Cranes save backs. On a high-rise they do the heavy lifting all day, every day. But plenty of house builds book a crane too, usually for a few hours, and it's worth knowing what's involved so your site is ready when it turns up.
What a crane actually does
A crane is a machine for lifting heavy loads and placing them precisely. It uses simple machines (pulleys, levers and gears) driven by electric motors or hydraulics to multiply human effort. Most cranes do three things:
- Hoist: raise or lower the load on a wire rope.
- Luff: change the angle of the boom or jib, moving the load in or out.
- Slew: rotate the boom or jib left or right to reach different parts of the site.
When does a house build need a crane?
On a typical home, a crane is booked for short jobs such as:
- Roof trusses, especially on two-storey homes or large spans
- Steel beams and columns that are too heavy to lift by hand
- Precast concrete panels or stairs
- Fibreglass or precast pools
- Prefabricated or modular sections
- Large items like a lift, a big water tank or air conditioning plant on a roof
Your builder or the relevant trade (for example, the truss supplier) usually books the crane. Sometimes the delivery truck has its own crane on the back, which can do smaller lifts.
The main types of crane
- Tower cranes: the tall fixed cranes you see on high-rise sites, with a long horizontal jib and counterweights at the back. Luffing tower cranes have a jib that tilts up and down, which suits tight city sites.
- Mobile (slewing) cranes: truck-based cranes that drive to site, set up on outriggers and are ideal for short lifts. This is the one most house builds use.
- Telescopic boom cranes: the boom slides out in sections to change its length quickly. Most modern mobile cranes work this way.
- Crawler cranes: run on tracks instead of wheels, suit soft ground and very heavy lifts, and are mostly used on big infrastructure jobs.
- Vehicle loading cranes: the crane on the back of a delivery truck, often used to drop trusses, frames or bricks straight onto the slab.
Main parts of a tower crane
- Base: a concrete foundation designed by an engineer to stop the crane overturning.
- Mast (tower): steel sections bolted together to reach the height needed. Bolts must be the right grade and correctly tensioned.
- Slewing unit: at the top of the mast, letting the crane rotate.
- Jib: the long working arm that carries the hook.
- Counter jib: at the back, holding the counterweights and often the hoist machinery.
- Operator's cab: where the operator controls the crane and watches the load and wind readings.
Modern cranes also have load moment indicators that warn the operator before a lift exceeds the crane's capacity at that radius, wind sensors, and on busy sites, anti-collision systems to stop two cranes' jibs clashing.
Licences, standards and permits in Queensland
- Licences: crane operators need a High Risk Work licence for the class of crane they're operating, issued in Queensland through WorkSafe Queensland. For example, CT for tower cranes, C2, C6, C1 or C0 for slewing mobile cranes depending on capacity, and CV for larger vehicle loading cranes. The people slinging and directing the load need a dogging or rigging licence.
- Standards: cranes are designed, inspected and used under the AS 2550 series.
- Lift plans: heavier or more complex lifts should have a written lift plan.
- Permits: if the crane sets up on the road or footpath, you'll usually need a council road or footpath occupancy permit and traffic control. If the jib or load swings over a neighbour's property, you need their consent (often called oversail consent).
What a homeowner should know before crane day
- Access: the crane needs a firm, level spot close enough to reach the lift. Soft fill, a fresh driveway or a stormwater pit can't take outrigger loads.
- Overhead power lines: cranes must stay outside the required exclusion zones around power lines. If lines are close, the builder may need to talk to Energex or Ergon well before the lift.
- Neighbours: a heads-up goes a long way, especially if the street will be partly blocked.
- Weather: lifts stop in high winds. A windy day can push crane day back.
- Cost: small mobile cranes are usually charged by the hour with a minimum charge, so make sure everything is ready to lift when the crane arrives. Ask whether crane hire is included in your contract price or the supplier's price.
- Safety: stay well clear of the lift area and never walk under a suspended load.
Quick FAQs
Who books the crane on a house build? Usually the builder or the trade supplying the item being lifted. Check your contract so you know whose cost it is.
What's the difference between a tower crane and a mobile crane? A tower crane is built on a fixed foundation and stays for months on big projects. A mobile crane drives in, sets up on outriggers and leaves the same day.
What stops a lift? High winds, unsafe ground for the outriggers, power line clearance problems, or a load heavier than the crane can handle at that reach.
Further reading
Anthony Painter
