Sand near the water, clay further in. From Nelson Bay to Raymond Terrace either can let a footing down, and the house shows it in a door that catches, brickwork stepping open or a floor sunk on one side. Underpinning is the answer: new support under that footing, below the ground that failed. That is our work across Port Stephens. Let us know the suburb and what you've noticed.
Get a Quote →Dig beside a brick house at Nelson Bay, Shoal Bay or Soldiers Point: a concrete footing, on sand, and the sand holding the house up. When the sand lets go under one corner, that corner drops and the others don't. The wall above is pulled two ways and its mortar joints open in a stair-step. Underpinning takes the weight off the sand that let go and carries it down to ground that holds.
Around Port Stephens two kinds of ground do most of the damage: deep sand on the coast, and clay further in at Raymond Terrace and Medowie. Sand moves with water: it gets carried out from under a footing, or packs harder under one corner than another. Clay swells with water and shrinks without it, so the footing rides up and down until a corner stays down. A big tree dries the clay on its side, so that side shrinks first.
Two ways to put support back. A pier is a new leg under the footing: concrete poured into a pit under it, or a steel pile wound down into firm ground. Resin skips the digging. Injected at the footing as a liquid, it swells as it cures, tightens loose ground and can lift a dropped slab. On sand this deep the footing usually has to bear lower, which is pier work.
Sand doesn't warn you. We have seen it go a little every wet season with only a sticking door to show. So we look at what the footing sits on before the cracks. On the day that means a paint mark for every pier, paving lifted, and a pit beside the footing down to its underside. The pier goes up in that pit, wedged hard against the footing so the load is on it before we backfill and move to the next mark. What's left is turned soil along the wall and paving to put back.
Traditional mass concrete underpinning — excavating beneath existing footings in sections and pouring new concrete to a stable bearing depth. The proven method for most residential jobs.
Steel screw piles wound into stable ground beneath the foundation. Faster than concrete, less excavation, minimal vibration — ideal for sandy Port Stephens soils and tight-access sites.
Replacing deteriorated timber or concrete stumps under raised-floor homes. Includes relevelling the floor to remove bounce, slope and unevenness.
Epoxy injection, stitching and reinforcement of cracked masonry walls and slabs — often done alongside underpinning to address both cause and symptom.
Sand. Hunter Water describes the Tomago Sandbeds as an aquifer running 25 km north-east from Tomago towards Lemon Tree Passage, in sand that averages 20 m deep and reaches 50 m in places. Over sand that deep, a footing repair will usually get its support from the sand itself. The separate Tomaree Sandbeds, at the end of the Tomaree Peninsula, are the peninsula's primary water source, and Anna Bay, Nelson Bay, Fingal Bay and Shoal Bay sit on their outskirts.
Water. Port Stephens Council's profile on the NSW Flood Data Portal says flooding here comes from major rivers in the west and from low-lying ground meeting the coast and estuaries in the east. Council's 2017 Anna Bay and Tilligerry Creek Flood Study calls flooding in its study area complex, because in a major flood, floodwaters can interact with the Hunter River, Fullerton Cove and Tilligerry Creek, all tidally influenced. Along the shore, Council's Coastal Management Program, certified by the NSW Government, deals with issues like coastal erosion. The Bureau of Meteorology's Williamtown RAAF station averages 1,134 mm of rain a year, with February to June the wettest stretch.
Rules. Under clause 7.1 of the Port Stephens Local Environmental Plan 2013, digging on land shown on the Acid Sulfate Soils Map can need development consent, depending on the land's class, how deep the work goes, how much soil it disturbs and whether it's likely to lower the watertable. Ask the engineer to check that map and the flood studies before the job is scoped.
Covering Port Stephens, including Nelson Bay, Shoal Bay, Fingal Bay, Corlette, Salamander Bay, Soldiers Point, Boat Harbour, Anna Bay, Williamtown, Salt Ash, Medowie, Raymond Terrace, Heatherbrae, Tanilba Bay, Lemon Tree Passage and Karuah. Port Stephens Council's profile notes that the harbour's northern shoreline is the boundary with the MidCoast council area, so homes on that side of the water deal with MidCoast Council, not Port Stephens Council, for any council approval.
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