Get a Quote
πŸ—οΈ

Underpinning & Foundation Repair Across the Central Coast

Cracked walls, doors that bind, a floor that runs downhill: on the Coast that usually means a footing has moved, and underpinning puts firm support back under it. We do that work from Patonga to Lake Munmorah. Tell us what the house is doing, which suburb it is in, and roughly how long it has been going on.

Get a Quote →
✓ Covers the Central Coast ✓ Concrete Pier Underpinning ✓ Structural Crack Assessment

What Underpinning Actually Involves

Every wall in a house stands on a footing, a strip of concrete just below the ground, and the footing only works while the ground under it stays put. On the Central Coast that ground changes over short distances. Kariong and Somersby sit on Hawkesbury sandstone and shale, generally stable, with pockets of clay-rich soil between the rock layers. Parts of Gosford, Wyong and the low ground near the lakes and the coast sit on reactive clay or fill. Clay shrinks as it dries and swells as it wets, fill settles for years after it was placed, and a tree or a leaking pipe can do either to one corner and not the rest. When one footing drops and its neighbours do not, the brickwork between them cracks in a stair-step, a door goes out of square and the floor leans.

Underpinning is how we give that footing something solid to sit on again, and there are two ways to do it. Where the movement is moderate, we inject an expanding resin under the footing: it fills the voids the dry clay left, firms the ground and can lift the footing back toward level. Where a footing has dropped further, we dig a pit beside it and under it, and pour a concrete pier that carries the load down past the soft ground to something that holds. On the Coast a pier can also be what Council asks for: near a drainage easement or a Council stormwater pipe in the former Gosford area, DCP 2022 requires piers taken at least as deep as the pipe, with a structural engineer's details before approval.

It starts with an engineer's level survey, so we know which footings have moved and by how much, and a look at the cause, usually drainage or a tree, because a pier under a footing that keeps getting wet only moves the problem along. On the day, resin means drill holes along the outside of the wall and a lift you watch on the level. Piers mean the ground along the dropped wall opened one short section at a time, each pier set hard against the footing before the next pit is dug, so the wall is never left unsupported. You stay in the house, the garden goes back, and the cracks are patched last, once the movement has stopped.

What to keep an eye on, and what underpinning does about it The four signs a footing has moved 1 2 3 4 1 A stepped crack running from a window or door corner 2 A door or window out of square: sticking, or not latching 3 A gap opening at the base of a wall, or along the path 4 One corner of the house sitting lower than the rest What underpinning does Before After soil that has shrunk, swelled or washed firm ground The footing has gone down with the soil. The wall above it cracks. A pier carries the footing down to firm ground, or resin is injected under it to lift and fill.

Underpinning Services We Cover

πŸ’‰

Resin Injection Underpinning

Fast, low-disruption footing lift and stabilisation using expanding polyurethane resin, suited to moderate movement across most Central Coast suburbs.

πŸ—οΈ

Concrete Pier Underpinning

Traditional excavated concrete piers for more severe or long-standing movement, taking footings down to more stable ground beneath.

πŸ”

Structural Crack Assessment

Level surveys and crack monitoring to work out whether movement is active, historic or seasonal before recommending any fix.

🌱

Drainage & Tree Root Investigation

Checking for the drainage, tree-root or plumbing leak causes behind footing movement so the underpinning has a better chance of holding long-term.

Signs You May Need Underpinning

Diagonal cracks running from the corners of doors and windows
Doors or windows that have started sticking or won't latch properly
Gaps opening up between skirting boards and the floor
One corner or side of the house visibly lower than the rest
Cracks in brickwork wider than a few millimetres, or growing
Cracks that reappear in the same spot after being patched
Not Sure If It's Serious? Send us a photo of the crack with a ruler for scale and roughly where it is on the house. Whether a crack is structural or cosmetic is a call for a qualified engineer.

Why a Central Coast underpinning job starts with the address

Central Coast Council does not treat the region as one kind of ground. Chapter 3.7 of its Development Control Plan 2022 (the DCP) rates landslip potential with matrices keyed to the local geology, from Hawkesbury Sandstone, Patonga Claystone and the Terrigal Formation to aeolian, dune and barrier sands and alluvium, swamp and estuarine deposits. A lot rated Hazard Category 2 or above needs a geotechnical report with a development application, and a Category 4 lot needs a comprehensive report covering adjoining lots too.

The address adds its own rules. In the former Gosford area, DCP Chapter 3.1 requires piers along a drainage easement boundary to go at least as deep as the invert of the pipe or culvert, and no digging within 2 m of the easement without Council approval. On the open coast from Wamberal Beach to Patonga Beach, the coastal hazard chapter in force in 2026 required footings to bear safely below or beyond the zone of reduced foundation capacity. Subsidence Advisory NSW's Mine Subsidence District maps take in parts of the Council area and are labelled with localities such as Budgewoi and Lake Haven. Check a given address on the NSW Planning Portal Spatial Viewer.

Water matters too. The Bureau of Meteorology's Gosford record (Narara Research Station, 1916 to 2013) averages 1,328 mm of rain a year. On the Peninsula, the DCP names drainage black spots in Woy Woy and Umina where Council says the problems cannot be readily overcome. Any diagnosis of footing movement here should include the water.

Suburbs across the Central Coast Council area

This site takes underpinning and footing repair enquiries from across the Central Coast Council area, including Patonga, Woy Woy, Umina, Kariong, Somersby, Gosford, Erina, Terrigal, Wamberal, The Entrance, Wyong, Blue Haven, Lake Haven, Gorokan, Budgewoi and Lake Munmorah. If your suburb isn't listed, you can still send an enquiry.

Get a Underpinning Quote

Tell us what you need and where the property is.

Your details come to us. Privacy.

Get a Quote →