Scaffold types
What is a birdcage?
A birdcage is a scaffold built as a grid of standards across an area rather than along a face, giving a single working platform over the whole footprint. It is used for work on ceilings, soffits and roofs from below.
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<img src="https://scaffoldoptix.co.uk/glossary/birdcage/diagram.svg" alt="birdcage — scaffold diagram from ScaffoldOptix" width="880" height="620" loading="lazy">
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<a href="https://scaffoldoptix.co.uk/glossary/birdcage">What is a birdcage?</a> — diagram by
<a href="https://scaffoldoptix.co.uk">ScaffoldOptix</a>
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</figure>Where a facade scaffold is a wall of scaffold, a birdcage is a floor of it. Standards are set out on a grid in both directions, ledgers and transoms run between them, and the platform is boarded across the top so the whole area beneath the work is accessible at once.
It is the standard answer to work on a large ceiling — a church roof, an atrium soffit, a plant room. The alternative, moving a tower around underneath, means the work is done in patches and everything has to line up between repositions.
Birdcages are often built inside, which brings its own considerations: the floor has to take the load, there may be nothing to tie to, and access for material is frequently through a single door.
What goes wrong on site
- Assuming the floor will take it. A birdcage concentrates load at every standard, and an existing floor slab or timber floor is not automatically adequate.
- Nothing to tie to internally, so the structure relies on being a stable grid — which makes the bracing more important, not less.
- Leaving gaps in the boarded top where services or steelwork pass through, without edge protection around the opening.