Construction Joints vs Expansion Joints: Where Stremaform® Is Used

Joints are an essential part of reinforced concrete construction, but not every concrete joint performs the same function.

Two of the most common are construction joints and expansion joints. While they may appear similar on drawings or on site, they serve very different structural and construction purposes.

Understanding the difference is particularly important when specifying formwork systems such as Stremaform®, which provides prefabricated stay-in-place formwork solutions for both construction and expansion joint applications.

In this guide, we look at the difference between construction joints and expansion joints, why they are required and where Stremaform® can be used.

What Is a Construction Joint?

A construction joint is created where one concrete pour ends and another begins.

Large concrete structures often cannot be poured in a single continuous operation. Slabs, walls, foundations and other structural components therefore need to be divided into manageable concreting sections.

The interface between these separate pours creates a construction joint, also commonly referred to as a working joint.

The location of construction joints may be influenced by the structural design, reinforcement arrangement, concrete pour sequence, site access and construction program.

Importantly, a construction joint does not necessarily mean the structure is intended to move independently on either side of the joint.

Instead, the objective is generally to allow construction to occur in separate stages while maintaining the required structural relationship between the concrete sections.

What Is an Expansion Joint?

An expansion joint performs a different role.

Rather than simply defining where one concrete pour stops and another begins, an expansion joint deliberately separates structural components so they can move relative to each other.

Concrete structures are subjected to movement caused by factors including temperature changes, shrinkage, structural loading and other environmental or design conditions.

Expansion joints provide a controlled location where this movement can be accommodated.

Depending on the structure, expansion joints may also need to address:

• Shear force transmission
• Waterproofing
• Joint sealing
• Acoustic separation
• Structural movement
• Different component geometries

This makes expansion joint construction potentially more complex than a straightforward construction joint.

Construction Joints vs Expansion Joints: What’s the Difference?

The easiest way to understand the difference is to consider why the joint exists.

Construction Joint

A construction joint primarily exists because the concrete structure needs to be constructed in separate pours.

The adjoining concrete sections remain part of the overall structural system, with reinforcement often continuing through the joint according to the engineering design.

Expansion Joint

An expansion joint exists to provide physical separation between adjoining structural components and allow movement.

Rather than maintaining continuous concrete across the joint, the two components are deliberately separated.

In simple terms:

Construction joint = separates concrete pours

Expansion joint = separates structural components

Both require careful design and execution, but they solve different problems.

Where Is Stremaform® Used?

Stremaform® is a prefabricated stay-in-place formwork system specifically designed for forming joints in reinforced concrete construction.

Unlike conventional temporary joint formwork, Stremaform® remains permanently within the completed concrete structure.

Different Stremaform® configurations are available depending on whether the project requires a working or construction joint, expansion joint, controlled crack joint or a more specialised joint solution.

Stremaform® for Construction and Working Joints

One of the principal applications for Stremaform® is forming construction or working joints between separate concrete pours.

The prefabricated formwork element is installed within the reinforcement at the planned end of the concrete pour.

Concrete is then placed against the element.

Rather than returning after the pour to strip temporary joint formwork, the Stremaform® element remains permanently within the structure.

The adjoining concrete section can subsequently be completed according to the planned construction sequence.

This makes Stremaform® particularly useful where projects involve repeated concrete pours or heavily reinforced structural components.

Does Reinforcement Continue Through a Stremaform® Construction Joint?

Where required by the structural design, reinforcement can continue through a Stremaform® working joint.

This is an important distinction between a construction joint and an expansion joint.

A working joint divides the construction process into separate concreting sections without necessarily creating complete structural separation between them.

The exact reinforcement arrangement and structural requirements must always follow the project’s engineering design.

Stremaform® for Expansion Joints

Stremaform® expansion joint elements are designed to separate adjoining concrete components.

Because expansion joints may need to accommodate movement as well as other structural requirements, their construction can involve significantly more than simply creating a gap between concrete sections.

Depending on the project, expansion joint systems can incorporate additional components for:

• Joint separation
• Waterproofing
• Shear force transmission
• Acoustic separation
• Movement requirements
• Complex component geometries

Prefabricating these elements can reduce the amount of complicated formwork fabrication and assembly required on site.

Why Use Stay-in-Place Formwork for Concrete Joints?

Traditional construction joint formwork is often fabricated on site using temporary materials.

This generally involves constructing the formwork, positioning it around reinforcement, supporting it during concreting and subsequently removing it.

That can become particularly difficult where reinforcement is congested or access to the joint is restricted.

Stremaform® takes a different approach.

Because it is stay-in-place formwork, the element remains within the structure after concreting.

This can eliminate the stripping stage and reduce the amount of temporary joint formwork that needs to be fabricated, handled and removed.

Where Are Construction Joints Commonly Used?

Construction joints occur throughout reinforced concrete construction.

Typical applications include:

Concrete Slabs

Large floor slabs frequently need to be divided into manageable pour sections.

Stremaform® can establish the boundary between these sections while accommodating the required reinforcement arrangement.

Concrete Walls

Walls may be constructed in multiple stages due to their dimensions, concrete volumes or project sequencing.

Stay-in-place formwork can create defined working joints between successive wall pours.

Foundations

Large foundations and heavily reinforced structural elements may require multiple concreting stages.

In these situations, conventional temporary joint formwork can be difficult to fabricate and remove around reinforcement.

Basements

Basement construction often involves multiple wall and slab pours as well as additional waterproofing considerations.

Construction joints therefore need to be carefully planned as part of both the structural and waterproofing design.

Infrastructure

Bridges, tunnels, transport infrastructure, water infrastructure and other major civil works can involve large concrete volumes and numerous planned construction stages.

Prefabricated joint formwork can help simplify these repeated concrete operations.

Where Are Expansion Joints Commonly Used?

Expansion joints are required where the structural design needs adjoining concrete components to accommodate relative movement.

They may be found in:

• Large floor slabs
• Walls
• Long concrete structures
• Commercial buildings
• Multi-storey developments
• Civil structures
• Transport infrastructure
• Water-retaining structures
• Other large reinforced concrete structures

The precise location and configuration of expansion joints is determined by the project’s structural design.

What About Waterproof Concrete Joints?

Waterproofing adds another layer of complexity to concrete joint design.

Basements, tanks, treatment facilities and other structures exposed to water may require construction or expansion joints to prevent water penetration.

Stremaform® systems can be combined with appropriate waterstop solutions for these applications.

For working joints, this can include systems incorporating metal waterstops or rubber water bars.

Expansion joint configurations can also incorporate rubber water bar cages where sealing and movement need to be accommodated within the same joint.

The appropriate solution depends on the project’s engineering and waterproofing requirements.

What Are Controlled Crack Joints?

Construction and expansion joints aren’t the only joints used in concrete construction.

Controlled crack joints are deliberately designed to encourage cracking at a predetermined location.

Concrete naturally undergoes shrinkage and other dimensional changes. Rather than allowing cracks to develop unpredictably, controlled crack joints create a planned weakened section.

Stremaform® controlled crack joint elements can be incorporated into reinforced concrete construction for this purpose and can also be combined with suitable waterstop systems where waterproofing is required.

Construction Joint or Expansion Joint: Which Do You Need?

This isn’t simply a product-selection decision.

The appropriate joint type is determined by the structural engineer and project design.

As a general distinction:

Choose a construction or working joint when:
The structure needs to be divided into separate concrete pours while maintaining the required structural relationship between the sections.

Choose an expansion joint when:
Concrete components need to be physically separated so relative movement can occur.

Other requirements such as waterproofing, shear force transmission, reinforcement continuity and structural loading also need to be considered.

Why Prefabrication Matters

Concrete joint details can become complicated very quickly.

Reinforcement, waterstops, shear dowels, movement requirements and unusual structural geometries can all need to occupy the same relatively small area.

Fabricating these arrangements entirely on site can be labour-intensive.

Prefabricated Stremaform® elements move much of this work away from the construction site.

Depending on the application, elements can be manufactured to suit specific component dimensions and joint configurations before being delivered ready for installation.

This can help reduce on-site fabrication and provide greater consistency across repeated joint locations.

Stremaform® vs Conventional Joint Formwork

The principal difference is that conventional joint formwork is generally temporary, while Stremaform® is designed to remain in place.

Conventional Joint Formwork

Typically requires:

• On-site fabrication
• Installation around reinforcement
• Bracing and support
• Concrete placement
• Subsequent stripping
• Removal and disposal or reuse

Stremaform® Stay-in-Place Formwork

Provides:

• Prefabricated joint elements
• Installation within reinforcement
• No conventional stripping stage
• Reduced on-site fabrication
• Solutions for different joint types
• Project-specific configurations where required

For projects involving numerous or complex joints, these differences can provide meaningful construction efficiencies.

Stremaform® for Complex Concrete Projects

One of the strengths of the Stremaform® system is that it isn’t limited to straightforward, straight construction joints.

Project-specific elements can be produced for complex structural geometries and joint requirements.

This makes the system relevant to major commercial, industrial and infrastructure projects where reinforcement, waterproofing, load transfer and construction sequencing need to be considered together.

Choosing the Right Stremaform® Solution

The appropriate Stremaform® system depends on more than simply whether the project contains a construction or expansion joint.

Important considerations include:

• Joint type
• Concrete element dimensions
• Reinforcement arrangement
• Structural loading
• Required movement
• Waterproofing requirements
• Shear force transmission
• Component geometry
• Construction sequencing
• Site installation requirements

These factors should be considered against the project’s engineering drawings and specifications.

Stremaform® Construction and Expansion Joint Solutions in Australia

Understanding the difference between construction joints and expansion joints is fundamental to selecting the appropriate concrete joint solution.

Construction joints allow large concrete structures to be completed in planned concreting stages, while expansion joints deliberately separate structural components to accommodate movement.

Stremaform® stay-in-place formwork provides engineered solutions for both applications, helping simplify joint construction while reducing the need for conventional temporary joint formwork.

Wright Stone Construction Systems supplies Stremaform® solutions for reinforced concrete projects throughout Australia, including working joints, construction joints, expansion joints and project-specific applications.

For technical information or assistance selecting an appropriate system, explore our Stremaform® Stay-in-Place Formwork Australia range or contact Wright Stone Construction Systems with your drawings, specifications and project requirements.