One of the most common questions from Wagga Wagga homeowners facing underpinning is simply: how long will this take, and will I be able to stay in my home? It is a practical question, people have work, children, routines, and limited appetite for disruption. The answer depends on the underpinning method, the size of the project, the subsoil conditions, and the scope of follow-on work. This guide gives you realistic timelines for each scenario. Our separate guide on how long underpinning takes provides a complementary overview, this guide focuses specifically on the step-by-step process from start to sign-off.
Quick answer (BLUF)
Most residential underpinning projects in Wagga Wagga take 3-10 working days on site. Mass concrete underpinning is 5-10 days for a typical home. Screw pier underpinning is 1-4 days for a standard residential project. Resin injection is 1-2 days. Add 1-4 weeks at each end for the inspection and quote process, and allow additional time for curing, follow-on crack repairs, and any engineering sign-off.
Phase 1: Inspection and assessment (1-3 weeks)
Before any underpinning can begin, the problem must be properly diagnosed. A foundation inspection, whether by a structural engineer or experienced building inspector, typically takes one to two hours on site. The written report is generally delivered within three to five business days.
If the inspection identifies that a full engineering design is required (common for larger or more complex projects), a structural engineer must prepare the underpinning design. This adds one to three weeks depending on engineer availability and project complexity.
For straightforward residential jobs on typical Wagga soil, some contractors work from an experienced builder’s assessment rather than a full engineering design. However, for insurance claims, council requirements, or complex situations, an engineering design is preferable.
Total for Phase 1: 1-3 weeks.
Phase 2: Quotation and scheduling (1-4 weeks)
Once the scope of work is understood, quotes are obtained from contractors. In Wagga Wagga, lead times for reputable underpinning contractors can be 2-6 weeks, particularly in the busy autumn period (when summer cracking becomes apparent) and spring period (when owners address winter heave issues).
Allow two weeks minimum for the quote-compare-decide process, and a further 1-4 weeks for contractor scheduling.
Total for Phase 2: 1-4 weeks from inspection.
Phase 3: On-site works, by method
Mass concrete underpinning
Mass concrete underpinning involves excavating a series of pits beneath the existing footing, in an alternating sequence (every second pit excavated first, concreted, then the intermediate pits), and filling each pit with concrete that bonds to the underside of the existing footing.
The alternating sequence prevents simultaneous removal of support from adjacent footing sections. Each pit must cure before the adjacent pit is excavated. This sequence drives the timeline:
- Day 1-2: Set up, mark out, excavate Sequence 1 pits
- Day 2-3: Pour concrete into Sequence 1 pits
- Day 3-5: Curing time for Sequence 1 concrete (typically 48-72 hours)
- Day 5-7: Excavate Sequence 2 pits
- Day 7-8: Pour concrete into Sequence 2 pits
- Day 8-10: Final curing and clean-up
For a typical Wagga home with 10-15 underpinning pits, the on-site work takes approximately 5-8 working days.
Screw pier (helical pile) underpinning
Screw piers are installed by rotating the pier into the ground using hydraulic equipment, bypassing the reactive clay zone and bearing on stable material below. No excavation is required and no concrete needs to cure.
The installation process for a typical residential project is fast:
- Day 1: Set up hydraulic equipment, install all piers in sequence (usually 6-15 piers for a residential job)
- Day 1-2: Attach bracket system to existing footing
- Day 2: Lift structure to design level (lifting is done gradually across all piers simultaneously)
- Day 2-3: Final checks, levelling confirmation, sign-off
Screw pier underpinning for a standard Wagga home typically takes 1-3 working days on site.
Resin injection (polyurethane foam lifting)
Resin injection involves drilling small-diameter holes through the slab or adjacent to the footing and injecting expanding polyurethane resin. The process is very quick, most residential jobs are completed in a single day.
Resin injection is most applicable for minor slab lifting and soil compaction on relatively flat sites. It is not the appropriate solution for all foundation problems and is less suitable for heavily reactive clay sites where ongoing movement is expected.
Phase 4: Follow-on works (2-8 weeks)
After underpinning, a period of monitoring is typically recommended before cosmetic repairs are made. On Wagga’s reactive clay, some residual movement may occur as soils adjust to the changed load distribution. Most contractors recommend waiting four to eight weeks before crack repairs and repainting.
Crack repairs themselves take one to two days for a typical home. Plastering, painting, and making good is additional.
If an engineering sign-off certificate is required (for insurance or council purposes), allow one to two weeks for the engineer to attend site, review the works, and issue certification.
Can you stay in the house during underpinning?
For most underpinning projects in Wagga Wagga, the answer is yes. The subfloor works are below the living space and access is limited to the subfloor via access hatches. For mass concrete underpinning, some noise and vibration accompanies excavation. For screw pier installation, the equipment operates outside the home.
In most cases, homeowners can occupy the property throughout the works. If the project requires significant excavation adjacent to a wall or lifting of a slab with occupied rooms above, a temporary precautionary relocation may be advisable, your contractor will advise.
FAQs
What takes longer, underpinning or restumping?
Restumping a typical Wagga home takes 3-7 working days on site, similar to mass concrete underpinning. Screw pier underpinning is generally faster than restumping for the same number of support points. The overall project timeline from first call to completion is similar for both: typically 4-8 weeks including inspection, quoting, and scheduling.
Will the floors be perfectly level immediately after underpinning?
Not necessarily. On reactive clay, some residual adjustment occurs after underpinning as soils stabilise. Most contractors target the floor being within 10 mm of design level immediately after completion, with the expectation that it will continue to improve slightly. A follow-up check at three to six months is standard practice.
Does underpinning require council approval in Wagga Wagga?
In most cases for residential underpinning, works are considered exempt under the NSW Exempt Development Code, provided they are within the existing footprint and do not alter the building structure above. Check with Wagga Wagga City Council if your property is heritage listed or in a heritage conservation area, as additional requirements may apply.