When you’re working on slabs over reactive soils, void formers aren’t optional, they’re critical.
For formwork companies, concreters and builders, the right void former can mean the difference between a smooth pour and ongoing slab movement issues down the track. Strength, consistency, delivery timing and ease of install all matter on-site and cutting corners can be costly.
This is where honeycomb void formers have become the preferred solution across commercial, residential and infrastructure projects.
In this guide, we’ll break down:
- What void formers do and why they matter
- Why honeycomb board is increasingly used in formwork
- How to choose the right thickness for your slab
- And where to buy Australian-made honeycomb void formers online, ready for site delivery
WHAT IS A VOID FORMER
A void former is a temporary form placed beneath a concrete slab to create a void space. This allows reactive soils to expand and move without exerting upward pressure on the slab above.
Formwork companies rely on void formers to:
- Protect structural integrity
- Reduce long-term slab movement
- Meet engineering and compliance requirements
- Maintain consistency across large slab areas
In reactive soil conditions, common across many parts of Australia – void formers are a standard part of slab design.
Unsure which void former thickness your slab needs?
WHY HONEYCOMB VOID FORMERS ARE THE PREFERRED OPTION
Compared to traditional alternatives, honeycomb cardboard void formers are purpose-built for modern construction sites.
Benefits formwork teams value most:
- Strong enough to support wet concrete loads
- Lightweight and easy to handle on-site
- Simple to cut, place and secure
- Designed to collapse after curing, allowing soil movement
- Cleaner sites and easier disposal
Honeycomb board delivers reliable performance without adding complexity to the pour.
BUY HONEYCOMB VOID FORMER, READY FOR SITE
To make ordering easier for builders and formwork contractors, Rebul offers standard honeycomb void former sizes available to purchase online, no quoting delays for common slab requirements.
All products are:
- Bagged and site-ready
- Lightweight and easy to handle
- Available for fast delivery Australia-wide
Order void formers online for fast site delivery.
Rebul Void Formers
CHOOSING THE RIGHT VOID FORMER THICKNESS
Selecting the correct thickness is critical to slab performance and compliance.
Common options used across Australian builds:
- 50mm – Residential slabs and light commercial projects
- 75mm – Mixed-use and standard commercial slabs
- 100mm – Higher load slabs and highly reactive soils
Any thickness greater than 100mm can be achieved by bonding boards together to meet engineered requirements.
Standard board size:
2400mm × 1200mm
Thicknesses available: 50, 75, 100mm
Need custom thicknesses or quantities?
REBUL VOID FORMERS: MANUFACTURED FOR AUSTRALIAN CONDITIONS

Rebul manufactures honeycomb void formers specifically for the Australian construction industry.
With over 20 years of experience in honeycomb board manufacturing across Melbourne, Sydney and Brisbane, Rebul delivers:
- Fast delivery Australia wide
- Consistent quality and load strength
- Lightweight and easy to handle on site
- Reliable supply for staged pours
- Local manufacturing with fast turnaround
- Made from recyclable material
- Increased cost saving
Builders and formwork companies choose Rebul for reliability, not just price.
APPLICATIONS, SUSTAINABILITY & DELIVERY, BUILT FOR REAL-WORLD CONSTRUCTION
Rebul honeycomb void formers are used across a wide range of construction environments, from residential slabs through to large-scale commercial and infrastructure projects. Their high strength-to-weight ratio makes them easy to handle on-site while still providing the load support required during concrete pours.
For formwork contractors and builders, this means one solution that works across multiple job types, whether you’re managing a single residential slab or coordinating staged pours on a large development.
Rebul void formers are commonly specified for:
- Commercial buildings
- Residential developments
- Infrastructure and civil works
- Projects operating in reactive soil conditions
Because the boards are lightweight and consistent in size and performance, they integrate easily into existing formwork systems without slowing down install times.
A PRACTICAL, SUSTAINABLE SOLUTION THAT DOESN’T SLOW THE JOB DOWN


Rebul honeycomb void formers are manufactured from recycled materials and are fully biodegradable and recyclable. Unlike polystyrene alternatives, they break down naturally after curing, reducing waste handling and disposal requirements while supporting modern sustainability targets.
Just as importantly, they are manufactured in Australia, allowing Rebul to maintain consistent quality control and reliable supply. This local manufacturing capability supports fast turnaround times and delivery direct to site, helping formwork companies avoid delays that can impact pour schedules and project timelines.
FROM SPECIFICATION TO SITE, A SIMPLE PROCESS
Getting the right void former shouldn’t be complicated.
Rebul’s process is designed to support builders and formwork teams from specification through to delivery:
- Share your project requirements and slab details
- Receive expert guidance on thickness and quantities
- Confirm your order, standard or custom
- Get fast delivery direct to site, Australia-wide
Need void formers delivered to site fast?
READY TO SOURCE VOID FORMERS FOR YOUR NEXT POUR?
If you’re a formwork contractor, concreter or builder working on reactive soils, choosing the right void former is critical to slab performance, site efficiency and long-term structural outcomes.
Rebul manufactures honeycomb void formers specifically for Australian construction conditions, with proven strength, consistent quality and reliable delivery when your project schedule demands it.
Whether you need standard 50mm, 75mm or 100mm void formers for an upcoming slab, or a customised solution to meet engineering requirements across staged pours, our team can help you specify the right product and get it to site on time.
You can order standard void formers online for fast delivery, or speak directly with our specialists to discuss quantities, custom thicknesses or bulk supply.
