Concrete Form Maintenance

How To Maintain Wood Forms

Using common framing lumber to form concrete may be the most common method for good reason; it's readily available, relatively inexpensive, and your crew already knows how to work with it. To increase your profit margins, it makes economic sense to reuse these materials as much as possible. Consider the following maintenance tips to get the most longevity from your wood concrete forms.

Remove Carefully – Use caution when taking the forms down after use. Metal or other types of pry bars can damage plywood. The dents in damaged plywood will show up in your next pour. One option is to use wood wedges to gently pry the wood away from the concrete.

Clean After Use – After removing the plywood forms, inspect them for damage and clean them immediately. Make any necessary repairs and clean them with a hardwood wedge or stiff fiber brush (no metal brushes). In preparation for the next use, treat with a forming release agent.

Use Release Agents – Adding a sealant or release agent to the surface increases the lifespan of the wood form. The two most-used types of release agents are barrier-type agents, and chemically active agents. The best method is to apply a release agent, then wipe to leave a thin layer. If done days before pouring the concrete, it provides a barrier to the concrete and prolongs the plywood. It is important to use release agents that are appropriate for the job at hand.

Use Coatings – Coatings affect forms and concrete differently than release agents. When you use a coating, release agents are not needed because the coating covers the plywood effectively. Coatings can be plastic-based, resin, or lacquer and they typically form a hard, water-tight film on plywood.

Consider Chemicals – The more admixtures and chemicals used in the concrete, the more wear and tear the wood forms face. Be aware of what is in the concrete whenever possible and always check the wood for degradation after use.

Fix Forms – Take care of wood forms after use by removing nails and other imbedded objects. Holes should be filled and patched. When using higher grade plywood, both sides can be used; if one side is damaged beyond repair, reverse and use the other side.

Handle with Care – To get the maximum use out of wood forms, store them properly between uses. Avoid dropping and pile them up face-to-face and back-to-back on a flat surface. In general, handle them with care when moving them around.  

Plywood forms won’t last forever, but consistent care and regular maintenance will extend the effectiveness of the forms.

How To Maintain Metal Forms

Taking proper care of metal concrete forms will extend their usability and longevity. If metal forms are used often and only need to be stored for short periods of time, they should be coated with a release agent in between uses. Before storing, the forms should be liberally coated with VOC-compliant petroleum-based solvents. If forms are stored outside, they should be inspected regularly to ensure weather has not affected the release agent coating the forms. If the forms are to be stored for longer periods of time in between jobs, they need to be recoated regularly to be protected effectively. Since they will be coated more often, it is recommended that a biodegradable release agent is utilized. A biodegradable agent ensures that any material that ends up on the ground will not act as a contaminant.

With metal forms, there is the potential for rust, particularly when storing forms outside for long periods of time. Using a rust inhibitor on the forms slows down the rust damage. Rust inhibitors also help displace any water that accumulates on the surface of the form. For increased protection from rust, forms should be inverted when stored so rust does not accumulate, or cover them with plastic to protect the forms from water damage. A more drastic option is to coat the metal forms with a rust preventative. These materials are epoxy-based and go on like paint. However, this coating must be removed before using the forms again, often by grinding. Therefore, using a rust preventative is a long-term storage solution that is only needed under certain circumstances.