Void filling The process of filling empty air pockets or washed-out cavities beneath a concrete slab to restore structural support and prevent settling.
Soil erosion, water leaks, or burrowing pests can wash away the subbase under an NYC sidewalk, leaving a dangerous hollow void. If left unaddressed, the concrete flag will crack or collapse under heavy foot traffic. Void filling stabilizes the area, but if the sidewalk has already cracked or shifted, the property owner must replace the damaged concrete to comply with DOT standards.
Frequently Asked Questions About Void filling
What is void filling?
Filling empty pockets or washed-out cavities beneath a concrete slab to restore support and prevent further settlement.
What creates voids under a sidewalk?
Soil erosion, water leaks, poorly compacted backfill and, occasionally, burrowing animals.
Does void filling fix a cracked flag?
No. It stabilizes the support, but a flag that has already cracked or shifted still has to be replaced to comply with DOT standards.
Why address voids before repouring?
Because new concrete placed over an unsupported area will crack the same way the old slab did.