Caged ladder (ISO 14122-4)

Fixed steel ladder after ISO 14122-4: 65 × 12 flat-bar stiles at 450 mm, Ø25 rungs at 300 mm, stiles extended 1.1 m above the landing, a safety cage (hoops from 2.3 m, five vertical bars) and stand-off brackets. A single flight is used up to 10 m of climb; above that the climb is split into staggered flights of at most 6 m with bracketed rest platforms. Optional top landing on posts with handrails and a self-closing gate. Foot at the origin on y = 0; rungs in the plane z = 0 with the climber and cage on +Z; the structure face and the landing are at z ≤ −0.2, the landing walking surface at y = height.

Installation

Copies structure/ladder.tsx and the shared lib/ into src/components/deck-twin/. Needs three, @react-three/fiber and @react-three/drei. See installation for the manual route.

Usage

import { Canvas } from '@react-three/fiber'
import { OrbitControls } from '@react-three/drei'
import { Stage } from './components/deck-twin/lib/stage'
import { Ladder } from './components/deck-twin/structure/ladder'

export default function Scene() {
  return (
    <Canvas shadows camera={{ position: [8, 5, 9], fov: 35 }}>
      <Stage>
        <Ladder />
      </Stage>
      <OrbitControls makeDefault />
    </Canvas>
  )
}

Props

P&ID

Elevation: two stiles with rungs and hoops of the safety cage; in plan, a short pair of lines with a semicircle (the cage) against the platform edge, labelled LADDER.

Layout plan convention (structural / plot plan drawings); ISO 14122-4

A stair has an inclined flight with an UP arrow; a ladder is vertical. Not on P&IDs.

Typical suppliers

Fabricated to project specification. The geometry is generic and sized from public standards. It is not vendor CAD.

For agents

Machine-readable entry with props, ranges, defaults and ports:

Or fetch /r/ladder.json, or copy a ready-made instruction:

Add the Deck Twin "Caged ladder (ISO 14122-4)" component to this project. Run `npx -y https://decktwin.com/cli/deck-twin-0.2.2.tgz add ladder` (it copies the file and the shared lib into src/components/deck-twin/), then `npx -y https://decktwin.com/cli/deck-twin-0.2.2.tgz info ladder` for its props, ranges and ports. Render <Ladder /> inside a React Three Fiber <Canvas shadows>, wrapped in <Stage> from src/components/deck-twin/lib/stage. Set props from my data (metres, NPS in inches, ASME class) and leave the rest at defaults. Install three, @react-three/fiber, @react-three/drei and @types/three if they're missing. Full guide: https://decktwin.com/skill/SKILL.md