Scaffold Components, Materials, and Fittings
Tubes, couplers, and frames
Tube-and-coupler scaffolds use steel or aluminum tubing joined by couplers. A right-angle coupler fixes two tubes at 90° and is a load-bearing connection. A swivel coupler joins tubes at any angle and is typically used for bracing, not as a primary load path. A sleeve (joint) coupler joins two tubes end to end and must be centered on the joint. Frame scaffolds use end frames, cross braces, guardrail frames, base plates, and screw jacks; the screw jack adjusts for grade, the base plate distributes load, and the mud sill spreads that load over soft ground.
Planking and platforms
Use scaffold-grade lumber or manufactured decking rated for the duty. Inspect every plank: reject splits, large knots, dry rot, warp, and any defect that reduces strength. Planks must rest on both supports with 6 to 12 inches of bearing at each end unless cleated or secured against movement. Manufactured metal planks must have their hooks fully engaged and locking devices seated.
Traps to watch
- Mixing components from different manufacturers - never assume interchangeability.
- Using a swivel coupler where a right-angle coupler is required.
- Tightening couplers by feel instead of to the manufacturer's specified torque.
- Using a damaged or undersized plank because it is needed for only one day.
Rule of thumb: if a component is bent, cracked, heavily rusted, or missing a pin or locking device, tag it out and remove it from service. Worked example: which coupler joins a ledger to a standard at 90° under load? A right-angle coupler, not a swivel.