How to Double Glaze Your Existing Windows with Retrofit Secondary Glazing

Double Glazing Existing & Old Windows

Our systems are designed and tested to fit existing glazing in your home or office. Magnetite can double glaze existing and old windows while at the same time retaining the character of period and heritage properties. Our systems have minimal impact to the inside of the property and will not affect the aesthetic of a window from outside. Magnetite’s optical grade acrylic and Soundtite’s clear laminated glass will maintain crystal clear views through your windows. Magnetite’s retrofit double glazing systems are an ideal thermal insulation and soundproofing solution for strata unit and heritage listed property as well as newer, modern buildings. With a range of products, Magnetite can provide the best acoustic and thermal solution for your home or office.

The installation of Magnetite’s systems is relatively quick as no structural building modifications are required. By double glazing existing windows, we reduce installation times and minimise disruption to your home or business. This saves you money and stress as well as helps the environment by minimising landfill created by discarded old windows.

Magnetite helps to make your home or office more comfortable without the hassle of replacement windows or door. Double glazing existing windows and doors can achieve all the benefits of traditional double glazing without the cost and hassle of replacement windows.

How Magnetite solutions work?

Our secondary glazing systems are retrofitted to the inside of existing windowsill, creating optimal air cavity to provide the best results for noise reduction and thermal insulation.

Installation of Magnetite discreet subframe allows an acrylic panel to be magnetically attached to the inside of the existing windowsill. Magnetic seals ensure a secure and airtight seal around the inside of the window, minimising draughts. The new Magnetite retrofit double glazing creates an air cavity between your existing window and your Magnetite panel which acts as an insulation barrier against noise and temperature. Depending on the configuration of the existing window, we can adjust the size of the air cavity to maximise acoustic insulation, thermal insulation or both. Watch how Magnetite works

Similarly, Soundtite secondary glazing system can be designed to slide horizontally or vertically to match your existing sliding window or door. All sashes can be made to slide for ease of cleaning and operation.

Double glaze existing windows in your home or office for soundproofing and year round thermal comfort. Call or email us today for a free window assessment.

Our Products

Magnetite®

Retrofit double glazing for acoustic and thermal insulation

Our proven magnetic secondary glazing system enhances the performance of your current windows, doors, skylights, and glass areas by creating an insulating air cavity. This barrier reduces noise and stabilises indoor temperature, resulting in a more comfortable environment for rooms, homes, and buildings.

Sealtite

Acoustic and weather seals

Enhance the insulation of your home or office with our selection of acoustic and weather seals. These seals improve the performance of your existing windows and doors by using draught-proofing strips that are suited to any style. Sealtite weather seals not only reduce noise levels but also enhance thermal comfort, all while being custom fit for immediate soundproofing benefits. Enjoy easy operation with this effective solution.

Soundtite

Soundproofing for existing windows and doors

A secondary aluminium system that is specially designed to reduce noise through an existing sliding window or sliding door. The system can be designed to slide horizontally or vertically to match the existing aluminium window function and design.

Submit your enquiry and we will get back to you within 1 business day.

FAQs

Can I add retrofit secondary glazing to timber/wooden sash windows?

Yes, absolutely. Wooden sash windows are where retrofit secondary glazing performs best. Because retrofit glazing fits inside your window reveal, the original timber frame, sashes, and glass stay completely untouched. Your heritage features are fully preserved. Retrofit secondary glazing on timber sash windows dramatically improves thermal comfort (up to 70% better heating efficiency) and reduces noise (up to 70% reduction) without compromising the character of period homes. This is ideal for Federation cottages, Victorian terraces, and Edwardian homes. The retrofit system is invisible from outside.

Does retrofit secondary glazing work on aluminium window frames?

Yes. Retrofit glazing works on aluminium, timber, and PVC frames. Aluminium frames are common in modern Australian homes. Magnetic seals (in Magnetite products) create a secure, airtight fit on aluminium frames without requiring frame modification. Installation is straightforward because aluminium frames are rigid and flat. The magnetic system creates an insulating air cavity that dramatically improves thermal performance—important for aluminium, which conducts heat poorly. If you have aluminium windows and your home feels cold in winter or hot in summer, retrofit secondary glazing is an effective solution.

Will retrofit glazing damage my existing windows?

No. Retrofit secondary glazing is completely non-invasive. It fits over your existing frames without modification, drilling, or permanent attachment (depending on the system). Your original windows remain intact and unchanged. In fact, retrofit glazing protects your existing windows from direct weather exposure, potentially extending their lifespan. If you ever want to remove the retrofit system (e.g., if you move house or change your mind), your original windows are completely unaffected. This makes retrofit glazing ideal for rental properties and temporary living situations—fully reversible comfort improvement.

How is retrofit secondary glazing different from traditional replacement windows?

Retrofit secondary glazing (also called secondary glazing) adds a new glazed layer inside your existing window reveal without removing your current frames. Replacement windows remove the entire frame and install new double-glazed units. Retrofit is faster (1-2 days per room vs weeks), less disruptive, costs 40-60% less, and preserves period features. Performance is equivalent or better—the wide air cavity in retrofit glazing (100-125mm) reduces noise more effectively than many narrow-gap replacement windows. Replacement windows are better if your frames are deteriorating or you want modern styling. For comfort, noise reduction, and cost-effectiveness, retrofit secondary glazing is the superior choice for most Australian homes.

Can I remove retrofit secondary glazing if I move house?

Yes. Retrofit secondary glazing systems are designed to be removable. You can take the panels with you if you move, leave them for the next occupant, or remove them without damaging your original windows. This makes retrofit glazing ideal for rental properties—improve tenant comfort and reduce heating/cooling costs without permanent modification. Tenants benefit from lower utility bills (happier tenants), and landlords improve property value. For owner-occupiers planning to move in 5-10 years, retrofit glazing offers all the comfort benefits without permanent commitment.

Glazing Type	Cooling Stars	Heating Stars	Cool%	Heat%	Uw	SHGC
Single glazed 3mm clear glass*					7.4	0.77
Single glazed 3mm clear glass & 4.5mm Magnetite			35%	59%	2.9	0.67

Glazing Type

Cooling Stars

Heating Stars

Cool%

Heat%

SHGC

Single glazed 3mm clear glass*

7.4

0.77

Single glazed 3mm clear glass &
4.5mm Magnetite

35%

59%

2.9

0.67

Glazing Type	Cool%	Heat%	Uw	SHGC
Single glazed 3mm clear glass*	20%	28%	5.5	0.69
Single glazed 3mm clear glass & 4.5mm Magnetite	37%	61%	2.6	0.66
Single glazed 3mm clear glass with Solartite** and 4.5mm Magnetite	76%	45%	1.8	0.20

Glazing Type

Cooling Stars

Heating Stars

Cool%

Heat%

SHGC

Single glazed 3mm clear glass*

20%

28%

5.5

0.69

Single glazed 3mm clear glass &
4.5mm Magnetite

37%

61%

2.6

0.66

Single glazed 3mm clear glass with
Solartite** and 4.5mm Magnetite

76%

45%

1.8

0.20

Glazing Type	Cooling Stars	Heating Stars	Cool%	Heat%	Uw	SHGC	AI
Double Glazed 3mm clear glass/12mm air gap/3mm clear glass IGU (Insulated Glass Unit)*			40%	55%	3.0	0.61	5.0
Single glazed 3mm clear glass & 4.5mm Magnetite			37%	61%	2.6	0.66	0.5

Glazing Type

Cooling Stars

Heating Stars

Cool%

Heat%

SHGC

Double Glazed 3mm clear glass/12mm air
gap/3mm clear glass IGU (Insulated Glass Unit)*

40%

55%

3.0

0.61

5.0

Single glazed 3mm clear glass &
4.5mm Magnetite

37%

61%

2.6

0.66

0.5

Glazing Type	Cooling Stars	Heating Stars	Cool%	Heat%	Uw	SHGC	AI
Double Glazed 5mm Supertoned glass/6mm air gap/5mm clear glass IGU (Insulated Glass Unit)*			54%	425%	3.30	0.461	5.0
Single glazed 3mm glass Solartite** and 4.5mm Magnetite			73%	38%	2.4	0.19	0.5

Glazing Type

Cooling Stars

Heating Stars

Cool%

Heat%

SHGC

Double Glazed 5mm Supertoned glass/6mm
air gap/5mm clear glass IGU (Insulated Glass Unit)*

54%

425%

3.30

0.461

5.0

Single glazed 3mm glass Solartite**
and 4.5mm Magnetite

73%

38%

2.4

0.19

0.5

Noise Reduction Technical Data and Results

Proven Results

Noise pollution is one the biggest problems faced in the cities today, particularly in a high-density living. Unwanted noise can be responsible for sleep loss and lack of concentration. This can lead to a deterioration of health through increased stress levels, headaches, high blood pressure and loss of hearing.

Noise penetrates windows through leaky seals or vibrations through the window structure. To reduce noise, a window should minimise air infiltration, hold enough weight to limit vibration and allow a large air cavity. This cavity, or air gap, is the key to secondary glazing.

Expert Advice:

CSIRO Research by John Davy shown an air cavity can effectively enhance sound insulation performance. The larger the air cavity the more noise the window system can reduce. Results show a wide air gap of 100-125mm will improve sound insulation by an average of 7dB(A) more than windows with a narrow gap of 8-13mm.

Window or Glass Door Type	Total Glass Thickness (mm)	Air Cavity Thickness (mm)	Sound Insulation (dB)
Single Glaze 3mm	3	0	23
Single Glaze 6mm	6	0	27
Double Glaze Narrow Gap	9-12	8-13	31
Double Glaze Wide Gap	9-12	100-125	38

Window or Glass Door Type

Total Glass Thickness (mm)

Air Cavity Thickness (mm)

Sound Insulation (dB)

Single Glaze 3mm

Single Glaze 6mm

Double Glaze Narrow Gap

9-12

8-13

Double Glaze Wide Gap

9-12

100-125

The human ear is less sensitive to low frequency sound. According to a study released by the CSIRO, the human ear needs a change of 3dB to detect a difference in noise levels and the human ear perceives a change of 10dB as a doubling or halving of the noise level.

If you double the thickness of glass in a window the noise level will decrease by 3dB the least amount possible to make a difference. If the glass is laminated there is no perceived difference in noise reduction.

National Acoustic Laboratory Testing:

Working with the principles of noise transfer, Magnetite® and Soundtite are designed for high performance, which is achieved by combining air tight seals with the ability to maximize an air cavity and the flexibility to vary glazing thickness to suit. Magnetite® is excellent at reducing general noise such as busy roads, commuter trains and noisy neighbours. Whereas, Soundtite works well to combat low frequencies noise such as garbage truck, freight trains or airplane during take-off and landing.

Test Code	Material Tested	Rw*	Improvement
ATF 707 (test window)	Aluminium sliding window, 3mm float glass with mohair seals	23	N/A
ATF 709	Test window, 100mm air gap and Magnetite System (4.5mm acrylic panel)	35	52%
ATF 1507	Test window, 100mm air gap and Magnetite System (10.0mm acrylic panel)	39	70%
ATF 817	Test window, 100mm air gap and Soundtite (6.38mm laminated glass)	41	78%

Test Code

Material Tested

Rw*

Improvement

ATF 707 (test window)

Aluminium sliding window, 3mm float glass with mohair seals

N/A

ATF 709

Test window, 100mm air gap and Magnetite System (4.5mm acrylic panel)

52%

ATF 1507

Test window, 100mm air gap and Magnetite System (10.0mm acrylic panel)

70%

ATF 817

Test window, 100mm air gap and Soundtite (6.38mm laminated glass)

78%

*The Weighted Sound Reduction Index (Rw) is a measure for sound insulation performance of a single building element such as windows. The higher the Rw rating, the better the sound insulation.

How to Double Glaze Your Existing Windows with Retrofit Secondary Glazing

Double Glazing Existing & Old Windows

How Magnetite solutions work?

Our Products

Magnetite®

Retrofit double glazing for acoustic and thermal insulation

Sealtite

Acoustic and weather seals

Soundtite

Soundproofing for existing windows and doors

Submit your enquiry and we will get back to you within 1 business day.

FAQs

Can I add retrofit secondary glazing to timber/wooden sash windows?

Does retrofit secondary glazing work on aluminium window frames?

Will retrofit glazing damage my existing windows?

How is retrofit secondary glazing different from traditional replacement windows?

Can I remove retrofit secondary glazing if I move house?

The Window Energy Rating Scheme (WERS) Thermal Performance

Aluminium Frame Windows

Timber Frame Windows

Magnetite vs Traditional Double Glazing – What the experts says