Building a new home in Wagga Wagga is exciting, but seeing cracks appear in the walls within the first 12 months is alarming. The good news: some movement is entirely expected, and in many cases normal, for new homes on reactive clay. The challenge is distinguishing normal first-year settlement from something that needs to be fixed.
This guide explains what is expected, what the building code requires, and what signs should prompt you to contact your builder or a foundation specialist.
Why New Homes Move in the First Year
The Soil Disturbance Effect
When a new home is built, the construction process disturbs the soil. Excavation for footings, vehicle traffic across the site, and removal of topsoil all change the moisture regime around the foundation. The clay that was in equilibrium before construction starts a new moisture cycle once it is exposed, covered, or loaded.
In the Riverina’s reactive clay, the first one to two seasons after construction can involve significant soil moisture redistribution as the clay around the new foundation seeks a new equilibrium. This generates small amounts of movement, typically vertical, and often differential.
Slab Drying and Concrete Shrinkage
A concrete slab or foundation poured on site contains a large volume of water that evaporates as the concrete cures. This drying process generates micro-cracking in the concrete, particularly at stress concentration points. Hairline cracks appearing within weeks of the slab pour are almost always related to concrete shrinkage, not foundation movement.
Moisture Redistribution Under the Slab
Before construction, the soil under a new home site was open to rainfall. After the slab is poured, rainfall can no longer reach the enclosed soil. The covered soil gradually dries compared to perimeter soil that still receives rainfall. This moisture gradient between the enclosed and perimeter zones can cause the edges of the slab to rise slightly relative to the centre (edge lift on reactive clay sites), or in drought years, the perimeter to shrink relative to the covered zone (edge fall).
Building Load Consolidation
As the structure is built, roof tiling, brickwork, furnishings, occupants, it loads the foundation. The clay and fill beneath consolidates under this load. In areas with loosely compacted fill or variable clay profiles (such as new estates at Estella and Gobbagombalin), some consolidation settlement during the first year is expected.
What AS 2870 Allows and Requires
Australian Standard AS 2870 (Residential Slabs and Footings) governs the design of new residential foundations on reactive clay in Wagga Wagga. It requires:
- Soil classification testing to determine the site’s reactivity class
- A footing system designed specifically for that reactivity class
- Documentation of the design footing solution
The standard does not eliminate movement, it designs foundations that can accommodate the expected movement within limits that keep the structure serviceable. In practice, this means:
- New homes on properly designed H1 class foundations will still experience some movement
- Hairline cracks in plasterboard and render are expected within the first year
- Slight floor slope variation (up to a few millimetres over 3 m) is within acceptable tolerance
The builder is responsible for delivering a foundation that meets AS 2870 requirements. The foundation performance warranty under the Home Building Act in NSW runs for 6 years (structural defects). Movement outside AS 2870 tolerances in the first 6 years is potentially a defect claim against the builder.
New Estates in Wagga: Specific Issues
Estella
Estella is one of Wagga’s largest newer residential areas, developed primarily from the 2000s. The area includes significant areas of H1 and H2 reactive clay. Homes in Estella built in the early 2000s are now reaching the age (15-25 years) where any initial foundation issues from that period are becoming visible as cumulative movement.
Newer homes in Estella on recently released land have the benefit of more recent AS 2870 design requirements, but site-to-site variation means some lots perform better than others.
Gobbagombalin
Gobbagombalin is developing rapidly on the northern side of Wagga. This is a relatively new suburb and many homes are within their first 5 years. Movement in Gobbagombalin homes during the first year is being reported, not unusually, but homeowners should be aware of what is expected and what is not.
Glenfield Park and Bourkelands
These estates include some areas of H-class clay that were developed in the 1990s and 2000s. Homes here are now 20-30 years old and have been through multiple wet-dry cycles. The initial “settling in” period is long past; ongoing movement in these homes now indicates a progressive foundation issue rather than first-year adjustment.
What to Watch For in Year One
Normal, Monitor But Don’t Panic
| Observation | Likely Cause |
|---|---|
| Hairline plasterboard cracks at wall corners | Plasterboard shrinkage, normal |
| Fine cracks in ceiling cornices | Roof movement, plaster shrinkage |
| Minor gaps at door frames | Frame shrinkage/movement |
| Hairline concrete surface cracking | Concrete shrinkage |
| Slight squeaking in timber floors | Framing drying out |
Monitor More Closely
| Observation | Significance |
|---|---|
| Cracks > 1 mm in plasterboard | Worth monitoring with tell-tales |
| Doors sticking in summer only | Seasonal moisture movement, normal, but track if progressive |
| Tile grout cracking in isolated area | Monitor, may indicate localised movement |
| Visible floor slope when checked with level | Quantify with measurements; acceptable if less than 4 mm/m |
Act Now, Contact Builder or Specialist
| Observation | Action Needed |
|---|---|
| Diagonal cracks > 3 mm at door/window corners | Report to builder as potential defect |
| Cracks with vertical displacement (stepping) | Report to builder; may need engineering assessment |
| Doors that no longer close (structural distortion) | Report to builder urgently |
| Cracking in external brickwork | Engineering assessment needed |
| Floor slope > 10 mm over 3 m | Quantify and report to builder |
Your Warranty Rights on New Homes
Under NSW Home Building Act, new homes come with:
- Statutory warranty for 2 years against non-structural defects
- Statutory warranty for 6 years against structural defects
Foundation movement that causes cracking beyond AS 2870 tolerances is a structural defect. You must formally notify the builder in writing of any defect. Keep records: photographs with dates, measurements, and any responses from the builder.
If the builder disputes the defect, you can apply to NSW Fair Trading for a building inspection. A structural engineer’s report supporting a defect claim significantly strengthens your case. See our guide on structural engineer reports for foundation work in NSW.
When First-Year Movement Becomes a Problem
The distinction between “normal first-year movement” and “a building defect” often comes down to:
- Magnitude: Was the design adequate for the actual soil class?
- Documentation: Was the soil tested, and was the design appropriate for the test result?
- Ongoing progression: Is movement slowing and stopping, or continuing to accumulate?
First-year movement that stabilises by month 18 and leaves cracks below 2 mm is generally within the performance expectation of AS 2870. Movement that continues at year 2 and 3, or produces cracking beyond the standard’s limits, suggests either a design shortcoming or an unexpected site condition.
In some cases, the initial soil classification was correct but a local condition, such as a leaking stormwater drain, a tree planted near the foundation, or a change in garden irrigation, has altered the moisture regime. In these cases, the defect is not in the original design but in a post-construction change.
Frequently Asked Questions
Q: My brand-new Wagga home has cracks after 3 months, is it a lemon? A: Not necessarily. Hairline plaster cracks in the first few months are expected. Photograph them, measure them, and monitor them. If they are still growing at 6 months and are wider than 2 mm, report them to your builder.
Q: Should I get an independent foundation inspection on a new home? A: For peace of mind, yes. A pre-handover inspection (before you accept the keys) is especially valuable. An independent building inspector at handover can identify early signs of foundation issues that may worsen over the first year.
Q: My builder says all new homes crack, is that true? A: Builders are right that some cracking is expected. They are not right if they use this to dismiss genuine structural movement. The AS 2870 standard specifies acceptable performance limits; cracking beyond those limits is a defect regardless of what the builder says.
Q: What if my soil was classified as M but the house is cracking like it’s on H2? A: This could indicate an error in the soil classification, the test may have been taken in a less reactive part of the site. Engage an independent geotechnical consultant to re-test and compare with the original report.
Q: The builder has gone out of business, am I covered? A: You may be covered by the Home Building Compensation Fund (HBCF), which provides insurance for residential building work in NSW. Contact NSW Fair Trading to determine your options.
Seeing movement in your new Wagga home and not sure if it’s normal? Request a free assessment, we can tell you where you stand and whether you have a warranty claim to pursue.