What is secondary glazing?

Secondary glazing involves fitting an additional glazed panel to the inside of an existing window. The original window remains in place, while the secondary panel creates an extra barrier against heat loss, draughts and outside noise.

Does secondary glazing work?

Yes. When correctly specified and professionally installed, secondary glazing can improve the thermal and acoustic performance of existing windows. The results depend on the condition of the original window, glass specification, air gap and quality of installation.

How much does secondary glazing cost?

The cost depends on the size and number of windows, the opening style, glass specification and installation requirements. As each unit is made to measure, a survey is usually required before an accurate quote can be provided.

Is secondary glazing worth it?

Secondary glazing can be worthwhile if you want to improve comfort and reduce outside noise without replacing your existing windows. It is particularly suitable for period properties, listed buildings and homes where retaining the original windows is important.

Does secondary glazing stop condensation?

Secondary glazing may help reduce condensation by improving the internal surface temperature of the window. However, condensation can also be caused by high humidity or insufficient ventilation, so the underlying cause should be considered before installation.

Can secondary glazing reduce outside noise?

Yes, the additional pane and the space between the two windows can help reduce noise transmission. The level of improvement will depend on factors such as the glass specification, size of the air gap and type of external noise.

Can secondary glazing be fitted to sash windows?

Yes. Vertical sliding secondary glazing is particularly suitable for many traditional sash windows. It can provide access to the original window while helping preserve its character and appearance.

Can I still open my windows?

Yes. Secondary glazing is available in horizontal sliding, vertical sliding, hinged and lift-out configurations, allowing continued access to the original window for ventilation and cleaning.

Is secondary glazing suitable for listed buildings?

Secondary glazing can be a suitable option for listed buildings because it is installed internally and allows the original windows to remain in place. However, you should consult the relevant local planning authority to confirm whether listed building consent is required.

Is secondary glazing better than double glazing?

Neither option is automatically better for every property. Secondary glazing retains the original window, whereas double glazing normally replaces it. The most appropriate choice will depend on the building, your budget and whether thermal performance, noise reduction or preservation of original features is the priority.

Secondary Glazing Manchester

Product type	U-Value Primary Window	U-Value Primary + Secondary Window	U-Value Improvement
Slimline Hinged Unit	4.7 W/m²K	1.4 W/m²K	70%
Horizontal Sliding Unit	4.7 W/m²K	1.5 W/m²K	68%
Vertical Sliding Unit	4.7 W/m²K	1.5 W/m²K	68%

Feature	Secondary glazing	Double glazing	Triple glazing
How it works	A separate glazed panel is installed inside the existing window	Two panes of glass are fitted within one sealed unit	Three panes of glass are fitted within one sealed unit
Existing window	Remains in place	Usually replaced	Usually replaced
External appearance	Normally remains unchanged	May change depending on the selected frame	May change depending on the selected frame
Thermal performance	Improves the insulation of existing windows	Strong modern thermal performance	Enhanced thermal performance
Noise reduction	Particularly effective when correctly specified with a suitable air gap	Helps reduce everyday outside noise	Provides additional glazing for improved comfort
Best suited for	Period properties, listed buildings and homes affected by noise	Most modern replacement window projects	Homes prioritising higher levels of insulation
Access and cleaning	Available in sliding, hinged and removable styles	Cleaned as a standard replacement window	Cleaned as a standard replacement window
Installation	Fitted internally without removing the primary window	Requires replacement of the existing window or glazed unit	Requires replacement of the existing window or glazed unit

1Improved Acoustic Insulation

The additional internal pane creates another barrier between your home and the outside environment. This can help reduce noise entering through existing windows, making secondary glazing particularly useful for properties near busy roads, railway lines, flight paths or lively urban areas. The final level of sound reduction will depend on factors including the existing window, glass specification, distance between the panes and quality of installation.

2Enhanced Thermal Performance

Older windows can allow heat to escape and cold draughts to enter your home. Professionally installed secondary glazing adds another insulating layer, helping reduce heat loss and making rooms feel warmer and more comfortable. Depending on the existing window and the secondary glazing configuration selected, thermal performance may be improved by up to 70%.

3A Discreet Internal Appearance

Because the secondary unit is fitted inside the property, it does not normally alter the exterior appearance of the building. Slim frames, suitable colours and made-to-measure configurations help the new panel blend with your existing windows and interior.

4Retain Your Existing Windows

Secondary glazing allows you to improve window performance without removing original frames. It can therefore be a suitable solution for period homes, heritage properties and buildings where retaining original features is a priority.

5Reduced Draughts

A well-fitted secondary glazing system can help limit unwanted air movement around older windows. Reducing cold draughts can make the room more comfortable, particularly during autumn and winter.