Rewiring and re-plumbing a 1920s Adelaide home

Original wiring in 1920s Adelaide homes is typically one of three types: knob-and-tube (individual copper wires supported by porcelain insulators), cloth-covered TPS (twin and earth with fabric insulation), or early plastic-insulated wiring from post-war reworks.

All three are at or past safe end of life. Knob-and-tube is a fire risk. Cloth-covered TPS insulation embrittles and cracks over decades, exposing live conductors. Even early plastic wiring often lacks earth conductors and modern protective devices.

A full rewire is the correct response. Do not attempt partial rewires that mix new and old wiring; the interface points become unreliable and the fault-finding on the mixed system becomes impossible.

A full rewire during a renovation adds a modest cost premium over a partial rewire, and delivers a home that is safe for another century. This is not the place to compromise.

Original plumbing in Adelaide character homes was typically galvanised iron pipe. Over decades, galvanised pipe corrodes internally, building up mineral deposits that reduce internal diameter and restrict water flow.

By ninety years of age, a galvanised pipe original to a 1920s home may have half of its original bore, if it has not developed pinhole leaks. Water pressure at the fixtures is a fraction of the pressure at the meter.

The correct response is full replacement with modern copper or PEX (crosslinked polyethylene) plumbing. Copper is the traditional choice and works well for hot and cold water. PEX is more flexible, less prone to freezing damage, and generally faster to install.

Plan the plumbing renewal at the same time as electrical rewiring. Both involve accessing behind walls and above ceilings; doing them together halves the total access disruption.

Original gas services in 1920s Adelaide homes typically comprised a gas meter, gas cookers and often a gas water heater or gas heater. Many homes still have residual gas piping even after some appliances have been converted to electric.

A renovation is an excellent opportunity to remove gas entirely. The reasons are: safety (old gas piping is less reliable than modern; smell tests do not catch small leaks), simplicity (removing gas eliminates the meter, the appliance connections and the maintenance regime), and cost (avoiding ongoing gas supply charges that apply even to low-usage households).

Removing gas requires disconnection by SA Power Networks (for the meter and supply) and removal or capping of internal piping. Coordinate with a licensed plumber and confirm the disconnection is registered on the SA Power Networks database, so any future owner sees the correct utility status.

The one caveat is if the household strongly prefers gas cooking. Some cooks resist induction. If so, keep gas to the kitchen only and remove elsewhere. Most cooks who make the transition find induction meets their needs after a short adjustment period.

A services renewal is the ideal moment to install modern data cabling, smart-home wiring, and future-proofing that would be difficult to retrofit later.

The mainstream recommendation for a family home in 2026 is: category 6A ethernet cabling from a central patch panel to at least one point in every room; a central patch panel with rack space for a router, switch and NBN termination; RG-6 coaxial cabling for TV backup if free-to-air TV reception is expected.

For smart-home infrastructure, run a low-voltage bus (typically KNX, CBUS, or similar) if you plan integrated lighting and blind control. This is not essential; wireless systems (Zigbee, Z-Wave, WiFi-based) can achieve similar outcomes with much lower installation cost. Discuss with a smart-home integrator before choosing.

For solar and battery, provide capacity in the switchboard for solar and battery isolators, and provide a wall pass-through where the future battery would live. Even if solar and battery are not part of the initial scope, this pre-work saves significant retrofit disruption later.

Services renewal sits inside a broader renovation program and must be coordinated with the rest of the work.

The typical sequence: demolition and strip-out first, then structural work and any damp remediation; services first-fix (rough-in) before internal linings; internal linings, plaster and floor levelling; services second-fix (fixtures, switches, outlets); final decoration.

The most common sequencing error is closing walls before services first-fix is complete. This forces expensive rework. A weekly site meeting with the electrician, plumber, and builder present catches most sequencing issues before they become expensive.

On a full services renewal, book each trade to be on site for extended blocks rather than as one-day visits. A rewire of a full four-bedroom home is typically two to three weeks continuous work; a plumbing renewal similar. Fragmented scheduling adds cost and creates coordination problems.