uPVC Windows Installation Guide for Australian Conditions

What to check, how to seal, and where most mistakes happen when fitting uPVC windows

If your window is not level or sealed properly, you’ll get draughts, condensation, and stuck sashes. This guide shows how to carry out uPVC windows installation correctly, following Australian standards.

What You’ll Need

Basic Tools

• Drill and screwdriver
• Spirit levels (more than one size)
• Pry bar
• Safety gloves and goggles

Recommended Extras

• Glass suction lifters
• Packing shims
• Lifting straps for heavy units
• Expanding foam or silicone
• Sealing tape or membrane

For a 1.5×2m double-glazed unit, use suction lifters and at least two people. It’s too heavy to handle alone.

Preparation

1. Measure the new window and the opening. Leave enough clearance for squaring and sealing.
2. The opening must be plumb and level. Use a laser or long level.
3. If replacing, remove trims and break the seal with a utility knife. Remove glass before taking out the frame.
4. Clear old foam, dust and render. Keep the sill base if it’s stable.

If the frame won’t budge, cut the mullion first — it will come out in parts easily.

Sealing Options

Silicone alone doesn’t hold up well over time. Use one of these:

Option 1 – Expanding Foam Tape

• Applies around jambs and head
• Expands after installation to fill the gap

Illbruck 600 tape suits 4–8mm gaps and doesn’t need external caulking.

Option 2 – Flexible Membrane + Foam

• Stick membrane around the window with 50mm overlap
• Fill the perimeter gap with foam
• Seal membrane edge with adhesive

Both methods improve airtightness and meet WERS energy efficiency standards.

Frame Installation

1. Leave sashes closed. Insert the frame carefully and check alignment.
2. Use packers at fixing points. No more than 2mm deviation allowed.
3. Fix with coated screws: 300mm spacing on hinge side, 450mm elsewhere.
4. Seal any bottom holes with silicone to avoid water entry.

Never fix through the bottom profile in brick walls. Moisture will find its way in.

Glazing – Use Toe and Heeling

1. Insert bridging packers at top (handle side) and bottom (hinge side)
2. Fit glass, leaving a gap for extra shims
3. Add glazing packers until the sash swings freely
4. Secure with silicone and install glazing beads

If the sash is sagging, wedge the top corner to lift it back in line.

Internal Finishing

1. Fill all gaps with foam
2. Install trims and screw timber reveals at 450mm centres
3. Tape around the frame and apply acrylic sealant
4. Remove tape before the sealant skins over

If there’s a visible gap near plaster, use a uPVC corner trim and seal it with silicone.

External Finishing

1. Clean surfaces first
2. Install sill end caps and exterior trim
3. Seal gaps with foam or tape
4. Use masking tape when applying silicone for a clean finish

If the sill doesn’t sit flush, shave back insulation under it and fix with adhesive.

Maintenance Tips

• Wipe frames with mild soapy water
• Check gaskets and handles yearly
• Lubricate hinges if stiff

Regulatory Standards

Ensure compliance with:

• National Construction Code (NCC) — for structural and fire safety
• WERS (Window Energy Rating Scheme) — for thermal ratings and rebate eligibility

Installation Checklist

Step	Done
Checked frame and opening dimensions	✓
Old unit removed and site cleaned	✓
Sealing system applied	✓
Frame levelled and fixed	✓
Glass installed correctly	✓
Internal and external finishing done	✓
Sash opens smoothly	✓

Professional uPVC window installation in Sydney ensures reliable thermal and acoustic insulation. WindowsFactory provides installation services tailored to Australian conditions. Learn more on the uPVC windows installation page.