A crack that opens every dry summer and closes after rain, a door that jams, a floor sloping toward one wall: Tamworth's black clay moves houses, and underpinning stops the footing moving with it. Tell us which walls are cracking, when it started and what the ground around the house is doing.
Get a Quote →Start with what the house sits on. The black and grey basaltic clays through East Tamworth, Calala and out toward Moore Creek are highly reactive ground: they swell hard when wet and shrink hard when dry, and the New England swing from drought to heavy rain works that cycle harder than most of the state ever sees. A footing is the concrete strip a wall stands on. When the clay under one part of it shrinks in a long dry spell, that part drops; when the rain comes the clay swells and it lifts again. A house built decades ago on shallow footings, or a newer one on fill that was never compacted properly, moves the most, and every cycle opens the cracks a little wider.
Underpinning takes the footing off the ground that keeps moving and rests it on ground that does not. For moderate movement we inject an expanding resin under the footing: it packs the voids the shrinking clay left, firms the ground and lifts the footing back toward level. For a footing that has dropped further, we dig under it and pour a concrete pier that reaches past the reactive layer, so the wall above rides on the pier instead of the clay.
Before any of that, an engineer surveys the floor levels so we know exactly which footings have dropped or lifted and by how much, and we look for the trigger, usually drainage or a tree drawing the water out of the clay on one side of the house. Fix the water and the pier holds; leave it and the ground keeps working on whatever is under the footing. On the day, resin is drill holes along the outside of the wall and a slow lift you watch on the level. Piers are pits dug one at a time along the dropped wall, each one poured and set against the footing before the next is opened, and you stay in the house while it happens. The cracks get patched last, once the movement has stopped, because patching them first only hides the next season's movement.
Fast, low-disruption footing lift and stabilisation using expanding polyurethane resin, suited to moderate reactive-clay movement.
Traditional excavated concrete piers taken past the reactive clay layer for severe or long-standing movement across Tamworth's black soil suburbs.
Level surveys and crack monitoring through a full wet-dry cycle to confirm whether movement is seasonal, active or historic before recommending a fix.
Checking irrigation, drainage and nearby trees, three common triggers of reactive clay movement, which gives the underpinning a better chance of holding.
Soil. Tamworth Regional Council's Development Control Plan 2010 (Amendment No. 20) has a Geology control for general housing, dual occupancy and multi-dwelling development. The design must consider highly reactive soils, saline soils, erosive soils, soils of low wet strength and steep slopes, and document how each one is dealt with. Hold an underpinning design to the same standard and ask the engineer what soil information it rests on.
Weather. Bureau of Meteorology averages for Tamworth Airport, from records since 1993, show 660 mm of rain a year on about 61 rain days. November is the wettest month at 83 mm and April the driest at 30 mm. The January mean maximum is 33.1°C, and mean 3 pm humidity through summer is about 35 to 40 per cent. Reactive clay shrinks as it dries and swells as it wets up, so a crack measured on one day tells you little. Track it through a dry spell and a wet one before anyone sizes a fix.
Flood. HydroSpatial's March 2023 report for Council's Tamworth City Wide Floodplain Risk Management Study and Plan covered the Peel and Cockburn rivers, the Goonoo Goonoo, Wangaratta, Timbumburi, Boltons and Murroon creeks, Oxley Vale, and East and North Tamworth. In December 2025 the Inverell Times reported a Council manager saying the 2023 modelling had a glitch. The revised modelling showed lower projected flood levels, including 500 mm lower on Goonoo Goonoo Creek. Flood levels feed into floor heights and footing design, so get the figure for your address from Council first.
Enquiries are welcome from East, West and North Tamworth, Hillvue, Calala, Kingswood, Oxley Vale, Moore Creek and Nemingha, and from anywhere else in the Tamworth Regional Council area. If Council has given you a flood level for the property, mention it in your enquiry.
Tell us what you need and where the property is.