As new innovative products are continually entering the marketplace, learning about them and how they affect the construction process is a continuous process. For example, a fairly new product being used in the construction process on high-rise structures is protection screens. They fully enclose a building’s slab edge, providing a completely contained safe and more productive working environment. These systems anchor to a slab edge around the perimeter of the building. Another example in high-rise structures is the increased use of self-climbing formwork used on cores and shear walls. When these systems are used in the construction process rebar design needs to be considered, as anchoring of the formwork becomes a critical factor.
Selecting the Right Formwork
Because conditions vary for each individual project, there is no simple formula for choosing the right formwork supplier or system. Formwork typically accounts for 40-to-60-percent of the total cost of a building's structural concrete frame. For concrete walls, the cost can be in the 50-to-60-percent range. These percentages include the cost of material and labor, with the largest cost for labor. It is important to analyze labor costs thoroughly, as this is the bigger number and reducing this number will have a much greater impact on bottom line costs.
To help determine the most efficient solution for a project, a contractor will evaluate several forming systems. As available and capable labor shortages continue in the construction marketplace, it has become even more important to select the right forming system. Simply stated, a contractor has two choices: an inexpensive forming material that is labor-intensive or a forming system that while costing more, provides high productivity, built-in safety features and is more labor efficient.
Other factors the contactor will evaluate when choosing a formwork system include:
- Is the material you require readily available? Does the supplier manufacture the material or do they purchase it from another company?
- Can the formwork supplier pre-assemble some or all of the formwork prior to delivery? This can reduce rental cost, save labor requirements and minimize assembly area requirements.
- Does the supplier provide on-site field service to train and reduce the learning curve of the formwork crew?
- How safe is the system to install, use and dismantle? Can the forms easily be climbed and are tie-off points built into the system where required?
- What experience does the firm have with your type of project?
- Does the supplier offer engineering services? Will the supplier provide formwork assembly drawings specifically for the project or only provide general drawings of the system?
Another consideration is whether to purchase or rent a system. This decision should be based on the duration of the project and the overall strategy of the construction company. Typically, if a form system has to be rented for more than 8 to 10-months, purchasing the system might be more economical. However, along with the purchase of a system, there are additional costs such as maintenance and storage. Some formwork companies, however, offer services for customers who purchase their equipment.
The quality of the product also must be considered in the decision-making process. Steel-framed wall formwork with standard plywood facing will require more maintenance and repair throughout the life of the form than hot-dipped galvanized steel frames with specially manufactured plywood designed for longer life.
Forming a Relationship
In order to consider formwork in the overall design, it is important for the structural engineer to have a good handle on the standard products available in the marketplace. This can be accomplished by contacting the major formwork suppliers. They are more than eager to provide assistance to educate the industry on forming products available and how the structure’s design affects overall costs.
Contact formwork suppliers at the very early design stage of the project. This can allow for as much information as possible to be incorporated into the bid documents, which will provide a more accurate cost to the owner. Formwork suppliers can advise on sizing structural concrete members to meet standard form dimensions. And, because major form suppliers typically are involved in a large number of projects in a wide variety of construction markets, they can draw upon their resources to suggest formwork means and methods.
Also of importance is to ask concrete forming contractors to be involved early in the design stage of the structure. They are ultimately the people who will be physically building the structure and can provide a tremendous amount of knowledge as to the most economical means and methods.