| 1 | Fixed Base Plate | Flat plate welded to a vertical scaffold standard or spigot | Standard supported scaffolds on firm, level foundations | Hot-dip galvanized carbon steel | Common plate footprints: approximately 120–150 mm square; verify design drawings | Simple, rigid, economical, and easy to inspect | Place on a firm foundation; use mudsills or other adequate foundation where required. Do not use unstable objects to support the scaffold. | OSHA 29 CFR 1926.451(b)(2) EN 12811-1 design framework AS/NZS 1576.1 applications | Material certificate, weld inspection record, dimensional inspection, coating record, and declared design load |
| 2 | Adjustable Screw Jack Base | Threaded stem with base plate, nut, and retaining collar | Leveling uneven ground and correcting small elevation differences | Forged or rolled steel stem with steel plate | Common adjustment ranges: approximately 300–600 mm; verify maximum extension limit | Fast height adjustment while maintaining a continuous load path | Confirm the jack remains within the manufacturer’s extension limit, is fully engaged, and transfers load to an adequate foundation. The scaffold must support at least four times the maximum intended load. | OSHA 29 CFR 1926.451(a)(1) OSHA 29 CFR 1926.451(b)(2) EN 12811-1 AS/NZS 1576.1 | Thread gauge or pitch record, proof-load or design calculation, maximum-extension marking, weld report, and corrosion-protection certificate |
| 3 | Swivel Base Plate | Base plate connected to an articulated or rotating joint | Sloping, irregular, or changing terrain where the scaffold standard must remain vertical | Galvanized steel with forged or machined swivel components | Typical articulation is application-specific; verify permitted angle and load reduction | Improves contact with sloped foundations and reduces point loading | Verify that the joint cannot slip under load and that the supporting surface remains firm and stable. Engineering review may be necessary for non-level or heavily loaded arrangements. | OSHA 29 CFR 1926.451(b)(2) EN 12811-1 AS/NZS 1576.1 | Joint-load test, articulation range, locking mechanism inspection, design calculation, and installation instructions |
| 4 | U-Head Jack Base | Adjustable threaded jack terminating in a U-shaped saddle | Supporting timber beams, steel beams, formwork frames, and shoring heads | Steel stem with pressed or forged steel U-head | Common U-head widths: approximately 100–150 mm; adjustment commonly 300–600 mm | Provides positive seating for beams and helps prevent lateral movement | Use only with a stable load-bearing member seated correctly in the U-head. Check that the scaffold or shoring system is designed for the intended load and braced against displacement. | OSHA 29 CFR 1926.451(a)(1) EN 12811-1 where used in scaffold systems EN 1065 for telescopic steel props where applicable | Head geometry, load-capacity table, proof-load evidence, thread inspection, weld inspection, and installation manual |
| 5 | Base Jack with Spigot | Adjustable base jack incorporating a projecting spigot for the scaffold standard | Ringlock, cuplock, frame, and other modular scaffold systems | Galvanized steel with machined or formed spigot | Common spigot diameter range: approximately 25–38 mm; verify system compatibility | Provides height adjustment while maintaining positive standard alignment | Confirm full insertion depth, compatible standard diameter, effective locking or retention, and adequate foundation support. Do not mix incompatible system components. | OSHA 29 CFR 1926.451(b)(2) EN 12811-1 AS/NZS 1576.1 CSA S269.2 where applicable | Compatibility drawing, spigot dimensions, insertion-depth requirement, load rating, material certificate, and batch traceability |
| 6 | Heavy-Duty Screw Base Jack | Large-diameter threaded stem with reinforced plate and heavy-duty adjusting nut | High-load scaffolds, shoring towers, temporary works, and industrial access structures | High-strength carbon steel, normally galvanized | Typical stem diameters: approximately 32–38 mm; capacity is design-specific | Higher stiffness and improved resistance to buckling compared with light-duty jacks | Capacity must be established for the complete scaffold configuration, including eccentricity, bracing, foundation bearing, and maximum jack extension. OSHA does not approve a product by brand or model. | OSHA 29 CFR 1926.451(a)(1) EN 12811-1 EN 1065 where used as a prop component AS/NZS 1576.1 | Verified design calculation, load-test report, steel grade, thread inspection, weld NDT where specified, and factory quality plan |
| 7 | Articulated or Tilting Jack Base | Adjustable jack with a tilting head or articulated bearing plate | Uneven concrete, ramps, sloped platforms, and specialized temporary works | Steel jack with hardened pin or spherical bearing components | Typical tilt capability is project-specific; commonly limited to a small design angle | Maintains a better bearing interface on sloped surfaces | Verify the allowable angle, locking method, residual capacity, and prevention of sliding. A competent person should review unusual support conditions. | OSHA 29 CFR 1926.451(b)(2) EN 12811-1 AS/NZS 1576.1 | Angle-capacity chart, slip-resistance test, pin and bearing inspection, design calculation, and installation procedure |
| 8 | Caster Jack Base | Adjustable jack or adapter used with a lockable scaffold caster | Mobile scaffolds designed for movement on smooth, level surfaces | Steel adapter with industrial wheel and positive brake assembly | Wheel diameter and jack geometry vary; common wheel diameters are approximately 125–200 mm | Combines mobility with leveling and a positive parked position | Use only where the scaffold is designed as a mobile scaffold. Wheels or casters must be locked when personnel are on the scaffold, and the surface must be level, stable, and free of hazards. | OSHA 29 CFR 1926.452(w) OSHA 29 CFR 1926.451(b)(2) EN 1004-1 for mobile access towers where applicable | Wheel load rating, brake test, swivel-lock test, mobile-tower compatibility, operating instructions, and inspection checklist |
| 9 | Base Plate with Mud-Sill Interface | Fixed or adjustable base plate installed over timber or engineered load-distribution sill | Soil, asphalt, soft ground, and areas requiring greater bearing distribution | Steel plate combined with sound, rated timber or engineered sill material | Sill dimensions are site- and load-specific; commonly selected by bearing-pressure calculation | Reduces bearing pressure and helps prevent settlement or punching of the foundation | The sill must be adequate for the soil and imposed load. The base plate should be centered, fully supported, and prevented from sliding. Inspect for settlement during use. | OSHA 29 CFR 1926.451(b)(2) EN 12811-1 AS/NZS 1576.1 | Ground-bearing assessment, sill material grade, foundation calculation, plate dimensions, site inspection record, and settlement-monitoring plan |
| 10 | Base Jack with Locking Collar | Threaded jack fitted with a captive or positive locking collar to limit unintended rotation | Long-duration scaffold installations and structures subject to vibration | Galvanized or mechanically plated steel | Adjustment range commonly 300–600 mm; collar design and extension limit vary | Helps maintain the selected height and reduces accidental adjustment | Check collar engagement, thread condition, extension markings, and resistance to loosening. The collar does not replace required bracing, ties, or foundation support. | OSHA 29 CFR 1926.451(a)(1) OSHA 29 CFR 1926.451(b)(2) EN 12811-1 AS/NZS 1576.1 | Locking-torque or vibration test, thread and collar inspection, load rating, corrosion-protection record, and traceability documentation |
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