Cantilever Scaffolding System
The cantilever I-beam is the load-bearing member of a flower-basket cantilever scaffold. It reaches out past the floor slab, holds up the working platform, and feeds that load back into the building's frame. Lengge makes these beams from Q235 hot-rolled steel in 16# and 18#, the two sizes that cover most high-rise scaffold jobs. Each beam is welded with a base plate, stiffener ribs and ear plates, then bolted to the side of the structural beam through an embedded part and braced with an adjustable tie rod. The result is a short, triangulated beam that uses far less steel than a long through-wall member and keeps the slab edge intact.
We ship beams on their own or as a matched set with tie rods, turnbuckles and embedded parts. Lengths are cut to your drawing, and finishes come galvanized or painted. Stock sizes load fast for high-rise, commercial and renovation projects.
| Model | Height h (mm) | Flange Width b (mm) | Web Thickness d (mm) | Weight (kg/m) | Steel Grade | Surface Finish | Standard Length |
|---|---|---|---|---|---|---|---|
| 14# | 140 | 80 | 5.5 | 16.89 | Q235 / Q355 | Galvanized / Painted | 6m / 9m / Custom |
| 16# | 160 | 88 | 6.0 | 20.51 | Q235 / Q355 | Galvanized / Painted | 6m / 9m / Custom |
| 18# | 180 | 94 | 6.5 | 24.14 | Q235 / Q355 | Galvanized / Painted | 6m / 9m / Custom |
| 20#a | 200 | 100 | 7.0 | 27.93 | Q235 / Q355 | Galvanized / Painted | 6m / 9m / Custom |
| 22#a | 220 | 110 | 7.5 | 33.07 | Q235 / Q355 | Galvanized / Painted | 6m / 9m / Custom |
It is the main load-bearing member of a cantilever (suspended) scaffold. On high-rise work the scaffold cannot reach the ground, so the beam cantilevers out from each floor slab, holds up the working platform, and carries the load back into the building frame. The beam bolts to the structural beam and a diagonal tie rod braces it, forming a triangle that stays stable as the building goes up.
A traditional cantilever runs a long I-beam through the external wall and anchors it on the floor slab with U-bolts. That uses a lot of steel, cuts holes through walls and slabs, and usually needs a tower crane to place. The flower-basket type bolts a short beam to the side of the structural beam through an embedded part, then carries the load on an adjustable tie rod. It uses far less steel, leaves the wall and slab intact, and the parts come back down for reuse on the next floor.
It comes down to cantilever length, bay spacing and the load on the platform. 16# handles most standard high-rise scaffold bays; 18# steps in for longer reaches or heavier loads. Send us the layout and we will confirm the section and tell you where a lower support rod is needed. Picking the section by guesswork is the most common spec mistake we see.
Yes. We run the full set, from beams to tie rods and closed turnbuckles, high-strength double-head bolts, embedded plastic parts, double-ear rings, washers and protective caps. Buying the matched set means the parts fit together and arrive on one shipment, instead of sourcing each piece separately and hoping the threads line up.
Yes. Beams are cut to your drawing, with common cantilever lengths from around 1300 mm up to 3 m. Finish is your call: hot-dip galvanized for coastal sites and long turnaround, or painted for shorter jobs. We stencil the size on each beam so the right one goes to the right bay on site.
Stock sizes ship quickly; custom lengths and galvanizing add some production time, which we confirm when you order. Beams and accessories load into containers, and a 40 ft high cube takes around 25 tonnes of steel, so freight per ton stays low. We handle export packing and documents for the Middle East, Southeast Asia, Africa and beyond.
If you supply or run scaffolding on tall buildings, the cantilever beam is the part you cannot get wrong. It holds the working platform out in mid-air and passes that weight into the structure. This guide covers what the beam does, how the flower-basket system goes together, how to pick the right size, and what to look at before you place an order. It is drawn from what we deal with on real projects.
A cantilever scaffold is used when the scaffold cannot stand on the ground: past a podium, over a property line, or simply too high to build from grade. The building has to support it. The cantilever I-beam does that job, sticking out from each floor so the scaffold standards sit on it, and the load travels through the beam into the concrete frame. Get the section or the anchoring wrong and the failure shows up at the worst possible height.
The modern flower-basket cantilever is a triangle. The horizontal beam is a 16# I-beam with a base plate, stiffener ribs and ear plates welded on. It bolts flat against the side of the structural beam through a pre-cast embedded part. A diagonal tie rod runs from the outer end of the beam up to an anchor point on the floor above, turning a long horizontal span into a braced triangle. The main parts:
Cantilever beams come in standard reaches. Common lengths are 1300, 1600, 1800, 1900 and 2400 mm, with custom cuts up to about 3 m. Section size follows the load and the reach:
| Cantilever reach | Typical section | Lower support rod |
|---|---|---|
| Up to ~1.5 m | 16# | Not required |
| 1.5 – 1.75 m | 16# / 18# | Recommended at the upper end |
| 1.75 – 3 m | 18# | Required |
16# covers the bulk of high-rise scaffold bays. Step up to 18# for longer cantilevers, heavier platform loads or wider standard spacing. Anything past roughly 1.75 m of reach needs the lower support rod, and beams over 1.8 m usually want temporary pipe propping underneath until the tie rod is tensioned. When in doubt, send the layout and let the supplier confirm.
The old method runs a 3–9 m I-beam through the external wall and bolts it to the slab with three U-anchors. It works, but it is heavy on steel and hard on the building. The flower-basket method was built to fix those problems:
| Aspect | Through-wall cantilever | Flower-basket cantilever |
|---|---|---|
| Steel per beam | Long 3–9 m member | Short braced beam, over 50% less steel |
| Wall & slab | Penetrated, then patched | Left intact, no leak path |
| Tower crane | Needed to place | Hand-set, no crane |
| Reuse | Often cut to remove | Bolted, fully reusable |
Across a tower the steel saving alone is more than half, because you are placing short braced beams instead of long anchored ones. The wall stays sealed, so there is no penetration to patch and no leak path to chase later. And the beams come back down at strip-out for the next job, which is what makes the system pay for itself.
A good beam still has to be set correctly. The points that matter most on site:
Treat the beam as a system, not a steel section. Before you buy, confirm the section and length against your scaffold layout; that the supplier ships the matching tie rods, turnbuckles and embedded parts; the finish (galvanized or painted) against your site conditions and turnaround; and that you will get a mill certificate so the grade on the load matches the spec on the drawing. A supplier who can size it with you is worth more than one who only quotes a price per ton.
