Aluminium Insert vs Timber Retrofit Double Glazing in Wellington

By Wellington Glass & Mirror

If you live in Wellington, chances are your home has older timber joinery or original framing that is starting to age. When planning a window upgrade, many homeowners compare aluminium insert vs timber retrofit double glazing to find the best option for improving comfort and energy efficiency.

Both are affordable options for improving comfort, energy performance, and ease of use. Understanding the difference can help you choose the right upgrade for your home, budget, and long-term plans.

Here is an easy breakdown of how each option works.

timber retrofit — Aluminium Insert Windows

What Are Aluminium Insert Windows?

Aluminium insert windows are a clever upgrade designed to fit new double-glazed aluminium frames and windows directly into your existing timber surrounds. The original timber surround fitted into the wall of your house, into which the timber joinery is fitted, remains in place, and the aluminium insert is installed inside this. This means the wall cavity and weather sealing around your windows are undisturbed, and installation is fast with minimal disruption to you and your family.

Aluminium inserts for Wellington homes provide a fresh, modern, low-maintenance alternative without the cost or disruption of removing the entire window frame.

Why Homeowners Choose Double-Glazed Aluminium Inserts

Understanding the differences between aluminium insert vs timber retrofit upgrades helps you choose the right solution for your joinery.

Gives a clean, modern aluminium finish
Markedly improves thermal performance and reduces maintenance
New windows open, close and seal perfectly, minimises drafts and noise
Retains existing timber surrounds while removing old, worn sashes
Faster installation than most joinery replacement options
It’s easy to change window size and configuration within each frame
Works well in most Wellington homes with older timber joinery.

Inserts are ideal when your timber surrounds are still solid but the glass and sashes are old, draughty, or high maintenance.

Timber single glazed windows — After – Aluminium Insert Windows

Two types of aluminium profiles available to choose from: Thermal (warm) and non-Thermal (cool). Thermal aluminium inserts have an insulating thermal ‘break’ built into the joinery that reduces conduction of heat and cold from the inside and outside surfaces of the window frame. The thermal break markedly improves insulation and reduces condensation on the joinery as well as the glass, increasing the overall thermal performance of your windows. Non-Thermal profiles are less insulating but lower cost.

What Is Timber Retrofit Double Glazing?

Timber retrofit double glazing is the process of upgrading existing timber joinery by removing old single glass and putty, refurbishing the sashes and fitting modern double glazing using timber beads.

This preserves and reuses your current timber surrounds and joinery, upgrades the glass to modern double-glazing, and provides an opportunity to refurbish your timber, paint, hinges, hardware, fitment and weather seals to significantly improve comfort and energy efficiency. Timber beads replace old putty, reducing maintenance.

Why Homeowners Choose Timber Retrofit

The original character and appearance of homes is preserved
Existing joinery is refurbished, rehung and refitted to open and close properly, with options for fitting new hardware, draught and weather seals
Comfort and thermal efficiency are markedly improved with modern Low E glass
Timber is a superb insulator, better than Thermal aluminium, and is a natural, sustainable resource
Window sizes and configurations can be changed
Character features like timber grain, lead-lights, double-hung windows can be restored and preserved
Hazards such as asbestos putty and lead paint can be completely removed

Timber retrofit is the most cost-effective way to improve the comfort and energy efficiency of your home without changing your joinery profile.

Learn More “What is Retrofit Double Glazing”

Which Option Is Right for Your Home?

Choosing between aluminium inserts and timber retrofit depends on the condition of your existing joinery and the new look you want to achieve.

Choose Aluminium Inserts If:

You have older timber joinery and want a modern aluminium look without the disruption and expense of full joinery replacement
You want improved comfort and energy efficiency and reduced maintenance
You want a cost-effective solution for double glazing and changing window configuration
You want to replace your old timber joinery without disturbing the surrounding timber frame
You want speed and minimal disruption during installation

Choose Timber Retrofit If:

You want modern double glazing AND to keep the existing character and appearance of your home
You prefer the look and feel of timber
You want to refurbish and keep your existing timber sashes
You want to refurbish and keep existing lead-light or double hung windows
You value the natural superior insulating properties of timber

If you are unsure, our team can assess your joinery and expertly guide you to make the best choice for you and your home. Learn more on our Request a Quote page.

How Do Aluminium Inserts Compare with Timber Retrofit?

Many Wellington homeowners compare aluminium insert vs timber retrofit options when planning a double glazing upgrade. Both options result in double glazed windows, but they differ in performance, appearance, and installation.

What About Double-Glazing Glass Options?

Both aluminium inserts and timber retrofit allow you to upgrade to a range of glass types, including our SuperTherm™ high-performance range, designed to optimise comfort, solar control, privacy, noise and energy efficiency in Wellington homes.

Available Glass Options

SuperTherm™ Cool – insulate when it’s cold and reduce overheating, glare and furniture fading from the sun when it’s hot, improving comfort and energy efficiency year-round.
SuperTherm™ Warm – insulate when it’s cold and retain heat from the sun in cooler climates or areas of your home.
SuperTherm™ Warm + Hush Glass – combines SuperTherm™ Warm with acoustic laminated safety glass (“hush” glass) to optimise heat retention and maximise UV protection and noise reduction.
SuperTherm™ Protect – combines SuperTherm™ Cool with acoustic laminated safety glass (“hush” glass) to maximise insulation, solar radiation control, UV protection and noise reduction.
SuperTherm™ Custom – combines any combination of SuperTherm™ double-glazing as well as tinted and privacy glass options in different rooms or aspects of your home to optimise comfort and energy efficiency, tailoring the amount of light, heat, noise and radiation that enters your home with your privacy requirements to create an optimal living environment.

Learn more about our Supertherm™ Range.

Image Source: RetroGlaze®- Learn more about RetroGlaze here

For official guidance on glass and glazing standards in NZ including safety and wind loading, see NZS 4223 – Glazing Standards.

How to Know For Sure

If you are still deciding between aluminium insert vs timber retrofit double glazing, our team can assess your home and guide you toward the best option. The best way to decide on the ideal joinery and double-glazing option for your home is to book a free measure and quote from a RetroGlaze® Double Glazing Consultant to assess:

Your needs, goals and priorities
The type and condition of your existing joinery and frames
Whether timber retrofit is suitable
Whether aluminium inserts will fit properly
The ideal glass option or combination for your home that meets your needs
Long-term performance, maintenance and home value considerations

As Wellington’s trusted RetroGlaze® Partner, we provide expert, clear advice to help you can make an informed decision with confidence.

Ready to Upgrade Your Windows?

Whether you choose aluminium inserts or timber retrofit, you’re guaranteed improved comfort and energy efficiency all year round.

If you would like expert advice on which option is right for your home, our team can design a solution that suits your joinery, your home, and your lifestyle.

👉 Book your free measure and quote today.

FAQs

What is the difference between aluminium inserts and timber retrofit double glazing?

Aluminium inserts replace old timber sashes with new double glazed aluminium frames while keeping the existing timber surround. Timber retrofit keeps your entire timber joinery, refurbishes it, and upgrades the glass to modern double glazing.

Which option gives better insulation?

Both provide excellent insulation when paired with SuperTherm™ glass. Timber has natural insulating properties, while aluminium inserts rely on thermal breaks and modern sealing systems to improve performance.

Can I change my window configuration with either option?

Aluminium inserts allow for configuration changes such as removing transoms or mullions. Timber retrofit can also adjust layout but is typically used to preserve existing profiles and character details.

Which option is more cost-effective?

Both are cost-effective compared to full replacement. Aluminium inserts are ideal when you want a modern look. Timber retrofit is ideal when you want to preserve your timber joinery and character features.

How do I know which option is right for my home?

Book a free measure and quote. Our team will assess your joinery, confirm whether inserts or timber retrofit is suitable, and recommend the best SuperTherm™ glass option based on your home’s needs.