Posted September 21, 2026
Road noise, neighbours or early-morning traffic can make a bedroom or living room less comfortable. In many Christchurch homes, especially older villas and bungalows, the same windows that feel cold or draughty in winter can also let in more outside noise than you would like.
When considering retrofit double glazing, it is worth thinking about noise at the same time. Double glazing can help, but the type of glass matters. For many residential retrofits, laminated safety glass is a practical step up when a quieter room is one of the main goals.
Not every double-glazed unit performs the same way when it comes to outside noise. The right glass depends on the level and type of noise, as well as the condition of the existing windows.
Standard double glazing can help reduce outside noise while also improving warmth, comfort and condensation control.
For homes where traffic or neighbourhood noise is noticeable but not severe, a standard retrofit double-glazing solution may be enough.
For a broader explanation, see how double glazing reduces noise.
When outside noise is a bigger priority, laminated safety glass can be a useful upgrade.
Laminated glass has a thin layer between the sheets of glass that helps reduce vibration. In practical terms, it can do a better job of softening traffic and other persistent outside noise than standard glass.
Sharp Glass’s test data shows its laminated double-glazed option reducing more sound than a standard double-glazed option.
The figures are best used to compare glass options rather than predict exactly how quiet a room will become. Window frames, seals, walls and insulation all influence the final result.
There are also specialist acoustic glass products available, but these are not always necessary for a standard residential retrofit. They cost more, and the rest of the room can still limit the overall result.
Better glass can help, but the complete window still matters.
If a window rattles, has worn seals or does not close properly, upgrading the glass alone may not solve the problem. Sound can travel through gaps around the window, while the walls and insulation surrounding it can also affect how much outside noise reaches the room.
This is especially important in older Christchurch villas and bungalows, where the condition of timber joinery can vary considerably.
Sharp Glass assesses the existing window and joinery before recommending an upgrade rather than looking at the glass in isolation.
Different glass types can be selected window by window.
For example, if two street-facing bedrooms are affected by traffic noise but rooms at the back of the house are already relatively quiet, laminated safety glass could be used in those bedrooms while standard double glazing is used elsewhere.
For many homeowners, this is a more practical use of budget than automatically specifying the same glass throughout the whole house.
Costs vary by window and home, but there are useful ballpark figures.
Standard retrofit double glazing is often around 400–500 for each separate double-glazed unit, while Xcel Low E double glazing is generally around 500–600 per unit. One window can contain more than one unit.
Upgrading a suitable unit to laminated safety glass may add roughly 15–21 per unit when upgrading from toughened safety glass and around $60 per unit when upgrading from annealed glass.
The final quote will still depend on window size, joinery condition, access and the number of units.
Using laminated glass only in the rooms where noise matters most can also help keep the overall project cost practical.
For a fuller breakdown, see noise-reducing glass costs in Christchurch.
Yes, where the existing joinery is suitable.
Retrofit double glazing in Christchurch allows existing timber or aluminium joinery to be retained. Sharp Glass checks its condition first, then recommends the glass that suits each window.
This is particularly relevant in Christchurch villas, bungalows and character homes where homeowners want better comfort without replacing existing joinery that is still in good condition.
Our guide to double glazing villa and character windows explains what is practical.
Acoustic ratings are useful for comparing one glass option with another, but they do not tell you exactly how quiet a bedroom or living room will feel once the glass is installed.
For most homeowners, the more useful question is which glass option makes sense for the noise problem in that room.
No. Double glazing can reduce outside noise, but it will not make a room completely soundproof.
The final result depends on the glass, window frames, seals, walls, insulation and other possible paths for sound to enter the room.
If you want to improve noise without immediately changing the glass, see the cheapest ways to reduce noise through windows.
The goal is not to buy the most expensive or highest-rated glass available. It is to match the glass to the problem.
If outside noise is one of the reasons you are changing your windows, tell Sharp Glass early. We can check the existing windows and joinery, look at which rooms are affected and recommend a practical glass option for each window.
Sharp Glass has worked on Christchurch homes since 1973, so the advice starts with the house you already have, not a one-size-fits-all answer.
