A Guide to Off-Form Concrete Construction in Sydney

The Foundation for Buildings in Sydney

These days most buildings in Sydney have a component made up of concrete whether it's the exterior facade or a structural element. Concrete is a durable and cost-effective material that is popular in all aspects of building.

What we have been able to do with the finished look of concrete particularly in external facades around Sydney can be largely attributed to the preferred use of off-form concrete.

What is Off-Form Concrete?

Off-form concrete occurs when concrete is poured into a mould while it is still soft (before it sets) and removed to reveal a ‘finished’ surface, with repeated placement of steel reinforcement. Off-form concrete creates unique textures and patterns that give each structure its own character. 

Off-form Concrete in the Sydney Scene

Off-form concrete is increasingly becoming a preferred finish in Sydney. The versatility and durability of off-form concrete means it is finding its way into an increasing number of residential and commercial developments. 

Advantages of Off-Form Concrete

Durability of Off-Form Concrete

Off-form concrete is a proven and resilient material. It does not wear easily, and its strength and solidity provide its structural permanence. The structural properties of off-form concrete could play a significant role in the foundation and facade of buildings. The durability of off-form concrete is enhanced by its water resistance and its thermal mass, a combination that allows off-form concrete to hold up well in extreme weather conditions and under environmental pressures.

Aesthetics of Off-Form Concrete

The industrial look of off-form concrete creates an aesthetic appeal in its roughness and concrete-y nature. The visual impact of off-form concrete endures but can be subtle with smooth finishes or harsh with more textured effects; the choice is entirely up to the architect or designer. Off-form concrete can be cast into virtually any shape or form, be it minimal, curvy or prismatic.

Low Maintenance of Off-Form Concrete

One of the major benefits of off-form concrete is its low maintenance once it is sealed. The upkeep of off-form concrete over the lifetime of the product is extremely low cost. The nature of the material means that off-form concrete doesn’t need to be regularly repaired or resurfaced to maintain its look and keep it standing in the long term. 

Regular cleaning and visual checks for unseen damage are usually sufficient to maintain off-form concrete.

Innovations in Off-Form Concrete

Off-form concrete is a game-changer for the Sydney construction industry, where it is revolutionising building standards with bespoke concrete designs and Class 1 finishes. 

Choosing the Right Off-Form Concrete Contractor

If you need results of high-quality off-form concrete in Sydney, you should choose a contractor carefully. Choose an off-form concrete contractor with experience, expertise and a portfolio of work completed on time and as agreed. 

Such features make off-form concrete an ideal material for much of Sydney’s buildings, providing the practical and pleasing shape of a new and innovative material that complements civic architecture. 

 •   Hydraulic Cement - The main binder in off-form concrete and the glue that sets concrete hard over time.

 •  Water - Necessary for the chemical reaction with cement that allows the off-form concrete to set and harden.

•  Aggregates - Typically sand, gravel, or crushed stone, aggregates give the off-form concrete structure and bulk.

 •  Admixtures - Chemical additives added to the off-form concrete to increase either workability or durability or to alter the setting time.

 • Reinforcement - Sometimes, the off-form concrete is given more strength by placing steel bars or mesh inside.

 •  Formwork - Temporary (or permanent) moulds into which the off-form concrete is poured. The formwork is the shape and surface of the final concrete member.

There is no need for reinforcement or steelwork, nor for shuttering of off-form concrete; the formwork is sufficiently rigid to cope with the pressure exerted by the fluid concrete and is removed after setting (usually within 24 hours), 

Top and bottom surfaces of off-form concrete can be exposed to the elements without special waterproofing. This method is suitable for walls, where there is a lesser demand for strength than precast concrete. 

In addition, hollow sections of off-form concrete are easy to form for window or door openings without the need for these being ‘cut and shuttered’ on site.

The Finished Look of Off-Form Concrete

This is an off-form concrete finish. It can go from coarse and rough (Class 2 finish) to very smooth and polished, depending on what the final appearance of the off-form concrete is meant to be. 

Off-form concrete has a minimum thickness of 15 centimetres (6 inches), but the walls are likely to be higher; walls built using this method have reached heights of many meters, and sometimes multi-storey buildings have been built with massive long curtain walls from a single formwork wall system.

Off-form concrete in 2024 is still highly popular for its aesthetic flexibility, structural strength, and cost-efficiency in building applications.

Summary

Off-form concrete construction in Sydney is not merely vital in the city's construction field. It is a reflection of the city’s commitment to avant-garde and sustainable architectural practices. Off-form concrete will continue to be a prominent feature of Sydney as it grows in the years to come.

If you are looking at off-form concrete for your next project, leverage the experience of the LFCS team to guarantee the success of your project.