper hooks and closer spacing, and sometimes extra side bars on the faces of deep beams. IS 456 has specific provisions for designing beams for torsion, and IS 13920 adds ductile detailing for seismic zones like west UP. The engineer works this out. On site your job is to build exactly what is drawn.

Site checklist

Stirrups closed with 135 degree hooks where the drawing calls for them, not 90 degree bends.
Stirrup spacing near columns as per the drawing, usually closer than at mid span.
Side face bars present in deep beams.
Proper cover blocks on the outer face to keep rain and rust away from the steel.
Good vibration and curing on the exposed face.

Frequently asked questions

Why is it called a spandrel beam?: It sits in the spandrel zone of the outer wall, the strip between the windows of one floor and the floor above, so it took that name.
Why do spandrel beams twist?: Slab load comes in from one side only, which creates torsion. Interior beams have slab on both sides, which mostly balances out.
Is a plinth beam a spandrel beam?: No. A plinth beam ties the columns at ground level above the foundation. Spandrel beams are the outer edge beams at floor and roof levels.