Basement Floor Void Fill

Basement Floor Void Filling–Foam Jacking, Herndon, Virginia


Backfill material below basement floor slab settled. As a result of the backfill material settlement, the floor developed extensive cracks due to inadequate support, but had not started to settle. The owner of the home was concerned about potential settlement of the slab given the extensive cracking and hollow “thumping” sound when tapping on the floor.


The customer was preparing to install new flooring in their home, so wanted a repair which would be fast, and also economical, as this was an unexpected expense. Given the instability of the underlying soil, a lightweight material which wouldn’t add a lot of extra weight to the underlying soil was needed. There were also load-bearing structural columns which rested on the affected areas of the slab, so while being lightweight, the void material had to be strong enough to permanently support the foundation elements.


High density polyurethane foam jacking to fill the voids below the basement floor concrete slab. Foam jacking injects material through small (dime-size) holes drilled through the concrete. Because the holes are small and can easily be patched with fast-setting grout, they don’t delay flooring installation.


Concrete Jack foam jacking crew stabilized the slab and structural loads resting on the slab in a few hours. The foam used on this slab foundation repair project cures in a few seconds, so the customer was able to continue using the area as usual.