Underpinning near you

The failure mode people rarely hear about is underpinning that works exactly as designed and still leaves the house cracked. If a footing is pinned down to firm material while the rest of the building continues to rise and fall with soil moisture, the pinned section becomes the one part that will not move, and the difference between it and everything else has to go somewhere. It goes into the brickwork at the junction.

That is why a responsible proposal starts with a period of observation rather than a quote. Crack widths and floor levels measured on at least two occasions separated by a change in weather will usually distinguish a building that has settled and stopped from one that is still going, and a building that is cycling from one that is sinking. It is slow, unsatisfying, and considerably cheaper than the wrong piles.

Correcting the cause also comes first. Where water is the driver — a downpipe discharging at the footing, a leaking drain, a change of ground level trapping moisture against one side — that has to be dealt with before support is added, because a structure is not stabilised while the thing moving it is still running. Any contractor willing to pin without asking where the water goes is not solving your problem.

Victoria puts underpinning squarely in the protection work regime. The City of Boroondara sets out the mechanism: Regulation 111 of the Building Regulations 2018 requires that neighbouring property is not affected or damaged by your work when you build or excavate near a boundary, and your building surveyor determines whether a protection works notice is required to be served on adjoining property owners. The notice is served under section 84 of the Building Act 1993, and section 246 of the same Act deals with false statements, which is a reminder that what you put on the form is a legal statement rather than a courtesy.

Practically, this changes the shape of the project. You need the adjoining owner's details, the surveyor's determination, and a documented description of what is proposed and how the neighbouring building will be protected, and that sequence has to complete before the work can proceed. It is the single most common reason an underpinning project starts later than the owner expected.

Other states and territories handle excavation near a boundary through their own building legislation, and the titles and forms do not match Victoria's. The obligation that is constant is the substantive one: if your work could undermine the building next door, you are responsible for it not doing so. Ask your building surveyor or certifier, in writing, which notice applies to your address.

Underpinning is approved as structural work rather than as maintenance. The City of Monash states that underpinning, re-stumping or otherwise altering the footing of a building is considered a structural alteration and requires a building permit, and that you will need a soil report to successfully apply for one.

The soil report is not a formality. It is the document that tells the designer what is under the footing, how deep competent material actually sits, and therefore which of the underpinning methods will work on your block. An underpinning design produced without one is a guess dressed as engineering, and the depth assumed in the quote is the number most likely to change once the first excavation is open.

Approvals, practitioner registration and licence classes are set by each state and territory, and this is work where the class matters rather than the general trade. Ask which registration covers underpinning where you live, and verify it on the regulator's own public register before signing anything.

Underpinning deliberately removes support from beneath a loaded footing and then puts better support back. Between those two moments the building is relying on the soil arching over a hole, which is why the sequence in the engineer's design is not a suggestion. Opening too many sections, or opening adjacent sections at once, is how underpinning causes the damage it was hired to prevent.

The excavations themselves are a work health and safety matter. They are deep, narrow, next to a structure and sometimes next to a boundary, and the people working in them need the trench support, the access and the exclusion zones that excavation work requires in your state. A homeowner's part in this is simple: stay out of the excavation, keep children and pets away from it entirely, and do not agree to a variation that speeds the job up by opening more of it at once.

Services are the other hazard. Sewer and stormwater drains, water services, gas and electrical mains all run at the depths underpinning works in, and older properties often have them where no plan shows. Locating them before excavation is part of the job, not an add-on.