Question: How can I make sure I’m getting the most longevity and use from my concrete forms?
Answer: We asked Roger Roatch with APA - the Engineered Wood Association, to respond:
When it comes to concrete structures, formwork may represent close to half the cost. Fortunately, concrete forms are durable workhorses that can be used over and over with proper maintenance and upkeep. Here are seven ways to extend the life and usefulness of your plywood concrete forms:
1. Strip forms carefully. Metal bars or pry bars should not be used on plywood because they will damage the panel surface and edge. Instead, use wood wedges, tapping gradually when necessary.
2. Clean and apply release agents. Soon after removal, plywood forms should be inspected for wear, cleaned, and repaired, spot-primed, refinished, and lightly treated with a form-release agent before reusing. Use a hardwood wedge and a stiff fiber brush for cleaning. Avoid using a metal brush because it may cause wood fibers to “wool.”
3. Apply sealants and release agents as directed. Protective sealant coatings and release agents for plywood increase form life and aid in stripping. Some panels may require only a light coating between uses. Applying a form release agent a few days before the plywood is used, then wiped so a thin film remains, will prolong the plywood’s life, increase release characteristics, and minimize staining.
4. Know the difference between release agents and coatings. Release agents and coatings can affect forms and concrete differently, so select a release agent keeping mind its influence on the finished concrete surface. For example, some release agents including waxes or silicones should not be used where the concrete is to be painted.
Plywood form coatings, such as lacquers, resin, or plastic base compounds sometimes are used to form a hard, dry, water-resistant film on plywood forms. Usually, the field-applied coatings reduce the need for application of release agents between pours and result in greater reuse.
5. Patch and repair forms. On prefabricated forms, plywood panel faces (when the grade is suitable) may be reversed if damaged. Tie holes may be patched with metal plates, plugs, or plastic materials. Nails should be removed and holes filled with patching plaster, plastic wood, or other materials.
6. Handle and store forms properly. Be carful to prevent panel chipping, denting, and corner damage during handling. Panels should never be dropped. Forms should be carefully piled flat, face to face and back to back. Forms should be cleaned immediately after stripping and can be solid-stacked or stacked in small packages with faces together.
Hairline cracks or splits may occur in the face ply. These “checks” may be more pronounced after repeated use of the form. Checks do not mean the plywood is delaminating. Form maintenance, including careful storage to assure slow drying, will minimize face checking.
7. Consider the effects of admixtures and chemicals. Many admixtures and pozzolans increase the abrasiveness or alkalinity of the concrete. While wood and phenolic overlays resist alkaline solutions and abrasion, some admixtures may significantly decrease the lifespan of a concrete-forming panel.
There’s much to consider when it comes to proper upkeep and maintenance of concrete forms. But following these tips will ensure the best life and use of forms project after project.
Roger Roatch is an Engineered Wood Specialist for APA. For more on concrete form maintenance and selecting the best form panel for the project, download the APA Concrete Forming Design/Construction Guide here.