Assess and measureWe check your joinery type and confirm the best retrofit method.
Retrofit double glazing
Upgrade to double glazing without having to replace all of your joinery. We replace your existing single glazing with high-performance double glazed units while preserving your current aluminium or timber joinery. The look of your frames stays largely the same, but your home feels warmer, drier, quieter and more comfortable year round.
Master Glazier
Family owned
Bay of Plenty based
Why upgrade to double glazing?
Double glazing is one of the most noticeable comfort upgrades you can make.
Key benefits
Retains more heat inside and can reduce heating costs
Warmer in winter and cooler in summer
Reduces visible condensation and moisture on windows
Helps reduce outside noise
Retrofit is a quick, straightforward upgrade compared to full replacement
Can enhance the resale and appeal of your home
Retrofit double glazing vs full window replacement
Retrofit is ideal if your frames are in good condition and you want better performance without the cost of full new joinery.
Retrofit double glazing
Keeps existing aluminium or timber frames
Replaces the glass with sealed double glazed units
Minimal visual change to your joinery
Full replacement (new joinery)
New frames and glass throughout
Higher cost, bigger change to the look
Often chosen when frames are beyond repair or you want a full style change
Aluminium retrofit
Retrofit double glazing is a cost-effective way to upgrade window performance without replacing the entire frame.
We remove the existing single glass and replace it with a factory sealed double glazed unit. To create space for the new unit, we replace the existing aluminium bead with a new profile that is colour matched to your current joinery.
Sliding doors: adapters may be required depending on age, but upgrading them is usually still straightforward.
Compatibility: our retrofit systems work with most aluminium joinery. It’s rare we can’t retrofit, and the exceptions are typically some early 1970s systems. If you’re unsure, send us photos and we’ll advise.
Timber retrofit
Timber is a strong natural insulator, so if your timber joinery is in good condition it’s often worth keeping.
Our timber retrofit process replaces the thermally inefficient single glazing with a new factory sealed double glazed unit. We rebate the existing timber frame to create space for the new unit and use new timber beads to secure it in place.
Draft sealing (recommended): older timber windows can have gaps, so we often recommend adding new draft seals to reduce unwanted airflow and heat loss.
Important: if we find rot beyond repair, we’ll let you know before proceeding.
Retrofit Double Glazing FAQs
What is retrofit double glazing?
It replaces existing single glazing with factory sealed double glazed units while reusing your existing frames.
Can you retrofit into aluminium joinery?
Yes. In most cases we replace the glazing bead with a new colour-matched profile to allow space for the double glazed unit.
Can you retrofit into timber joinery?
Yes, where the timber is in suitable condition. We rebate the frame to fit the new unit and secure it with new timber beads.
Will retrofit reduce condensation?
Yes. Double glazing reduces visible condensation on windows and helps create a drier home.
Does double glazing reduce noise?
Yes. Double glazing can help reduce outside noise, improving comfort.
Can you retrofit sliding doors?
Often, yes. Depending on the age of the system, adapters may be needed, but upgrading is usually straightforward.
More questions? See all Retrofit Double Glazing FAQs
Why choose The Glass Guys?
Choosing the right team matters because retrofit needs correct measuring, the right system, and a clean finish.
We keep what’s worth keeping
If your existing joinery is in good condition, retrofit lets you upgrade performance without the cost of full replacement.
Advice for both aluminium and timber
We’ll recommend the best approach for your joinery type and flag any issues early, especially with older timber frames.
Comfort outcomes you’ll notice
Warmer in winter, cooler in summer, less condensation, and a quieter home.
Clean workmanship, tidy finish
We take care of your home during install and leave it neat when we’re done.
