Window Replacement Cost Calculator

Understanding window replacement costs in Australia

What window replacement costs in Australia

Replacement windows in Australia typically cost $700 to $1,500 per window supplied and installed in 2026 for standard aluminium units in existing openings, with a whole-house replacement of eight to twelve windows commonly landing between $8,000 and $22,000. Individual pricing moves with size and style: a small awning or sashless unit sits at the lower end, a standard sliding or double hung window in the middle, a large picture or bay window at $1,800 to $3,500, and a sliding or stacker door unit anywhere from $2,500 to $6,000 depending on width and glazing. Those figures assume like-for-like replacement into the existing opening, which is the scenario that keeps costs predictable.

Frame materials and what they really cost

The frame is the largest single price variable. Standard aluminium is the Australian default: it is durable, cheap to fabricate, dimensionally stable and needs almost no maintenance, but it conducts heat readily so an unbroken aluminium frame undermines the performance of good glass. Thermally broken aluminium inserts a polyamide barrier between the inner and outer frame and typically costs 40 to 50 per cent more, which is money well spent in Melbourne, Canberra and Hobart where winter heat loss dominates. uPVC frames run roughly 25 to 35 per cent above standard aluminium, insulate very well and are increasingly common in southern states, though they need UV-stable formulations for harsh Australian exposure. Timber costs 50 to 60 per cent more, looks the part in period homes and is often the only option accepted in heritage areas, but it needs recoating every five to seven years. Composite timber and aluminium units, with a timber interior and an aluminium weather skin, are the premium option at roughly 80 to 90 per cent above standard aluminium.

Heritage overlays and planning approval

This is the trap that catches the most homeowners. If your property sits within a heritage overlay, a heritage conservation area or a character precinct, replacing windows is usually not a matter of choosing what you like. Councils commonly require planning approval for any change to the street-facing elevation and will frequently refuse aluminium replacements for original timber double hung sashes, requiring like-for-like timber joinery instead. That can double the material cost and add two to four months to the timeline while the application is assessed. Check the overlay on your property title or the council planning portal before you take a single quote, because ordering non-compliant windows in an overlay area is an expensive mistake to unwind.

Energy performance, ratings and the NCC

Windows are the weakest thermal element in most Australian homes, and the National Construction Code sets minimum performance for new work and significant alterations. Products are rated for U-value, which measures heat transfer, and Solar Heat Gain Coefficient, which measures how much solar radiation passes through. The right combination depends on your climate and orientation: southern states generally want a low U-value to retain heat, while northern climates prioritise a low SHGC to keep solar gain out. Low-E coatings, double glazing and thermally broken frames each move those numbers. Windows sold in Australia should carry an AFRC or equivalent rating and comply with AS 2047 for weatherproofing and structural performance, and in designated bushfire areas glazing must meet the relevant BAL rating, which adds materially to the cost.

Installation, flashing and the hidden costs

The install is where quality separates. A like-for-like replacement into an existing reveal is relatively quick, but the details determine whether the window leaks in three years. Proper practice includes a head flashing, a sill pan or tray, backing rod with an appropriate sealant rather than silicone alone, and correct packing so the frame is not distorted. Changing an opening size introduces structural work, a lintel and usually a building permit. Second storey work adds scaffolding at $1,500 to $2,500 for a typical house. Removal and disposal of old frames, particularly steel or heavily painted timber, is a separate line, and any home built before 1990 may have asbestos-containing sheeting or putty near the reveals, which requires a licensed removalist. Make-good of render, reveals and architraves after the swap is routinely underestimated.

Repair, reglaze or replace

Not every problem needs a new window. A failed double glazed unit showing fogging between the panes can often be reglazed with a new insulated glass unit into the existing frame for a fraction of full replacement. Sticking sashes, failed balance springs, worn rollers and perished seals are all repairable, and on a sound timber window a service and repaint extends life by decades. Replacement genuinely makes sense when the frames are rotten or corroded, when the glazing is single pane and the comfort or noise problem is significant, when the hardware is obsolete, or when you are already renovating the room and the access cost is being paid anyway. Use the estimate above as a planning bracket, then get two or three measure-and-quote visits with the flashing method and the make-good scope written into each.