Steel Formwork Vs Timber Formwork

Steel and wood are the most commonly used formwork materials in construction, each with its merits and drawbacks. Thanks to its long durability and high load capability, steel formwork is specified for large-scale infrastructure projects like high-rise construction and bridges, while wooden formworks are mainly suited to small or medium-sized construction work due to their low cost and ease of handling. Several criteria must be considered to allow informed judgment when selecting the formwork system. Factors like budget considerations, time duration of construction, type of construction activity, and expected performance of the formwork all may determine what formwork is to be used in a particular construction project.

This blog is going to compare the advantages and disadvantages of steel formwork and wood formwork, helping builders and designers to make more justifiable decisions based on the specific project needs. Whether it is a high-rise building pursuing efficient construction or a small house with a limited budget, understanding the differences between these two formwork materials becomes essential towards the smoothening of the project.

Definition Of Steel Formwork

Steel Formwork is that type of system made of steel onto which concrete structures are poured in construction projects. Temporary support is provided to concrete to keep it in the shape and configuration where it pours into the designed structure and size.

Advantages Of Steel Formwork

Less Adsorption And Easier Demoulding

• The smooth surface of the steel formwork makes it easy to demould once the concrete has cured against it, considerably decreasing the intensity of labor and time required for the concrete works. This combination offers low adsorption, allowing for demoulding with the concrete without risking damage from bonding to the concrete surface.

Repairable Construction At The Site

• In the event of any deformation or damage, the strong structure of the field-repairable steel formwork can be repaired on-site without replacing the entire formwork. Repairs do save a lot of costs and time. This is particularly beneficial during the construction of large projects.

Good Life Cycle, Many Reuses

• The reusability of steel formwork is one of the biggest plus points. They are durable and can usually be reused more than 50 times or more under some conditions. Hence, steel formwork is highly suitable for long-term, large-scale projects. Steel formwork will outlive wood over the long run in view of the life cycle and eventually, be more suitable for large long-term projects.

Strong And Can Hold Heavier Weights

• Steel formwork being stronger is capable of enduring bigger concrete pressures, whereby it is specifically more appropriate for construction works that will bear a high dead load. The steel formwork maintains the state of stability of shape and size when concrete is being poured, with that having a guarantee that the quality of the concrete structure is not compromised by any deformation that the formwork might suffer.

Disadvantages Of Steel Formwork

Costly

• Steel formwork has an expensive initial purchasing cost that can lead to very heavy financial burden, especially on smaller projects. Though steel formwork could generate long-term economic benefits, its enormous purchasing and maintenance costs can seriously damage smaller projects having limited funds.  

Limited Shapes Or Dimensions

• In occasions in which projects demand customized or intricate designs, steel formwork has reduced flexibility. So on certain non-standard projects, steel formwork may not be as flexible as timber formwork.  

Smooth Surface Affects Finishing

• Since steel formwork has an extremely smooth surface, it makes demoulding a breeze, yet it can spoil the impression of roughness and surface treatment for the concrete. For concrete surfaces where a roughened or specific texture is necessary, supplementary finishing, such as plastering or grinding, may be required for the concrete quality to achieve the required criterion.  

Enhanced Heat Loss

• Heat loss during the concrete curing stage will be high in steel formwork, which will in certain cases adversely influence projects that need to have certain temperature conditions. For instance, due to the high thermal conductivity of steel formwork, in an environment that is cold, concrete will cool too rapidly, thus affecting strength and quality of curing.

Definition Of Wooden Formwork

Wood formwork is a mold system made of wood or wood products used in construction projects for pouring concrete structures. It provides a temporary structure to support and shape concrete so that it can be poured into the designed shape and size.

Advantages Of Wooden Formwork

Easy Processing And High Flexibility

• One of the biggest advantages of wooden formwork is its high processing flexibility. Wood can be easily cut and shaped according to the project requirements and is suitable for concrete structures of various shapes and sizes. This makes wooden formwork an ideal choice for construction projects with special design requirements, complex geometries or non-standard dimensions.

Low Cost And Easy To Purchase

• Wood formwork has a relatively low initial investment, making it the first choice for many small projects with limited budgets. Wood formwork is not only easy to purchase, but also much cheaper than steel formwork. Therefore, wood formwork is an ideal choice for small-scale construction projects that need to control costs.

Convenient And Lightweight Construction

• The wooden formwork is light in weight, making it easier to carry and install. For small projects that require frequent replacement of formwork, the lightness of the wooden formwork greatly improves construction efficiency. In addition, the disassembly and storage of the wooden formwork is relatively easy, making it particularly suitable for small and medium-sized construction projects.

High Thermal Elasticity, Adaptable To Cold Climates

• Wood itself has high thermal elasticity, which makes wooden formwork particularly advantageous in cold climates. Wooden formwork can effectively prevent concrete from solidifying quickly in a low temperature environment, avoiding quality problems such as concrete cracks caused by excessive temperature differences. For some projects in cold areas, wooden formwork is a better choice.

Simple Replacement Of Damaged Formwork

• If the wooden formwork is damaged during use, it can be quickly replaced. On the construction site, workers can usually easily replace the damaged wooden formwork without the need for complicated repair procedures, which also helps to improve the project schedule.

Disadvantages Of Wooden Formwork

Poor Durability And Limited Number Of Uses

• Wooden formwork is not durable and can be reused only 4 to 6 times in practice. Therefore, the long-term economic cycle for large construction projects favors steel formwork over wooden formwork. They have a low service life and must be replaced regularly, thus increasing the cost of long-term use.

Water Absorption Problem

• Wood has a strong ability to absorb water, especially in a humid environment, and wooden formwork easily absorbs moisture from wet concrete. This may cause the wooden formwork to swell or deform, thus affecting the surface quality of the concrete. Especially in rainy seasons or humid environments, the use of wooden formwork may bring additional problems.

Problems Caused By High Moisture Content

• Wooden formwork is susceptible to moisture in a humid environment. When the moisture content is high (more than 20% moisture content), it may cause the concrete surface to shrink or cup, leading to problems such as open joints and mortar leakage. This has an adverse effect on the quality of the concrete and the safety of the structure.

Steel & Timber Formwork Applicable Scenarios

Steel formwork is suitable for

• Large construction projects
• High load, complex structure projects
• Engineering requiring high precision
• Long-term, large-scale construction projects

Wood formwork is suitable for

• Small and medium-sized construction projects
• Projects with complex shapes and custom designs
• Short-term projects
• Small infrastructure projects with limited budgets

Environmental Impact And Sustainability

In Conclusion

Whether to choose steel formwork or wooden formwork should be considered comprehensively based on the project's scale, budget, design requirements, construction period and environmental protection goals. It is also necessary to fully communicate with the supplier to ensure that the quality of the formwork and construction services can meet the specific requirements of the project. Whether to choose steel formwork or wooden formwork, reasonable planning and selection will lay a solid foundation for the smooth implementation of the construction project.

FAQ

Does one formwork system offer a better quality of finish?

• Steel Formwork: Generally produces a smoother, more consistent finish due to its precision and lack of deformation.
• Timber Formwork: Can produce a good finish, especially with high-quality plywood, but might show wood grain or joints if not properly maintained.

Are there any safety concerns specific to either formwork system?

• Steel Formwork: Requires proper training for handling heavy components, and there's a risk of injury from sharp edges or falling parts.
• Timber Formwork: Can be less stable if not properly braced, and there's a risk of splinters or nails. Proper securing and bracing are crucial to prevent collapse.

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