Lightweight material used to create voids under concrete slabs to prevent soil contact and allow for ground movement.

Void Form is lightweight material used to create voids under concrete slabs to prevent soil contact and allow for ground movement through disposable forms that create controlled empty spaces beneath concrete structures while providing temporary support during concrete placement and curing. This essential concrete construction product consists of corrugated cardboard, plastic, or foam materials shaped into boxes or forms that are placed on grade before concrete pouring, creating permanent voids that eliminate direct soil contact and accommodate ground settlement or heave. Void forms are critical components in concrete construction where they prevent slab cracking from soil movement, reduce concrete volume, provide insulation benefits, and enable proper drainage, making them indispensable for slab-on-grade construction, foundation work, and any concrete application where soil movement, thermal isolation, or material savings are necessary for structural performance and longevity.

Void forms are utilized in various concrete construction applications and foundation systems including residential slab-on-grade construction where they prevent soil contact and accommodate ground movement, commercial building foundations where they provide uniform support and reduce concrete requirements, industrial facilities where they handle heavy loads while managing soil conditions, parking structures where they create drainage space and reduce structural weight, sidewalks and flatwork where they prevent cracking from freeze-thaw cycles, and specialty applications including bridge approaches, retaining wall backfill, and utility installations where controlled voids are necessary for performance and maintenance access. Each application requires appropriate void form sizing, placement, and installation methods based on load requirements and soil conditions.

The types and materials of void forms include corrugated cardboard forms that provide economical solutions for standard applications, plastic forms that offer enhanced durability and moisture resistance, foam forms that provide insulation benefits along with void creation, rectangular boxes that create uniform void spaces for typical applications, round forms that accommodate pipe installations and drainage systems, and custom shapes that address specific architectural or engineering requirements. Material selection depends on environmental conditions, load requirements, and performance specifications.

Fun Fact: Void forms can reduce concrete volume by up to 30% in some applications, and the concept dates back to ancient Roman construction where pottery vessels were used to create voids in concrete vaults to reduce weight.

• Form Oil
• Form Tie
• Insulated Concrete Form (ICF)