Renovating an older home can be incredibly rewarding. Character features, solid construction and established neighbourhoods are some of the reasons many people choose older properties over new builds.
But older homes also come with surprises.
From moisture problems under floors to outdated electrical systems hidden behind walls, there are a number of issues that homeowners often don't discover until renovation work begins. Understanding these risks early can help you plan more realistically - both financially and structurally.
To help explain some of the most common challenges, we spoke with Steve Tonkin, Director of Tommico Renovations, who specialises in renovating older homes across Sydney's Inner West, particularly early-1900s terrace houses.
Steve says many of these homes have stood the test of time for good reason:
"Most terrace houses are built surprisingly well for their age, they used lime mortar render with double brick construction and hardwood joists, which has attributed to their longevity. The soft lime render and mortar allowed the houses to have built in movement and the hardwood joist and flooring (kauri pine, baltic pine) were chosen due to their resistance to termites.
Terrace homes offer huge potential to create a modern-standards home in the heart of the city, it's something you just can't recreate anywhere else."
1. Moisture and Damp in Subfloors
One of the most common issues in older homes is moisture beneath the floor.
Many early 20th-century homes were built with minimal subfloor ventilation by modern standards. Over time, poor airflow combined with rising damp or drainage issues can create persistently damp conditions beneath the house.
This can lead to problems such as:
- Rotting floor joists
- Mould growth
- Termite attraction
- Sagging or uneven floors
Addressing the issue may involve improving drainage, installing additional ventilation, repairing damaged timber, or rebuilding sections of the subfloor.
Steve says conditions can vary dramatically from one property to the next:
"Some terrace houses have surprisingly good ground clearance and airflow under the subfloor, but we have seen some really bad ones where the floor joists are almost sitting on the dirt, this needs to be rectified. Another issue we come across is new outdoor pavers set higher than the air vents. I have seen two properties where the pavers direct flowing water into the air vent under bedrooms.
While adding mechanical ventilation under the sub floor helps, the best remedy is proper ground clearance by excavating the dirt build up and allowing the air vents to cross ventilate from either side of the house. Removing outdoor ground works that are directing water towards the house. Then mechanical ventilation and chemical injection to create a damp proof course is an added benefit."
Because the subfloor is rarely inspected closely during a property purchase, these problems often only become apparent once renovation work begins.
2. Structural challenges when opening up layouts
Many older homes - particularly terraces - were built with a series of smaller rooms separated by structural walls.
Modern renovations often aim to create open-plan kitchens and living spaces, which means removing or modifying those walls. But doing so requires careful structural design.
Once walls are opened, builders may discover:
- Load-bearing walls that require steel beams
- Irregular or undersized framing
- Movement in old masonry walls
- Structural work from previous renovations
Engineering solutions are often needed to safely redistribute loads while maintaining the integrity of the building.
Steve says that while these challenges are common, they're usually manageable with the right planning.
"The beauty of terrace homes is they are fairly similar in their construction and floor plan. The most common structural beams we put in are called 'portal frames', which open up the space but also provide lateral stability that was lost by removing the perpendicular walls.
It's entirely possible to open a terrace house from the front door right through to the backyard while preserving the integrity of the original structure."
3. Electrical Switchboard and Wiring Upgrades
Electrical systems in older homes frequently need upgrading during renovations.
Many houses have had multiple electrical additions over the decades, leaving a mixture of old and new wiring systems. Switchboards may also lack the capacity or safety protections required for modern households.
Common issues include:
- Outdated switchboards
- Insufficient circuits for modern appliances
- Lack of safety switches
- Ageing wiring that no longer meets current standards
Renovations are often the ideal time to upgrade the system, particularly when new kitchens, air conditioning, EV chargers, or electric appliances are being installed.
Steve says this is one of the most predictable issues they encounter:
"With most terrace houses we renovate, around 90% will need a switchboard upgrade, and sometimes a new power connection from the street. This is something we are aware of and factor into the budget from the start.
The new switchboard allows more 'feeds or circuits' into your home. Whereas previously one feed would power all of downstairs, we now have many feeds to make your home safe. For example individual oven circuits, zip taps, dedicated feeds for the bathroom and kitchen. This brings the terrace home up to modern standards and provides a safer home"
4. Traditional Wall Construction
Walls in older homes are very different from modern plasterboard construction.
Many early houses use lath and plaster, brick with render, or other traditional materials that behave differently over time. Movement in the building, moisture, or previous repairs can leave walls cracked, uneven, or fragile.
When renovating, builders often need to repair, stabilise or re-line sections of wall before new finishes can be installed.
Steve says moisture management is often the key consideration.
"For new extensions, ventilated cavity cladding with a proclima system makes the building envelope weathertight and has the potential to then become a passive home. Brick veneer is another great wall system for extensions, particularly on the ground floor as it ties in the old brick building to the new extension in a cohesive manner. Then modern cladding is great for the upper floors.
For the existing terrace house walls, the best system is preventing moisture getting to the bricks. We like to implement:
- Proper ground clearance under the joists to allow airflow
- Proper cross ventilation by making sure there are enough vents in the outside walls and they are large enough
- Directing water away from the building, providing new stormwater drainage and sometimes an ag line around the perimeter of the building under the soil
- Repair all mortar joist, roof leaks and reseal the chimneys
Once the above is implemented, the preferred wall system below provides a moisture barrier from the outside, allows the inside to breathe, and provides thermal block from the outside brickwork.
- Emerclad exterior paint
- 20mm batten system
- 13mm plasterboard
If we are patch repairing we will use lime render to match the existing render and allow the original bricks to breathe."
Planning Ahead for Renovating Older Homes
None of these challenges mean older homes are a bad investment. In fact, many homeowners feel the character and location of these properties make the extra effort worthwhile.
However, it's important to approach renovations with realistic expectations.
Working with builders who regularly renovate older homes can make a significant difference. Experience helps identify potential risks early and allows them to be factored into the planning and budget.
Steve believes early builder involvement is one of the best ways to avoid costly surprises:
"The best way to plan your new renovation for an inner west terrace is to involve a builder early in the process. We provide pre construction service that will provide guidance and provide a detailed estimate for the concept design, updated price after engineering, then a final price after pc item selection.
Throughout the process we will also build a 3D model of the structural elements of the project. This helps us better understand the build and accurately quote the project, and with this we can look to ways to value engineer."
Final thoughts
Older homes often hide complexities that aren't visible until renovation work begins. Moisture issues, structural changes, ageing electrical systems and traditional building materials can all add unexpected work to a project.
Understanding these possibilities early - and working with a builder experienced in older homes - can help homeowners plan more confidently and avoid costly surprises along the way.