In the realm of reinforced concrete construction, one vital element that often takes the backstage but plays a crucial role is the slab bolster. While it might not be the star of the show, its significance in maintaining the structural integrity and durability of concrete slabs cannot be overstated. In this comprehensive guide, we’ll dive into the world of slab bolsters, exploring their purpose, types, installation, and benefits. So, let’s roll up our sleeves and unravel the core aspects of this unassuming yet indispensable construction accessory.

Table of Contents

1. Introduction
2. What are Slab Bolsters?
3. The Role of Slab Bolsters in Concrete Construction
4. Types of Slab Bolsters
5. Importance of Proper Installation
6. Advantages of Using Slab Bolsters
7. Factors to Consider When Choosing Slab Bolsters
8. Installation Process Step-by-Step
9. Common Mistakes to Avoid
10. Tips for Efficient Slab Bolster Usage
11. Conclusion


Concrete is the backbone of modern construction, and its strength is further augmented by the incorporation of reinforcement bars. While the rebar grid provides tensile strength, the role of slab bolsters in ensuring proper positioning and support for these bars is often underestimated.

bolster concrete

2.What are Slab Bolsters?

Slab bolsters are small, yet mighty, devices used in concrete construction to raise the height of reinforcing bars above the formwork. These elements are carefully designed to maintain the required spacing between the top and bottom layers of rebar, ensuring optimal concrete coverage and preventing potential weaknesses.

3.The Role of Slab Bolsters in Concrete Construction

Imagine a scenario where rebar is not adequately supported and ends up sinking within the concrete mix. This could lead to uneven load distribution and compromised structural integrity. Slab bolsters come to the rescue by providing consistent elevation and support, thereby contributing to the longevity of the concrete slab.

4.Types of Slab Bolsters

4.1 Single-Directional Slab Bolsters

Single-directional slab bolsters are primarily used when the rebar is placed in a single layer. They offer straightforward support and are often employed in applications where lighter loads are anticipated.

Single-Directional Slab Bolsters

4.2 Cross Slab Bolsters

Cross slab bolsters, as the name suggests, are designed to cradle two layers of rebar crossing each other. This type of bolster provides stability and ensures that the upper layer of rebar is positioned accurately above the lower one.

4.3 Circular Slab Bolsters

Circular slab bolsters are used in scenarios where circular or curved sections of concrete are being formed. These bolsters are designed to accommodate the unique shape of the structure while maintaining the necessary spacing between the rebar.

Circular Slab Bolsters

5.Importance of Proper Installation

The effectiveness of slab bolsters hinges on their correct installation. Let’s delve into some crucial installation steps and considerations.

5.1 Ensuring Correct Positioning

Before pouring the concrete, it’s imperative to place the slab bolsters at the designated spots. This involves meticulous planning and alignment to ensure that the rebar ends up in the right position.

5.2 Maintaining Required Spacing

Achieving the ideal spacing between the rebar layers is essential for uniform concrete coverage. Slab bolsters play a pivotal role in maintaining this spacing, preventing issues such as insufficient concrete encapsulation and potential corrosion.

6.Advantages of Using Slab Bolsters

6.1 Enhanced Load Distribution

Properly spaced and supported rebar ensures that the load distribution across the concrete slab is uniform. This translates to improved load-bearing capacity and a reduced risk of structural failure.

6.2 Prevention of Concrete Cracking

Cracks in concrete can lead to a plethora of problems, including decreased durability and aesthetics. Slab bolsters help in maintaining the integrity of the concrete by preventing cracking due to inadequate support.

6.3 Facilitation of Reinforcement Placement

Installing rebar in intricate configurations can be challenging. Slab bolsters simplify this process by providing a stable platform for the rebar, ensuring accurate placement according to design specifications.

upper slab bolster

7.Factors to Consider When Choosing Slab Bolsters

The selection of slab bolsters should take into account various factors to ensure their compatibility and effectiveness.

7.1 Load Requirements

Different construction projects entail varying load-bearing requirements. Choosing the appropriate slab bolster strength and design is essential to meet these demands.

7.2 Slab Thickness

The thickness of the concrete slab influences the choice of slab bolsters. Thicker slabs may require higher elevations to maintain optimal rebar positioning.

7.3 Environmental Conditions

External factors such as weather, moisture, and temperature can impact the performance of slab bolsters. Selecting materials that are corrosion-resistant and suitable for the environment is crucial.

8.Installation Process Step-by-Step

8.1 Pre-Installation Preparation

Prepare the construction site by ensuring the formwork is properly set up. Clear any debris and create a clean, level surface for the concrete placement.

8.2 Placing the Slab Bolsters

Carefully position the slab bolsters according to the project’s design and spacing requirements. Double-check the alignment to avoid errors during the concrete pouring stage.

8.3 Securing the Bolsters in Place

To prevent displacement during concrete pouring, secure the slab bolsters using appropriate tie wires or other fastening methods. This ensures that the bolsters remain in their designated positions.

9.Common Mistakes to Avoid

9.1 Inadequate Spacing

Insufficient spacing between rebar layers can lead to weak points in the concrete. Avoid this pitfall by diligently following spacing guidelines and utilizing slab bolsters.

9.2 Incorrect Height Adjustment

Failure to maintain uniform height for slab bolsters can result in uneven rebar positioning. Regular checks and adjustments are crucial to prevent this issue.

9.3 Neglecting Quality Assurance

Cutting corners on quality control can lead to costly rework and compromised structural integrity.  Regular inspections and quality assurance protocols are indispensable.

10.Tips for Efficient Slab Bolster Usage

10.1 Regular Inspection and Maintenance

Once the concrete slab is in place, continue to monitor and inspect the slab bolsters. Replace any damaged or corroded bolsters promptly to ensure ongoing support and stability.

10.2 Complementing with Other Accessories

Slab bolsters work in harmony with other concrete accessories such as chairs, spacers, and tie wires. Using a combination of these elements can optimize reinforcement placement.


In the intricate dance of reinforced concrete construction, the slab bolster takes on the role of a reliable supporting partner. Its unassuming presence contributes significantly to the durability, strength, and longevity of concrete slabs. By ensuring proper rebar positioning and spacing, slab bolsters play a vital part in upholding the integrity of structures. So, next time you marvel at a well-constructed concrete surface, remember the unsung hero beneath – the slab bolster. We are supplier of various type of slab bolster, welcome to inquire.

slab bolster package


Q1: What are slab bolsters made of?

Slab bolsters are commonly made from materials such as plastic, steel, or wire.

Q2: Can slab bolsters be reused?

Yes, slab bolsters that are in good condition can be reused for multiple construction projects.

Q3: Are there adjustable slab bolsters available?

Yes, some slab bolsters come with adjustable heights to accommodate varying slab thicknesses.

Q4: How do slab bolsters prevent corrosion?

Corrosion-resistant materials or coatings on slab bolsters prevent them from reacting with concrete and moisture, thus reducing the risk of corrosion.

Q5: Can I use chairs instead of slab bolsters?

While chairs can also provide support for rebar, slab bolsters are specifically designed for maintaining proper spacing and elevation between rebar layers.