Base Jack vs Shoring Jack: Key Difference Explained

Don't get confused between base jacks and shoring jacks. It happens all the time on the construction site. Someone uses a screw jack where they need a shoring jack (or vice versa) and the project suddenly gets delayed.

While both are adjustable steel supports used in construction, screw jacks and shoring jacks are designed for completely different purposes. One is built for leveling scaffolding on uneven ground. The other is to support the weight of the concrete and formwork. 

Understanding the difference between a base jack and a shoring jack is important for safety, efficiency and completing your project correctly. Let’s break down what makes these two pieces of equipment different and more importantly, when to use each one.

What is a Base Jack?

A base jack, also called a scaffolding screw jack or leveling jack, is an adjustable steel component that is used at the bottom of scaffolding systems. Base jacks are used to level and stabilize the scaffolding structure.

Think of it as the feet of a scaffold. Just like shoes help you stand properly on uneven ground, screw jacks help scaffolding stay level and stable on uneven ground. Besides, if one side of the ground is slightly lower, workers turn the screw jack to raise that side until the scaffold is straight. 

In simple terms, a base jack is a foundation that keeps your scaffold towers stable and also allows for height adjustment. You can read our complete guide on base jacks to get all the detailed information about them.

What is a Shoring Jack?

Shoring jacks, also called adjustable props, are heavy-duty vertical supports used to hold up formwork and concrete slabs during construction. Unlike base jacks, shoring jacks are not for scaffolding support; they are for supporting heavy loads like concrete, beams and ceilings.

Shoring jacks are often referred to as:

• Adjustable steel props

• Acrow props

• Formwork props

• Construction props

Shoring jacks are used to temporarily support structures during construction or repair work until permanent structural elements are in place. They apply pressure to shoring surfaces and can handle loads up to 20 kN. The load capacity of the shoring jack is greater than that of base jacks.

Features of a Shoring Jack

Adjustable props are designed with the following key features:

Base Plate: A flat steel plate at the bottom distributes the load across the ground or slab. On soft surfaces, a timber or steel pad can be placed under the base plate to prevent sinking.

Top Plate or U-Head: The top of the jack usually has a U-shaped head or flat plate that carries slabs or formwork securely in place. This ensures that the load is evenly transferred from the supported structure to the jack.

Telescopic Tubes: Adjustable props consist of two steel tubes, one sliding inside the other, allowing height adjustment over a wide range.

Threaded Collar/Screw: The screw thread enables fine height adjustments, letting contractors precisely align the supported structure.

Pin Holes and Locking Pins: For coarse adjustments, the inner tube has multiple holes. A locking pin passes through the outer and inner tubes, keeping the jack at the selected height.

What is the Difference Between a Shoring Jack and a Base Jack?

The fundamental difference between base jacks and shoring jacks comes down to purpose and capacity. Base jacks are made for leveling and stabilizing scaffolding systems on uneven ground. In contrast, shoring jacks are built for supporting heavy vertical loads during concrete construction. While both are adjustable and vertical, their purpose is different.

Below are the quick overview of difference between shoring jacks and base jacks:

Load Capacity

Load capacity is the most obvious distinction. A standard base jack safely supports 2-6 tons, which is adequate for scaffolding with workers and materials. By contrast, shoring jacks can handle 20 kN or more, enough to support entire sections of concrete slabs.

Construction and Design

Base jacks use a simple threaded rod mechanism for height adjustments (12–24 inches). Turn the rod and you adjust the height up or down. In comparison, shoring jacks feature telescoping steel tubes, an inner tube that slides inside an outer tube, allowing for much greater height adjustment (5–16 feet).

Adjustment Mechanism

With scaffold screw jacks, adjustment is mostly done by hand or with a wrench, turning the jack nut to raise or lower the scaffold. Conversely, shoring jacks often include hand wheels, multiple locking pins, or heavy-duty collar systems. These mechanisms are designed for adjustment under load and provide the security needed when you're supporting tons of concrete overhead.

Application 

The application is the main difference between base jacks and shoring jacks. Shoring jacks are used in shoring applications to provide adjustable vertical support for temporary reinforcement. If you're pouring a concrete slab or setting up formwork, you need shoring jacks. Alternatively, base jacks provide stability and leveling on uneven ground. If you're building scaffolding, you need base jacks.

Safety Ratings and Standards

Base jacks are rated for the dynamic loads of scaffolding, workers moving around and materials being lifted. The loads shift and change throughout the workday. On the other hand, shoring jacks are rated for the sustained static loads of concrete and formwork over extended periods.

When Should You Use a Shoring Jack?

You should use a shoring jack whenever a structure needs temporary support, including when:

• Supporting concrete slabs during curing

• Holding up beams or walls during alterations

• Installing or removing load-bearing elements

• Providing temporary support during renovations

• Supporting formwork systems

• Repairing damaged ceilings

Can Shoring Jacks be Used on Concrete?

Yes, shoring jacks can be used on concrete. In fact, concrete is one of the best surfaces for placing shoring jacks. The stable surface of a concrete slab or foundation provides excellent bearing capacity for the base plates of shoring jacks.

What are the Advantages of Using a Base Jack?

Base jacks may not carry heavy loads, but they offer important benefits for scaffolding work. Below are the advantages of base jacks in scaffolding:

• Quick ground adaptation

• Easy height adjustment

• Helps scaffolding stay level

• Improves worker safety

• Reduces scaffold movement

• Fast installation and removal

• Cost‑effective and reusable

Which Type of Jack is Best?

The best jack depends on what you're trying to accomplish. Let's break it down by application:

For Scaffolding

Base jacks are best for scaffolding applications. They're specifically designed for this purpose. Don't use shoring jacks for scaffolding. While they might seem like they'd work, they're overbuilt for the application and don't provide the same leveling convenience that base jacks offer. 

For Formwork

Shoring jacks are best for formwork. There's no substitute when you're supporting formwork for concrete pours. Base jacks simply don't have the load capacity or structural design to safely support the weight of concrete, formwork and the associated construction loads.

For Slab Support

Shoring jacks are the only appropriate choice for slab support during concrete construction. Whether you're working on a residential floor slab or a commercial multi-level structure, shoring jacks provide the load capacity and stability required.

Conclusion

Now you know the difference between base jacks and shoring jacks. Although they may look similar, they are not interchangeable. Base jacks are purpose-built for leveling and stabilizing scaffolding on uneven ground, offering moderate load capacities and simple adjustment mechanisms.

In contrast, shoring jacks are heavy-duty vertical supports designed to carry the substantial loads of concrete formwork and slab construction. Using a base jack where a shoring jack is required can lead to serious accidents, while using a shoring jack for scaffolding is unnecessary and inefficient.

By understanding when and where to use each type, you can ensure safer work conditions, better support and smoother construction projects. Remember this simple rule: Base jacks support people and platforms; shoring jacks support buildings and heavy loads.