What a Structural Engineer Checks in an Old House

When a structural engineer walks through an older Melbourne home, the goal is simple. Work out whether the structure is safe, whether it is still moving, and what it will take to keep it standing well into the future. That means looking past cosmetic finishes and reading the building as a system, from the soil under the footings all the way up to the ridge of the roof. This guide sets out exactly what a structural engineer looks for in an old house, why each item matters, and the warning signs that are specific to Melbourne period homes.

Foundations and footings: stumps, reactive clay and settlement

The foundation is the first thing assessed because almost every other defect in an old house traces back to it. Melbourne sits on large areas of reactive clay, which swells when wet and shrinks when dry. That seasonal movement lifts and drops footings, and older homes were rarely built to tolerate it.

Many Victorian and Edwardian homes across the inner and middle suburbs sit on timber stumps rather than a concrete slab. A structural engineer checks the stumps for rot, splitting, ant capping, and whether they have sunk, leaned or lifted. Stumps that were sound eighty years ago are often near the end of their life. Brick and bluestone footings from that era are also inspected for stepped cracking and lateral movement.

On slab-on-ground homes and later brick veneer builds, the engineer looks for differential settlement, meaning one part of the slab has dropped relative to another. The tell tale signs are cracks that widen toward the top, floors that fall away toward an external wall, and gaps opening between the skirting and the floor.

Wall cracking and movement: reading what the cracks mean

Not every crack is a structural problem. A large part of the inspection is separating harmless shrinkage cracks from cracks that signal ongoing movement. The engineer measures crack width, checks whether cracks step through brickwork or run diagonally from window and door corners, and looks for signs the crack is still opening.

Diagonal cracks running from the corners of openings, cracks that pass through bricks rather than following the mortar, and cracks wider than about 5mm all raise the level of concern. The Australian reference point is the CSIRO damage classification, which grades cracking from negligible up to severe.

In older double brick and solid masonry homes, the engineer also checks for bowing walls, separation between the two brick skins, and rusting wall ties that push courses apart over time. A detailed structural engineer report Melbourne homeowners can rely on will grade the cracking against this framework and set out whether movement is finished or ongoing.

Subfloor, timber decay and termite damage

Under a period home with a suspended timber floor sits a subfloor space that tells much of the story. The engineer inspects bearers, joists, stumps and the underside of the floorboards for rot, splitting, sagging and insect attack.

Poor subfloor ventilation is one of the most common issues in Melbourne period homes, particularly where later landscaping, paths or decks have buried the original air vents. Trapped moisture then feeds both timber decay and clay movement, so the engineer treats ventilation as a structural matter, not just a comfort one.

Roof structure and sagging

The roof of an old house carries significant load and is often where original timber sizing no longer meets the demand placed on it. The engineer checks the ridge line for sag, the rafters and ceiling joists for spread, and the condition of any strutting and underpurlins in the roof space.

A dipping or wavy ridge line seen from the street is an early sign the roof framing is spreading or that a supporting wall below has moved. Inside the roof space, the engineer looks for cut or removed structural timbers, water staining from past leaks, and rafters that have twisted or split. Old terracotta tile roofs are heavy, and where framing was never designed for the load, or was later weakened, the sag becomes visible over decades.

Load-bearing modifications by previous owners

Older homes are rarely in original condition. Decades of renovations mean walls have been removed, openings widened and rooms opened up, often without engineering input or a permit. This is one of the highest priority items in any old-house inspection.

The engineer works out which walls are load-bearing and checks whether any have been removed or altered. Where a wall has been taken out, the questions are whether a beam was installed, whether it is the right size, and whether it bears onto something solid at each end. Undersized beams, beams with no proper support at the ends, and walls simply removed with nothing put back are all found regularly in older Melbourne homes.

Signs that a past modification is failing include sagging ceilings along the line of a removed wall, doors that have started jamming near a renovated area, and fresh cracking above a wide opening. Anyone planning further changes should get a proper load bearing wall assessment before work starts, so a new beam is sized correctly and the existing structure is checked first.

Moisture and drainage

Water is the quiet driver behind a large share of structural defects in old houses. The engineer assesses how water moves around and under the building, because uncontrolled moisture attacks both timber and the reactive soil beneath the footings.

• Site fall and whether the ground slopes toward or away from the house
• Downpipes discharging next to footings rather than into a stormwater system
• Rising damp in solid masonry walls and failed or absent damp courses
• Leaking gutters and valleys staining walls and roof timbers
• Garden beds, paths and paving trapping water against the base of walls

In reactive clay areas, keeping soil moisture stable is one of the most effective ways to slow footing movement. Broken drains, leaking taps and poor site drainage create wet and dry patches that make the clay heave unevenly, which is why drainage findings often sit alongside the footing recommendations in the report.

Signs specific to Melbourne period homes

Certain patterns show up again and again in the local housing stock. A structural engineer familiar with Melbourne homes reads these quickly.

Weatherboard homes on timber stumps often show sloping floors and racked door frames where stumps have sunk. Solid double brick Victorian terraces show stepped cracking at party walls and window heads. Interwar homes with tuckpointed brickwork develop cracking where original footings were shallow. Early brick veneer homes from the postwar decades are prone to articulation cracks where the brick skin moves against the timber frame. Ageing timber stumps, shallow footings and reactive soil are the three threads that connect nearly all of it.

The inspection and the report

A structural engineer inspection of an old house is a visual assessment of every accessible element, backed by measurements, level readings and photographs. The engineer reads the building as a whole, then explains in a written report what was found, how serious each item is, what is causing it, and what should be done. Recommendations are usually staged by urgency, from immediate safety items through to longer term maintenance. Booking structural engineer inspections early, before a purchase or a renovation, means decisions are made on evidence rather than guesswork.

Frequently asked questions

What will a structural engineer look for in an old house?

A structural engineer looks at the load-bearing parts of the house: foundations and stumps, wall cracking and movement, subfloor timbers and any decay or termite damage, roof framing and sag, and any load-bearing walls previous owners have altered. Moisture and drainage are assessed too, because water drives much of the movement in older Melbourne homes.

Are cracks in an old house a serious problem?

Not always. Hairline shrinkage cracks are cosmetic. Cracks become a concern when they run diagonally from window and door corners, step through brickwork, exceed about 5mm, or keep widening over time. The engineer grades cracking against the CSIRO classification to separate harmless cracks from active structural movement.

How much does a structural inspection of an old house cost?

In Melbourne, a structural inspection of a house typically ranges from a few hundred dollars up to around $1,000 or more in AUD, depending on the size of the home, access to the subfloor and roof space, and whether a full written report is required. A fixed fee is usually quoted once the scope is clear.

Should I get a structural inspection before renovating an old house?

Yes. A structural inspection before renovating confirms which walls are load-bearing, whether past changes were done correctly, and whether the footings and stumps can support the planned work. It is far cheaper to design around the existing structure than to discover a problem mid-build.

What is the difference between a building inspection and a structural inspection?

A building inspection is a broad check of the whole property, covering many systems at a general level. A structural inspection is carried out by a qualified structural engineer and focuses in depth on the load-bearing structure, with an engineer-stamped report that grades defects and recommends engineered repairs. The two are complementary, not the same.

Talk to a structural engineer about your old home

If an older Melbourne home is showing cracks, sloping floors, sticking doors or signs of past alterations, a structural assessment turns uncertainty into a clear plan. Principal Built Engineering carries out structural inspections and reports on Victorian, Edwardian, weatherboard and brick veneer homes across Melbourne. To arrange an inspection, get in touch and describe what you are seeing.