Dimensions
What is a bay?
A bay is the horizontal distance between two adjacent standards along a scaffold. Bay length is set by the load the platform has to carry — the heavier the duty, the shorter the bay.
Use this diagram+
Free to use on your own site, in training material or in a course handout, as long as the credit link stays on it. Paste this where you want the diagram to appear.
<figure>
<img src="https://scaffoldoptix.co.uk/glossary/bay/diagram.svg" alt="bay — scaffold diagram from ScaffoldOptix" width="880" height="620" loading="lazy">
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<a href="https://scaffoldoptix.co.uk/glossary/bay">What is a bay?</a> — diagram by
<a href="https://scaffoldoptix.co.uk">ScaffoldOptix</a>
</figcaption>
</figure>Bay length is one of the few numbers on a scaffold that a non-scaffolder will notice, because it is the rhythm of the thing: the spacing of the uprights along the face. It is also one of the most load-sensitive decisions on the whole structure.
The reason is straightforward. Everything on the platform has to reach the ground through the standards, and the further apart they are, the more each one carries and the further the boards and ledgers have to span between them. A scaffold intended for heavy material is set out at shorter bays than one intended for light access.
Bay lengths come from the compliance sheet or the design for the loading class the scaffold is for. They are not adjusted on site to suit the tubes that turned up.
What goes wrong on site
- Bays stretched to make a run reach a corner or an obstruction without going back to the design.
- A scaffold built to one bay length then used for a heavier duty than it was set out for — the commonest way a compliant scaffold quietly stops being compliant.
- Bay lengths measured centre-to-centre in one place and face-to-face in another, so the setting-out drifts along a long run.