How to Measure Window Openings for Custom Aluminium Windows in Australia

Quick Answer

Accurate window measurements are essential when ordering custom aluminium windows. Builders and installers should measure the opening width, height, diagonals, wall construction and installation conditions before manufacturing begins. Correct measurements help ensure proper fitting, waterproofing, performance and efficient installation.

Introduction

Custom aluminium windows are manufactured according to project-specific dimensions.

Unlike standard-sized products, each window is produced based on the exact requirements of the building opening.

An incorrect measurement can result in:

• Installation delays
• Additional site modifications
• Waterproofing problems
• Poor window operation
• Increased project costs

For this reason, accurate site measurement is one of the most important steps before manufacturing aluminium windows and doors.

At MEICHEN Windows & Doors, we work with builders, installers and project teams to ensure window specifications are confirmed before production.

Why Accurate Window Measurements Matter

A window opening is not only about width and height.

A successful installation also depends on:

• Opening accuracy
• Wall construction
• Frame positioning
• Flashing requirements
• Installation tolerances

Correct measurement helps ensure:

• Proper fit
• Smooth operation
• Effective sealing
• Long-term performance

Understanding Window Opening Terminology

Before measuring, it is important to understand common construction terms.

Rough Opening

The rough opening is the structural opening prepared for window installation.

It may include:

• Timber framing
• Steel framing
• Masonry openings
• Prepared building apertures

The manufactured window size is usually designed to suit the opening while allowing installation tolerance.

Finished Opening

The finished opening refers to the completed visible opening after internal and external finishes are considered.

This may be affected by:

• Plasterboard
• Cladding
• Brickwork
• Internal reveals

Frame Size

The frame size refers to the actual manufactured window dimensions.

This is different from the opening size and must be confirmed with the window manufacturer.

Step 1 – Check the Latest Drawings

Before measuring, confirm:

• Latest architectural drawings
• Window schedules
• Structural changes
• Builder variations

Using outdated information can result in incorrect manufacturing.

Step 2 – Measure Opening Width

Measure the width of the opening in multiple locations.

Recommended checks:

• Top width
• Middle width
• Bottom width

Compare the measurements.

If the opening is uneven, use the smallest dimension as a reference and discuss requirements with the manufacturer.

Step 3 – Measure Opening Height

Measure the height at:

• Left side
• Centre
• Right side

This helps identify:

• Uneven openings
• Construction movement
• Installation challenges

Step 4 – Check Diagonal Measurements

Diagonal measurements help determine whether the opening is square.

Measure:

• Top-left corner to bottom-right corner
• Top-right corner to bottom-left corner

If the diagonal measurements are different, the opening may require adjustment before installation.

Step 5 – Confirm Wall Construction Type

Window installation details depend heavily on the building structure.

Common Australian wall systems include:

Brick Veneer Construction

Consider:

• Brick reveals
• Flashing
• Cavity drainage
• Fixing methods

Timber Frame Construction

Consider:

• Frame fixing locations
• Building movement
• Weatherproofing details

Steel Frame Construction

Consider:

• Fixing requirements
• Structural coordination
• Corrosion protection

Concrete or Masonry Construction

Consider:

• Opening preparation
• Anchoring method
• Waterproofing interface

Step 6 – Check Installation Clearance

Windows generally require appropriate installation tolerances.

These allow for:

• Alignment adjustment
• Building movement
• Sealant application
• Fixing requirements

The required clearance depends on:

• Window system
• Installation method
• Manufacturer recommendations

Step 7 – Confirm Window Orientation

Before manufacturing, confirm:

• Opening direction
• Sliding door configuration
• Left/right handing
• Internal/external opening

Incorrect handing is one of the most common ordering errors.

Step 8 – Confirm Glass Requirements

Before final approval, confirm:

• Glass thickness
• Safety requirements
• Double glazing requirements
• Low-E glass
• Acoustic requirements

Glass selection should align with:

• Building design
• Location
• Australian Standards

Measuring Large Aluminium Doors

Large systems require additional attention.

Examples:

• Sliding doors
• Bifold doors
• Stacking doors

Important checks include:

• Opening width
• Opening height
• Floor level
• Structural support
• Track area
• Access requirements

Large glazed systems require accurate coordination between builder, installer and manufacturer.

Common Measurement Mistakes

Avoid these issues:

Measuring Too Early

If construction changes after measurement, the opening may no longer match the manufactured product.

Measuring Only One Point

Openings can vary.

Always check multiple locations.

Ignoring Wall Conditions

The installation method depends on the surrounding construction.

Forgetting Door Swing Direction

Incorrect configuration can affect usability.

Not Confirming Final Drawings

Always verify against approved documentation.

Australian Standards Considerations

Window measurements and installation should support compliance with relevant requirements.

AS 2047

AS 2047 covers performance requirements for external windows and glazed doors, including:

• Structural performance
• Air infiltration
• Water penetration resistance

AS 1288

AS 1288 relates to:

• Glass selection
• Safety glazing
• Installation considerations

NCC Requirements

Window installation should also consider the requirements of the National Construction Code, including waterproofing and energy efficiency provisions.

Why Choose MEICHEN Windows & Doors?

MEICHEN Windows & Doors provides customised aluminium window and door solutions for Australian projects.

Our support includes:

• Technical consultation
• Custom manufacturing
• Project coordination
• Performance glazing options
• Quality inspection

Suitable for:

• Residential builders
• Architects
• Developers
• Renovation projects

Frequently Asked Questions

Can builders measure windows themselves?

Yes, experienced builders can measure openings, but measurements should follow the manufacturer’s requirements and installation guidelines.

Should the window size equal the opening size?

No. The manufactured window size usually requires appropriate installation tolerance. The final dimensions should be confirmed with the window supplier.

What happens if the window opening is not square?

The opening may need adjustment before installation, or the manufacturer may recommend a suitable solution depending on the tolerance.

When should windows be measured?

Measurements are usually confirmed after openings are sufficiently prepared and before final manufacturing approval.

Why are custom window measurements important?

Accurate measurements help ensure correct installation, weather performance, smooth operation and reduced construction delays.

Conclusion

Accurate measurement is the foundation of successful custom aluminium window installation.

Before ordering windows, builders should confirm:

• Opening dimensions
• Wall construction
• Installation requirements
• Glass specifications
• Window configuration

Careful preparation helps ensure that aluminium window systems perform as designed and integrate successfully with the building structure.

MEICHEN Windows & Doors supports Australian builders, architects and homeowners with customised aluminium window solutions manufactured for project-specific requirements.