Engineered Pier Void Forms for Structural Isolation
Pier void forms are used to isolate the underside of pier caps and pilasters at pier intersections, from expansive soil conditions. This isolation allows protection at these intersections, preventing soil movement from transferring stress into the concrete.
At Carton Forms LLC, our pier void forms are hand-assembled in Denver, Colorado and built with a clear understanding of engineering intent, soil expansion, and real-world jobsite conditions.
When piers are part of the design, proper isolation is critical.
Why Use Pier Void Forms
Piers are designed to transfer load to stable bearing soils. Slabs and grade beams, however, must remain free from applied pressures when expansive soils change volume. Pier void forms provide the separation engineers rely on to make that system work.
Pier void forms are used to:
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Isolate slabs and grade beams at pier top intersections
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Allow independent soil movement between structural elements
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Prevent uplift forces from transferring into concrete slabs and beams
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Reduce cracking, stress, and long-term foundation issues
Without proper isolation, soil movement can compromise the entire structural foundation system.
How Pier Void Forms Work
Pier void forms are placed around the top of the pier when at ground level or if extended, prior to slab or grade beam placement. During the pour, the corrugated carton structure supports wet concrete and reinforcing steel.
After the concrete cures and the structure becomes self-supporting, the pier form gradually weakens from moisture, as designed. As soil expands, it moves into the created void space rather than pushing against the pier intersections.
The result:
Load goes where it’s intended — movement goes where it’s allowed.
Construction & Materials
Carton Forms pier void forms are manufactured using the same proven methods as our slab and wall forms to ensure consistent, predictable performance.
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Wax-coated exterior cover to resist moisture during placement
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Corrugated cellular interior designed to support fresh concrete loads
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Water-based adhesives selected for controlled degradation
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Precision-cut geometry to maintain proper clearance around pier tops
Each form is hand-assembled for consistency and inspected before delivery.
Applications
Pier Forms are commonly used in:
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Slab-on-pier foundation systems
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Grade beam and pier combinations
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Residential structural foundations
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Commercial structural foundations
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Any condition where structural slabs must remain isolated from soil movement.
They are suitable for both residential and commercial foundation systems.
Installation Considerations
Proper installation ensures pier void forms perform as designed. Common best practices include:
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Verify pier diameters and elevations before being manufactured
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Install shaped forms and center around pier tops
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Protect forms from premature compression or damage
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Coordinate placement with reinforcement and formwork
If site conditions or details differ from standard drawings, we’re available to help review and discuss options before the pour.
Compatible With Protection Board and Soil Retainers
Footing void forms are often used in combination with:
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Protection Cover Board to shield forms during reinforcement and concrete placement
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Plastic Soil Retainers to prevent lateral soil movement into the void space
Together, these components help maintain clean, functional void conditions at structural footings.
Why Contractors and Dealers Use Carton Forms Pier Void Forms
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Built to meet engineering specifications
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Designed for predictable isolation performance
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Hand-assembled quality
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Consistent sizing and fit
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Jobsite-aware design
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Technical experience you can lean on
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Reliable delivery and clear communication
Nothing is assumed. Everything is earned.
Availability & Support
Carton Forms pier void forms are available through local concrete supply dealers. If questions come up around specifications, or take-offs, we work alongside our dealers to offer optional product and installation methods, that help ensure the right solution is quoted and supplied.