1. Select the right formwork. Formwork, the temporary or permanent molds used to hold fresh concrete as it sets, are a crucial element in concrete construction. The selection of formwork greatly affects the schedule, labor requirements, quality, and total cost of a project. Because conditions vary at each jobsite, there is no simple formula for choosing the right system or supplier. Formwork typically accounts for 40% to 60% of the total cost of a building's structural concrete frame. These percentages include the costs of material and labor. The largest portion of these cost comes from labor, so it is important to analyze labor costs thoroughly; reducing them will have a much greater impact on bottom line costs.
To help determine the most efficient option for a project, a contractor should evaluate several forming systems. There are two choices: an inexpensive forming material that is labor-intensive, or a forming system that costs more, but provides high productivity, has built-in safety features, and is more labor efficient. Other questions the contractor should consider when choosing a formwork system include:
- Is the material required readily available? Does the supplier manufacture the material or does it purchase it from another company?
- Can the formwork supplier pre-assemble some or all of the formwork prior to delivery?
- Does the supplier provide onsite field service to train 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?
2. Get involved early. Contact formwork suppliers during the early design stage of the project. This allows for as much information as possible to be incorporated into the bid documents, which will provide a more accurate cost for the owner. Formwork suppliers can advise on sizing structural concrete members to meet standard form dimensions. 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 the right formwork system for a project. It also is important to ask concrete forming contractors to be involved early in the design stage of the structure. Because they ultimately build the structure, they can provide a tremendous amount of knowledge as to the most economical formwork means and methods.
3. Know when to purchase and when to rent. Another consideration is whether to purchase or rent a formwork system. This decision should be based on the duration of the project and the overall strategy of the company. Typically, if a form system is rented for more than 8 to 10 months, purchasing the system may prove more economical. However, with the purchase of a system, additional costs can incur, such as maintenance and storage.
Some formwork companies offer these 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 its lifetime than hot-dipped galvanized steel frames with plywood specially manufactured for longer life.
4. Ensure proper access. Proper access is an important component of formwork use at a worksite because it affects the schedule, budget, and safety. Workers must be able to get to the work area using safe horizontal- and vertical-access routes. Ladder systems are designed as integral parts of the overall formwork system to allow safe access to various points on the formwork.
5. Make fall protection the top priority. Falls are one of the top killers at construction sites every year, so fall protection is a major safety concern. For a construction worker, feeling safe is as important as actually being safe. It is important for productivity and peace of mind that workers have a feeling of security as they move about the formwork structure. Workers will perform their duties more productively if they are comfortable with the structure under their feet. If they are working on top of something that feels rickety, they don't feel as confident, and that can result in a loss of productivity.
A formwork structure should be outfitted with equipment that meets OSHA requirements for fall protection. Furthermore, a worker needs a safe, easy way to climb from one area to the next. It is important to have proper ladders installed for easy, safe access on the formwork. On platforms where people will be working, install secure guardrails to protect workers from falls.
One recent innovation that is improving fall protection procedures on high-rise structures is protection screens, which fully enclose a building's slab edge, providing a contained, safe, and more productive working environment. These systems anchor to a slab edge around the perimeter of the building and are used on the upper floors of high-rise buildings as they are erected, providing protection from wind, weather, and the fear of falling. Other safety precaution ideas include good guardrails and toe boards, and good, solid anchorages where workers can tie-off using their own personal fall arrest systems.
6. Ensure accurate handling and proper assembly. One of the common mistakes that contractors make at a jobsite is not following the engineering drawings for assembling and setting up formwork. Not following setup instructions can lead to accidents and trying to save time could result in unsafe working conditions and unnecessary downtime.
When setting up and dismantling a formwork structure, follow instructions carefully to ensure safety. Properly installed ties will hold the formwork firmly in place while the concrete is poured. The formwork must be properly supported before removal of the ties and the formwork from the set concrete.
Another jobsite innovation that reduces jobsite crane time and formwork labor requirements is formwork lifting elevators that mount to the exterior of a building, allowing all formwork to be cycled from floor to floor without a crane. These table lifting systems are used in conjunction with the smaller table method and also allow for other construction materials, including handset shoring, vertical formwork, and reshores from below to cycle from floor to floor without a crane.
7. Don't overlook proper formwork ties. It is necessary to have the proper ties in place to secure the formwork. Having the proper ties in place and not exceeding the maximum pour pressure as per the design not only guarantees safety, but also ensures that the work is done correctly. For example, if you pour the concrete in too fast and the ties are not strong enough, it creates excess pressure on the forms. The ties can fail and the formwork can move, creating an unsafe condition and work that must be redone.
8. Select the optimal assembly method for your project. Having the formwork pre-assembled at the supplier's shop not only can save you time in the field, but also provides many safety advantages. Unlike the often crowded, cluttered construction site, a shop will have clean, smooth, level areas for building the formwork. This allows the formwork to be more accurately assembled, more solidly built, and be aligned better—important aspects for safe construction and use. Pre-assembly at the shop also gives the supplier access to all the safety devices necessary for the formwork structure, such as guardrails and trap doors, and ensures that they will be properly installed. A contractor should expect the formwork supplier to have all the necessary safety equipment included in the system design and in the bid.
9. Safety first. Every worker at a construction site knows about safe practices. Contractors learn safe practices during their apprenticeships, and several trade organizations promote the safe and proper use of forming and shoring equipment. Safety is never a simple matter, but if safety equipment features are easy to use then workers will be more likely to use them.
The purpose of safe practices is so that all workers have a common level of knowledge and they will all do things the same safe way. If everyone at a construction site follows the same set of safety rules, then a worker on one side of a formwork structure can be confident that a worker on the other side is doing the same thing. For a contractor, enforcing safety at a worksite is the most crucial aspect of getting a job done. With everyone following safe practices, not only will there be fewer accidents (or no accidents at all) but also benefits in increased productivity and efficiency.
10. Training: Formwork technology is changing constantly, and you should take advantage of the training now being offered on the proper and safe use of forming equipment by the equipment suppliers. Many companies offer training sessions, which are a mixture of classroom and hands on learning, for its products. An excellent way to boost your workforce's productivity is to have them attend these training sessions. CC
Michael Schaeffer is senior U.S. product manager for Doka USA Ltd. Visit www.doka.com for more information.