Acrows
HERMEQ supplies acrow props for temporary structural and load support in construction and refurbishment work. Adjustable acrow props in Sizes 0 to 4 give temporary support to walls, ceilings, floors and beams. Push-pull props brace formwork, shuttering and precast panels at an angle. Fixed and adjustable U-heads fit adjustable steel props and system scaffolding to hold timber or steel beams in place. The PropMate Lintel Support, known on site as a strongboy, carries brickwork during knock-throughs and lintel installation. Both prop types are manufactured in the UK and held as permanent UK stock, with next day delivery.
Acrow props and push-pull props
The range divides by the direction of the load: acrow props stand upright and carry weight down to the ground, and push-pull props brace at an angle to hold walls, panels and shuttering in line.
Adjustable acrow props
Acrow props, also called acrows, steel props, acro props or adjustable steel props, are telescopic steel supports that hold up floors, ceilings, beams and masonry while openings are formed or permanent members are installed. They are the right choice whenever the job is to carry a vertical load. HERMEQ's adjustable acrow props are set close to height on the pin and then wound tight to the load on a threaded adjustment, and the flat plates at each end take a header board, a sole board or a head fitting.
Push-pull props
Set at a rake between the ground or slab and the face of a wall, panel or shutter, these props push or pull it into line and hold it there while concrete cures or permanent fixings go in. They suit bracing precast and tilt-up wall panels, holding formwork shuttering true, back propping during curing and straightening walls in remedial or demolition work. HERMEQ's push-pull props are designed for bracing and alignment under controlled loads, so they do not take the place of vertical acrow props under a floor, beam or loadbearing wall.
Acrow prop sizes 0 to 4
Each size number covers a band of heights between the prop fully closed and fully extended, so the size is chosen from the height of the job.
Small acrow props
Size 0 is the prop buyers look for as a small, short or mini acrow prop. It suits low openings, propping under domestic ceilings and window heads, work beneath stairs and any job where a longer prop would not close down far enough to fit. As the lightest size in the range, it is also the easiest to carry through a house and set by hand in a tight room.
Choosing a size by working height
Across Sizes 0 to 4, adjustable acrow props cover working heights from 1.041m up to 4.876m, and the bands of neighbouring sizes overlap, so many heights can be reached by two sizes. Measure from the surface the prop will stand on to the underside of the load, then take off the thickness of the sole board and header board, or the depth of the U-head or strongboy, to find the height the prop itself has to span. Choose the size that reaches that height inside its range with adjustment to spare, so the prop is not working fully closed or on its last pinhole. A prop that is too short is never made up with timber offcuts or blocks. Push-pull props follow the same 0 to 4 numbering with their own reach for each size, which is listed on their product page.
Propping lintels, beams, floors and formwork
The fitting on top of an acrow prop is chosen by what it supports: a strongboy for masonry, a U-head for beams and the flat top plate for floors and ceilings.
Knock-throughs and lintel replacement
When an opening is formed in a loadbearing wall or a failed lintel is replaced, the masonry above has to be carried while the wall below is cut out. A strongboy lintel support, sold as the PropMate, sits on top of an acrow prop of any size, and its blade passes through a bed joint to pick up both leaves of a cavity wall from one side. The other face stays clear for the work. The slot is cut wide enough for the blade to sit square, and the prop is tightened only until the blade bears firmly on the brickwork, since overtightening can lift the masonry it is meant to hold.
Steel and timber beams
Where props carry timber bearers, steel beams or soffit formwork under a concrete slab, a U-head holds the beam in its slot and stops it moving sideways. A fixed U-head suits repeated runs at one level, where every prop is set to the same height, and an adjustable U-head adds fine adjustment at the head for varying soffit heights, complex layouts or uneven ground.
Floors and ceilings
Propping a floor or ceiling, for example while a wall below it is removed, uses the flat top plate of the acrow prop against a header board, usually a scaffold board, which spreads the load and gives the plate full contact with the surface. A sole board under the base plate does the same on the floor or ground. Each prop is set plumb with a level before it is wound tight, because a prop out of vertical carries load less safely.
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Frequently Asked Questions
What load can an acrow prop carry?
The load an acrow prop can carry depends on its size and on how far it is extended, and capacity is lower at full extension than with the prop nearly closed. For structural work, the temporary works design sets the load each prop carries, along with the number of props, their size and their spacing.
How many acrow props do I need?
The number of props is set by the weight above the opening and the span to be supported, and for structural work the temporary works design gives the count and the spacing. Long openings, older walls with weak mortar and heavy floors over the opening all call for props at closer centres.
Do acrow props need a sole board?
In most cases they do. A sole board, usually a scaffold board, goes under the base plate to spread the load and give the prop a firm, level footing, and it is needed on soft ground, timber floors and any surface that could be crushed or marked. A header board between the top plate and a ceiling or floor does the same job at the head.
When do acrow props need bracing?
Acrow props are braced with scaffold tube and fittings when they stay in place for a long period, when they carry a wide opening, or when they stand beside a live area such as a public walkway or a highway where an impact could dislodge them. The temporary works design states when bracing is required and how it is fixed.
Can acrow props be left in permanently?
No. Acrow props are temporary works equipment and stay in place only until the permanent lintel, beam, wall or slab carries the load, and for concrete, until it has reached the strength the design requires. Props left up for an extended period are inspected regularly and retightened if they have worked loose.