Reducing the cost of formwork construction is essential for keeping total project costs low. Decisions made at the design phase, such as using new materials, accessories, and prefabricated formwork components, can help achieve design goals with fewer costs. Additionally, following the recommendations of the Concrete Reinforcing Steel Institute, such as using one form scheme throughout the project, orienting all framing in one direction, using standard form sizes, and employing the same level for all beams and joists, can help to reduce the cost of formwork construction.
Reducing the Cost of Formwork Construction
Formwork is an integral part of the concrete structure and construction process, but it can also be the most expensive. It accounts for up to 60% of the total cost of a concrete project, making it essential to consider how to reduce formwork costs. There are several decisions at the design phase that can help to reduce costs, such as using new materials, accessories, and prefabricated formwork components.
The Concrete Reinforcing Steel Institute (CRSI) offers several recommendations for achieving economy in formwork costs. These include using one form scheme throughout the project, orienting all framing in one direction, using standard form sizes, and employing the same level for all beams and joists.
Using New Materials and Accessories
Finding ways to reduce the cost of formwork construction begins at the design phase. Utilizing new materials, accessories, and prefabricated formwork components can help achieve design goals with fewer costs.
For instance, materials such as steel, aluminium and plastic are more lightweight and durable than traditional lumber, and they offer a range of shapes and sizes to fit any project. Additionally, prefabricated formwork components can be used to reduce labour costs and improve the speed and accuracy of construction.
CRSI Recommendations
The CRSI has developed several recommendations to help reduce the cost of formwork construction. These include using one form scheme throughout the project, orienting all framing in one direction, using standard form sizes, and employing the same level for all beams and joists.
Using a single form scheme throughout the project helps to reduce the amount of time and labour required for formwork construction. Additionally, orienting all framing in one direction can save time, as it eliminates the need to reverse direction. Standard form sizes and employing the same level for all beams and joists also help to reduce labour costs.
How to Achieve Economy in the Cost of Formwork Construction?
Using a Single Framing Scheme
To reduce mobilization and formwork material costs, as well as improve labor learning, it is recommended to use a single framing scheme for the entire project. This would be preferable to using two framing schemes, which is only justifiable on large projects. To reduce costs even further, beams and joists should be of the same depth, with reinforcement ratios adjusted to resist the load.
Spacing and Sizing Columns
To simplify forming and save money, columns should be spaced uniformly and of the same size, as well as joists and beams. It is recommended to maintain a constant floor-to-floor height, although reductions can be made in upper storeys to cut costs and save time. Small drop panels should be used instead of tapered columns in flat plates in order to reduce forming costs. The height of drop panels should be chosen to fit standard lumber dimensions.
Framing Orientation and Form Sizes
In one-way system construction, all framing should be oriented in the same direction for the sake of time and cost-efficiency. Standard form sizes should be used for both one-way joists and two-way domes to avoid additional fabrication charges. The capacity of minimum-sized members should be maximized by arranging form member sizes and spacing accordingly. Slabs should have a thickness of at least 200 cm and span as far as the minimum reinforcement will allow.
Flat Plate Consideration
For spans up to 7.6m, it is recommended to use a flat plate since it is comparably cheaper, faster, and shallower. Tolerances should be kept to a reasonable level, with strict tolerances only applied in locations where absolutely necessary. Forms should be stripped after a certain time limit for walls and columns, and when the design strength has been reached for beams and slabs. It may also be necessary to employ reshoring until the design strength is achieved to prevent excessive deflection.