Telescopic Formwork Support
An adjustable steel prop is a telescopic steel post that supports formwork and loads during construction. It extends and locks to the height you need, holds up slab and beam formwork while the concrete is poured and cures, and shores structures temporarily. Known in many markets as an acrow prop, it is one of the most-used items on any concrete job. Lengge makes them in standard and heavy-duty grades, with plate, U-head and push-pull options, in painted or galvanized steel.
We hold the full size range in bulk and ship by the container, factory-direct for contractors, formwork firms and dealers worldwide.
| Item | Specification |
|---|---|
| Type | Adjustable steel prop (acrow prop / shoring prop) |
| Construction | Telescopic inner and outer tube |
| Adjustment | Pin holes for coarse height, threaded collar for fine |
| Ends | Base and top plate, U-head fork, or swivel (push-pull) |
| Sizes | Standard size range, around No.0 to No.4 (to BS 4074) |
| Capacity | Rated safe working load by size and extension |
| Material | Steel |
| Finish | Painted or hot-dip galvanized |
Size, end type, duty and finish are made to your requirement. Tell us the heights and loads and we match the prop to the job.
An adjustable steel prop is a telescopic steel post used as a temporary vertical support in construction. An inner tube slides inside an outer tube; a steel pin through holes sets the coarse height, and a threaded collar adjusts it finely and takes the load up tight. It mainly holds up formwork while concrete is poured and cures, and it is also used to shore or support structures temporarily.
It is the same thing. Acrow prop is the common name for an adjustable steel prop in the UK and many other markets, after a well-known maker, and the name has stuck as a general term. Whether it is called an acrow prop, a shoring prop, a scaffolding prop or an adjustable steel prop, it is the same telescopic steel support.
Props come in standard size classes, often numbered from around size 0 up to size 4, each covering a range of heights from closed to fully extended. A smaller size suits low work like a single storey; the larger sizes reach the higher floor-to-soffit heights. We supply the full range of sizes, and can confirm the closed and extended height of each so you can match it to your job.
The standard prop has a flat base plate and top plate and is the general workhorse. The U-head prop has a fork head that holds a timber or steel formwork beam, used under slab and beam forms. The push-pull prop has one fixed and one adjustable leg with swivel ends, used to brace and plumb wall formwork rather than to carry vertical load. Heavy-duty versions use thicker tube for higher loads. We supply all of these.
Props are steel, finished either painted or hot-dip galvanized. Galvanizing lasts longer through repeated use and outdoor exposure, which matters because props are reused across many pours. Tell us your preference and the duty, and we supply to suit.
We supply adjustable steel props in bulk and ship by the container. Stock moves quickly; large or custom orders we confirm at the time. Props nest and bundle efficiently for shipping, so freight per piece stays reasonable, and we handle export packing and documents.
Wet concrete cannot hold itself, and neither can the formwork shaping it. Until the concrete cures, something has to carry that weight, and on most jobs that something is a line of adjustable steel props. They are simple, strong and everywhere on a concrete site. This page covers how a prop works, the standard sizes, the types, and how to choose one safely.
An adjustable steel prop is two steel tubes, one sliding inside the other, so the prop telescopes to different heights. The coarse height is set by dropping a steel pin through matching holes in the tubes. The fine adjustment, and the final tightening up under the load, is done by a threaded collar, a large nut that winds along the thread on the outer tube. Set the pin near the height you want, then wind the collar up until the prop is tight under the formwork. That combination of a pin and a thread is what lets one prop both span a range of heights and take the load up snug.
Props are made in standard size classes, each covering a band of heights from closed to fully extended. The widely used set, to BS 4074, runs roughly as follows:
| Standard size | Closed height | Extended height |
|---|---|---|
| No.0 | 1.07 m | 1.83 m |
| No.1 | 1.75 m | 3.12 m |
| No.2 | 1.98 m | 3.35 m |
| No.3 | 2.59 m | 3.96 m |
| No.4 | 3.20 m | 4.88 m |
The figures above are the common standard ranges; exact closed and extended heights vary a little by maker, so confirm them for the props you order. Pick the smallest size that comfortably reaches your height, because a prop used near the bottom of its range is stiffer and carries more than one stretched to its limit.
The standard prop has a flat base plate and top plate and is the general-purpose support under slab and beam formwork. The U-head prop swaps the top plate for a fork, or U-head, that cradles a timber or steel formwork beam and stops it rolling, used in slab and beam falsework. The push-pull prop is different in purpose: it has one fixed leg and one adjustable leg with swivel ends, and it is used to brace and plumb wall and column formwork, pushing or pulling the form into line rather than carrying vertical load. Heavy-duty props use thicker wall tube to carry higher loads at the same heights.
The key safety point with props is that the safe working load is not a single number, it falls as the prop is extended. A prop near closed can carry much more than the same prop wound right out, because the longer the extension, the more slender the prop and the more it can buckle. Always work to the rated load for the size and the actual extension, set props plumb on a firm base with the load central, and brace tall props or rows of props where the design calls for it. Overloaded or over-extended props are a common cause of formwork collapse, so the rating and the bracing are there to be followed.
Props are steel, painted or hot-dip galvanized; galvanizing lasts better through the reuse and weather a prop sees over its life. When buying, match the size class to your floor-to-soffit heights, choose the end type (plate, U-head or push-pull) to the job, and confirm the duty and the rated loads. Props ship and store efficiently in bundles, so for export the main things to confirm are the sizes, the quantity per size, and the finish.
