Heritage commercial buildings carry a site’s character and still do a full day’s work. This one is a school building, and the client is the Victorian Department of Education. On a school campus in Berwick, in Melbourne’s south-east, stands a red-brick cottage about 95 years old — bay window, slate roof, chimneys and a cream timber verandah — converted into offices. This foundation repair in Berwick started with a website enquiry on 03/08/2022.

The school’s enquiry put it plainly: “It is a cottage that has been converted into offices and it has a lot of internal and external cracks and some movement of the structure… It is around 95 years old but has been renovated over the years.”

Old buildings on a school campus are part of its character, and they still get used every day. The repair had to stop the movement without changing what makes the building worth keeping.

Cracks ran through the brickwork, across the rendered verandah wall, up through a stone window head and over the internal doorways. The school had noticed movement in the structure too.

Patching those cracks would have looked fine for a season. With the ground still moving underneath, they’d have opened again.

And on a building this old, the wrong move is a big lift. Old masonry wants to be held still, not pushed around. Every repair also had to disappear into heritage red brick and coloured render.

A Buildfix structural engineer assessed the cottage and drew up two structural repair details: subsidence on 23/08/2022 and wall cracks on 27/10/2022. A floor-level survey across every room recorded readings down to −47mm against the datum, with the lowest along the front and side walls.

The cause was in the ground. The cottage sits on reactive clay with shallow footings — as the clay swelled and shrank through wet and dry seasons, the building moved with it. Trees and roots near the walls were drawing moisture out of the soil within the footings’ zone of influence, shrinking the ground and leaving voids beneath.

The repair was designed in 2 stages: GeoPoly™ to stabilise the foundation soils, then HelicalBar™ to structurally reinforce the walls. The school approved both in May 2023. Before any drilling, an independent plumbing inspector checked the site services by CCTV on 23/09/2023 — sewer, stormwater, mains water and gas located and marked in colour-coded paint, no repairs needed, site cleared to start.

From 25/09/2023 to 29/09/2023, Alberto Fernandez’s team worked through the cottage. Each day started with a review of the structural detail and the plumbing diagram. A Hilti PR30 laser and receivers were mounted on the external brickwork to track the building throughout.

Floorboards and carpet came up in the hallway, the rooms, the bay window and around the fireplace to reach injection points beneath the building. Holes were drilled to about 1,200mm and 2,400mm aluminium pipes inserted for DeepLift injections of GeoPoly™ GER60 — an expanding resin that fills the voids and compacts the soil under the footings.

210kg of GeoPoly™ went in. Every millimetre was deliberate. The lift was precision-controlled on the lasers and held to a 2–4mm range set for a 95-year-old masonry building — the job was to stabilise the foundations, not chase a big lift. Pipes out, holes patched.

On 06/10/2023, Todd Buzza’s team cut the existing mortar out 40mm deep along the cracks inside and outside the cottage and set 20–30m of 6mm HelicalBar™ in epoxy. The bars structurally reinforce the masonry, so the loads left after the injections are distributed evenly across the walls. Every area was re-pointed in a coloured mortar to match the original and cleaned up between 7:00am and 3:30pm.

On 01/10/2024, Brandon Piercy and Terry came back for the internal cracks. Walls were scanned for hidden cables with a Hilti scanner and drop sheets laid through the building. Loose and cracked render came off back to the brick, and a Hilti wall slitter with a vacuum cut slots 40mm deep, running at least 500mm past the worst of each crack.

The slots were cleaned and PVA-sealed, the HelicalBar™ pushed fully into the joints, and the walls rendered over with structural grout. The finish was colour-matched to the original with a custom mix of sand, cement, and red and sandstone dyes. More than 50m of HelicalBar™ went in on that visit.

Across 3 site visits: 210kg of GeoPoly™, more than 70m of HelicalBar™, a precision-controlled lift, and every crack repaired and the walls reinforced, with mortar and render matched to the original. No digging, nothing knocked down. The school paid in full.

Responsible for an older building on a school, council or commercial site that’s cracking or moving? A free site assessment measures the floor levels and explains what non-invasive underpinning and wall crack repair can do — before anyone reaches for a patch.