Retrofit Double Glazing vs uPVC Joinery With Double Glazing - Misc. NZ
Retrofit Double Glazing vs uPVC Joinery With Double Glazing

Retrofit Double Glazing vs uPVC Joinery With Double Glazing

Have you decided to double glaze your windows and wonder if you should retrofit or change the whole window frame to uPVC joinery? If you don’t want such a significant change, you can retrofit your timber or aluminium joinery with new double glazed windows. However, if you want the full benefits of double glazed windows, you can also put in uPVC joinery with your new glass, which will change the look of your home more drastically.

Words by Eco Doors & Windows

Eco Doors and Windows explores the pros and cons of each method in this blog, so you can make an informed decision on what double glazing option fits your personal needs!

Retrofitting new double glazed units into your existing timber or aluminium joinery



  • Retrofitting is a great way to upgrade the windows and doors in your home if you don’t want to spend a significant amount of money on your renovations and want to maintain the look of your home. The double-glazed glass and installation cost is the only purchase you will need to make.

Faster lead Time and Quicker Install

  • As the job is smaller than changing the whole joinery, your home’s comfort will improve quickly, and you won’t need to spend a significant time planning the process.

Retain The Look Of Your Home

  • If you want your home to look the same with your double glazed windows as it did with your original glass, retrofitting is the best option for you. The aluminium and timber surroundings, such as sills, facings and reveals, remain, so your home will look exactly the same as previously. If you are attached to your home’s current design, we suggest you choose the retrofitting option.

Less Invasive

  • Retrofitting is a minor renovation process, as all your frames stay in place. Your home won’t be exposed to environmental factors for a long time because no walls need to be opened.


Timber and Aluminium Issues

  • Not changing your old timber and aluminium means that they might still cause you some trouble. For example, timber windows can rot and warp, and aluminium ones get condensation and let heat out often.

Not Sealing Properly

  • Keeping your original joinery likely won’t seal your windows and doors as well as uPVC joinery would, meaning that you could continue getting drafts around your windows. It is very challenging to retrofit double glazed glass without any leaks.

High Maintenance

  • Timber joinery needs to be maintained regularly with painting your sills and frames often. You will need to check for any signs of rotting or warping periodically. Ensuring that your home looks great on the outside will stay a high maintenance job!

What to be mindful of

If you select retrofitting for your double glazing, ensure that your glass has a minimum of 10mm gap between the panes. If the gap is any smaller, you won’t get higher thermal performance than with a single glazed glass. This can become an issue, especially with older and thinner aluminium frames.

uPVC Joinery with Double Glazing - Pros

Thermally Efficient 

  • uPVC joinery with double glazing is the most thermally efficient option on the market. This type is specially made for even the most robust New Zealand environments with high winds and rain. It seals 100%, so you won’t feel any wind gusts again when sitting near your windows. You can say goodbye to condensation by preventing any cold air from getting into your home. 

Low Maintenance

  • uPVC frames are extremely low maintenance. They only need to be cleaned every few months with warm soapy water, and you won’t need to check for any rotting or warping regularly. uPVC joinery stays modern looking for a long time and never needs to be painted. Hinges and handles should be lubricated every four to six months to ensure they function optimally.

Large Double Glazed Options

  • No matter what sized double glazed windows you are looking for, uPVC windows come with a range of different functions and sizes. The 24mm total thickness allows for a 16mm air gap between the two panes, ensuring that your home is fully protected against outside environmental factors, regardless of the window’s size.

Modern Look

  • uPVC joinery has a modern look with sleek lines. At Eco Doors and Windows, we can even manufacture different coloured joinery, so it perfectly fits your current home’s design. This option will add significant value to your property by removing any old joinery that doesn’t work well anymore.

Retain Your Homes Character

  • Even though uPVC windows have a new and modern look, they don’t look much different from timber or aluminium. This means you can retain the character of your home while enjoying all the benefits of this option.

uPVC Joinery with Double Glazing - Cons

More Expensive

  • Changing both the glass and the joinery of your windows and doors can be relatively expensive, especially if you are looking for large surfaces. If you don’t want to spend a significant amount on the renovation process, retrofitting may be a better option for you.

Longer Lead Time and Installation

  • If you are looking for a quick solution, replacing the complete joinery and windows may not be the right option for you. It can take an extended time until we get your custom-sized windows and joinery ready for your home. The installation also takes longer, which means that it will take some time until you can enjoy the comfort of double glazing and uPVC joinery.

More Invasive

  • Replacing whole windows, doors, and joinery can be an invasive process, which results in the installation taking longer than retrofitting would. However, our team strives to finish the job as quickly as possible to provide you with the benefits of uPVC windows.
  • uPVC joinery with double glazing is an excellent option if you want the full benefits of modern windows, including warmth, quiet, secure, and eco-friendly homes. Eco Doors and Windows are experts in uPVC joinery, and we have a wide range of functions and sized glasses available for your needs.
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