Where’s the job?

Scope of Works

• Inspect slab and surrounding area to locate voids and identify access points

• mark and map injection locations and check for underground services

• drill small-diameter holes through the concrete and install packers or ports

• pump cementitious grout or low-density expanding foam into voids and monitor volumes and slab movement

• make good drill holes, clean the area and remove spoil; provide before/after photos and a basic completion report

• use dust suppression, PPE and contain any contaminated runoff during works

Typical Cost

Time on Site

Most small residential slab fills take 3–8 hours on site; larger jobs with multiple voids or restricted access can take 1–2 days. Time is extended by difficult access for pumps, locating services, multiple injection points, long set times for some materials and any required traffic management

Questions to Ask Your Tradie

• how many slab-filling jobs like this have you completed and can you show references or photos

• which method will you use (cementitious grout or expanding foam) and why is it suitable here

• how will you locate and protect underground services and can you supply a risk assessment

• what guarantees or warranty do you provide for the fill and any slab movement

• do you carry public liability insurance and can you provide certificates before work starts

• how long before the area can be trafficked and will you provide a written report and photos on completion

How to Avoid Surprises

• ensure clear access and parking for a pump vehicle or delivery and confirm any permit requirements

• disclose known underground services, drains or voiding history before the visit

• remove or protect floor coverings and furniture around the work area and clear a working zone

• agree the material type, health and safety measures, waste disposal and any warranty in writing before work starts

• check for any building-control or highways permits needed for external or kerbside works