Heritage Home Hurdles: Cracking in Old Melbourne Houses

Buying or renovating a heritage home in Melbourne? One of the most common issues you’ll come across is cracking. Understanding what causes these cracks (and how to fix them properly) is essential to protecting your home’s value and structural integrity.

In this series, I share insights from years of inspecting and restoring historic and heritage homes. I’ll talk what to look out for, what to avoid, and how to identify the hidden problems sellers sometimes try to conceal.

In this instalment, we’ll look at one of the most obvious and challenging hurdles: cracking.

Why Do Heritage Homes Crack?

Ground movement, also called subsidence, is the main cause. It occurs due to the swelling and shrinking of the soil beneath your house. When it rains, the soil absorbs water and expands. When the sun comes out, the moisture evaporates, and the soil contracts. In other words, our buildings are literally riding slow-moving waves. Surfs up!

Modern homes sit on engineered concrete slabs designed to withstand these forces. But, “it wasn’t like that in my day” - back then, this engineering know-how simply didn’t exist. Older homes were not built on solid, continuous bases, so as the ground moves, the building flexes (and not the selfie-in-the-mirror kind). As a result, cracking is inevitable.

Not All Cracks Are Equal

At an inspection, be wary of fresh paint. Ask yourself - what might it be hiding? Do the walls look lumpy or wavy underneath? If so, it’s most likely a cover-up! Literally. Be cautious and seek the advice of an architect or builder.

Cracks themselves are easy to spot:

• Hairline cracks are not a major concern. They can indicate minor movement, perhaps due to less reactive soil or a particularly stiff structure.

• Larger cracks, however, are a different story. These cause plaster to pop off, ceilings to crack, and floors to bow.

These are not things you can simply patch over. Sadly, I’ve seen many try! The cracks will reappear, as the ground will continue to expand and contract.

How to Fix Cracking in Old Homes

Addressing cracking is possible, but it’s labour-intensive and expensive. Still, it’s worth doing properly.

It starts with strengthening the footings, which is the structure your house sits on. This involves temporarily propping up sections of the house, digging underneath, and pouring new concrete or inserting piles to stiffen the base. This process is known as underpinning. Once that’s done, the cause of the cracking is corrected.

Then comes the cosmetic work: repairing cracks in the walls, ceilings, cornices, and roses. Older homes were built before plasterboard, and used traditional wet plaster, which must be repaired by specialist trades. Cornices and ceiling ornamentation often need careful restoration or replacement.

Wonky floors will be levelled as part of the underpinning process, as sunken sections are lifted to bring them back to level. Since floorboards are removed to access the subfloor, they’ll need to be relaid afterwards.

What to Budget For

This kind of work is complex, time-consuming, and can take a significant portion of your renovation budget. It’s not just about fixing the visible cracks, it’s about restoring the home from the ground up.

But once completed, your home will be structurally sound, comfortable, and ready to stand strong for generations to come.

Final Thoughts

Cracks are just the symptoms. The real work happens below, stabilising the foundations, then repairing the floors, walls, and ceilings above.

If you’re considering buying or renovating a heritage property, don’t overlook cracking. Have an architect experienced in heritage homes carry out a pre-purchase inspection to assess the extent of the issue and the likely repair costs.

If the work feels too much, it’s okay these projects aren't for everyone move on and find a home in better condition. But if you’re prepared to invest the time and money, the reward is immense. You’ll be living in a solid, beautiful piece of Melbourne’s history, restored to its full glory.

Lucky you.