DIY Secondary Glazing: Kits, Methods and Cost Savings

What is DIY secondary glazing?

DIY secondary glazing involves fitting a second pane of glazing (usually acrylic or polycarbonate) to the interior side of an existing window using a kit you install yourself. The secondary pane creates an insulating air gap between itself and the original window, reducing heat loss and improving soundproofing without altering the existing window (Energy Saving Trust, 2026).

DIY secondary glazing is significantly cheaper than professional installation (typically £50-£150 vs. £200-£600 per window) and can be fitted by homeowners with basic DIY skills. The main trade-off is aesthetics and longevity: DIY systems may not look as polished as bespoke professional installations and may require replacement or maintenance after 5-10 years.

Secondary glazing is particularly suitable for period properties, listed buildings, and conservation areas where double glazing is not permitted or would compromise the character of the property. For more context, see our guide to secondary glazing for sash windows.

Types of DIY secondary glazing systems

There are four main types of DIY secondary glazing system, each with different installation methods, costs, and performance characteristics.

1. Magnetic acrylic systems

Magnetic secondary glazing uses acrylic or polycarbonate panels mounted on a magnetic frame. The frame adheres to a steel strip fixed around the window reveal or frame. The panel can be removed and replaced quickly without tools, making it ideal for windows you need to open occasionally.

Cost: £80-£150 per window for materials
Installation time: 1-2 hours per window
Tools required: Tape measure, drill, spirit level, hacksaw (to cut steel strip)
Thermal performance: U-value reduction of 30-50% (from ~5.0 W/m²K for single glazing to ~2.5-3.5 W/m²K with secondary glazing)
Acoustic performance: Noise reduction of 5-8 dB with 100mm+ air gap
Suppliers: Magnetite UK, Easyglaze

Magnetic systems offer the best balance of performance, ease of installation, and removability. They are suitable for most window types including sash windows, casements, and fixed lights.

2. Adhesive-fixed acrylic panels

Adhesive systems use acrylic or polycarbonate panels fixed permanently (or semi-permanently) to the window frame or reveal using double-sided tape or adhesive strips. They are the simplest and cheapest DIY option but cannot be easily removed once installed.

Cost: £40-£80 per window for materials
Installation time: 30 minutes to 1 hour per window
Tools required: Tape measure, sharp knife (to cut acrylic if needed)
Thermal performance: U-value reduction of 25-40%
Acoustic performance: Noise reduction of 3-6 dB (less than magnetic due to smaller air gap)
Suppliers: Wickes, Screwfix, Amazon

Adhesive systems work well for windows you rarely or never open, such as fixed lights or windows in spare rooms. They are not suitable for frequently opened windows or windows requiring regular cleaning.

3. Plastic film secondary glazing

Plastic film systems use a thin transparent film (typically PVC or polyethylene) stretched over the window opening using double-sided tape. The film is then heat-shrunk with a hairdryer to remove wrinkles and create a taut surface.

Cost: £10-£30 per window for materials
Installation time: 20-40 minutes per window
Tools required: Scissors, hairdryer
Thermal performance: U-value reduction of 15-25% (thin air gap reduces effectiveness)
Acoustic performance: Minimal (1-3 dB reduction)
Suppliers: Screwfix window insulation kits, 3M, Tesa

Plastic film is a temporary, low-cost solution suitable for winter use only. The film typically lasts one heating season (4-6 months) before needing replacement. It is not suitable for period properties where aesthetics matter, as the film can look visibly cheap and may wrinkle or yellow over time.

4. Hinged or sliding acrylic panels (advanced DIY)

More advanced DIY kits allow you to build hinged or horizontal sliding secondary glazing panels using aluminium or uPVC track systems. These require more time and skill to install but offer professional-level functionality.

Cost: £100-£200 per window for materials
Installation time: 3-4 hours per window
Tools required: Drill, screwdriver, hacksaw, spirit level, silicone sealant
Thermal performance: U-value reduction of 35-50%
Acoustic performance: Noise reduction of 6-10 dB with 150mm+ air gap
Suppliers: Easyglaze track systems, Magistiс Glazing DIY kits

Hinged and sliding systems are best for larger windows or windows you need to open regularly. They require moderate DIY skills and patience to achieve a neat finish.

How to install DIY magnetic secondary glazing (step-by-step)

Magnetic secondary glazing is the most popular DIY option. Here's how to install it on a typical sash or casement window.

What you need

• Magnetic secondary glazing kit (acrylic panel, magnetic strips, steel strips)
• Tape measure
• Hacksaw (to cut steel strip to length)
• Drill and appropriate drill bits for your wall type
• Spirit level
• Pencil
• Screws and wall plugs (usually supplied with kit)
• Cleaning materials (glass cleaner, microfibre cloth)

Step 1: Measure the window opening

Measure the width and height of the window reveal (the recess where the window sits) at three points (top, middle, bottom for width; left, middle, right for height). Use the smallest measurement for each dimension to ensure the panel fits.

Add 10-20mm to each dimension to allow the magnetic frame to overlap the window opening and create a good seal. Most kits provide guidance on overlap dimensions.

Step 2: Order or cut the acrylic panel

Most suppliers cut acrylic panels to your exact measurements. If you need to cut the panel yourself, use a sharp knife and straight edge to score the acrylic deeply (10-15 passes), then snap it along the scored line. Smooth cut edges with fine sandpaper.

For best thermal and acoustic performance, use 4mm or 6mm acrylic. Thicker acrylic performs better but is heavier and more expensive.

Step 3: Fix the steel strip to the window frame or reveal

Cut the steel strip supplied with the kit to match the perimeter of the window opening. Use a hacksaw and mitre the corners at 45 degrees for a neat finish.

Clean the window frame or reveal thoroughly with glass cleaner to remove dust and grease. This ensures the steel strip (which is usually self-adhesive) sticks properly.

If the steel strip is not self-adhesive, drill pilot holes every 150-200mm and screw it to the frame using the screws and plugs supplied. Use a spirit level to ensure the strip is straight and vertical/horizontal.

Step 4: Attach the magnetic strip to the acrylic panel

Peel the backing from the magnetic strip (usually supplied in rolls or pre-cut lengths) and press it firmly onto the back of the acrylic panel around the perimeter. Ensure the strip is flush with the edge of the panel for a good seal.

Some kits use a plastic channel that holds the acrylic and magnetic strip together. Follow the manufacturer's instructions if your kit uses this system.

Step 5: Install the panel

Hold the panel up to the window opening and allow the magnetic strip to snap onto the steel strip fixed to the frame. Check the seal is continuous around the entire perimeter. If there are gaps, adjust the steel strip position or add extra magnetic strip.

The panel should hold firmly but be removable by pulling gently at one corner. If the panel falls off easily, the magnets are too weak or the steel strip is not close enough to the magnetic strip.

Step 6: Test and adjust

Close any curtains or blinds over the secondary glazing and check for draughts by holding your hand around the perimeter on a windy day. If you feel air movement, add draught-excluding foam or brush strip to the steel strip to improve the seal.

Remove and replace the panel several times to ensure it seats correctly each time. Clean the acrylic with a microfibre cloth and acrylic-safe cleaner (avoid glass cleaners containing ammonia, which can craze acrylic over time).

How much does DIY secondary glazing cost compared to professional installation?

DIY secondary glazing saves around 70-85% compared to professional installation. Here's a typical cost comparison for a medium-sized sash window (1200mm × 1400mm):

For a typical Victorian terrace with 8-10 windows requiring secondary glazing, DIY magnetic systems cost around £1,000-£1,500 total vs. £3,000-£6,000 for professional installation. The saving is substantial, but you invest your own time (8-20 hours for a full house) and accept a less polished finish.

For detailed cost breakdowns and quotes, see our guide to secondary glazing costs.

When is DIY secondary glazing suitable?

DIY secondary glazing works well in these situations:

• Budget constraints: You want the thermal and acoustic benefits of secondary glazing but cannot afford professional installation.
• Rental properties: You rent and cannot make permanent alterations. Magnetic systems are removable and leave minimal trace.
• Trial period: You want to test secondary glazing before committing to a professional system. DIY kits are a low-cost way to evaluate performance.
• Simple window shapes: Your windows are rectangular or square with flat reveals. Complex shapes (arched, circular, bay windows) are difficult to fit with DIY kits.
• Low-traffic windows: The windows are in spare bedrooms, studies, or other rooms where you don't need frequent access or perfect aesthetics.

Limitations of DIY secondary glazing

DIY systems have several limitations compared to professional installations:

• Aesthetics: DIY kits rarely achieve the invisible, flush finish of bespoke professional systems. Acrylic panels may be slightly wavy or have visible joints. This matters more in reception rooms and less in bedrooms or service areas.
• Durability: Acrylic scratches more easily than glass and may yellow slightly over 10-15 years if exposed to direct sunlight. Professional aluminium-framed systems with glass panels last 20-30 years with minimal maintenance.
• Complex windows: DIY kits struggle with non-rectangular windows, deep or uneven reveals, or windows with protruding handles or hinges. Professional installers can scribe panels to fit awkward shapes.
• Sound insulation: DIY systems typically achieve air gaps of 50-100mm. Professional systems can achieve 150-200mm gaps in deep reveals, which significantly improves acoustic performance (each doubling of the air gap adds around 3 dB noise reduction).
• Building regulations: If your property requires fire escape windows, DIY secondary glazing must not obstruct the opening. Professional installers understand building regulations and can design compliant systems.

For listed buildings or properties in conservation areas, consult your local planning authority before installing secondary glazing (DIY or professional). Most secondary glazing does not require planning permission because it is internal and reversible, but listed building consent may be needed.

How much energy will DIY secondary glazing save?

DIY secondary glazing can reduce heat loss through windows by 30-50%, depending on the type of system and air gap achieved. For a typical Victorian terrace with single-glazed sash windows, adding DIY magnetic secondary glazing to all windows saves around 10-15% on annual heating bills (Energy Saving Trust estimates, 2026).

For a house using £1,500/year on gas heating, that's £150-£225 saved per year. At a total DIY cost of £1,000-£1,500 for materials, the payback period is 5-10 years. Professional secondary glazing (£3,000-£6,000) has a payback period of 15-30 years at current energy prices, making DIY more financially attractive unless aesthetics or longevity are priorities.

Secondary glazing also reduces condensation on the inner pane, which protects window frames and reduces mould risk in cold weather.

Can you use DIY secondary glazing on sash windows?

Yes. Magnetic and adhesive DIY secondary glazing works well on sash windows, which are common in Victorian and Edwardian terraces. The secondary pane is fitted to the inside face of the window reveal or architrave, leaving the sash mechanism unobstructed.

For best results on sash windows:

• Fit the secondary glazing to the reveal (the recess around the window) rather than directly to the sash frame. This allows the sashes to open and close behind the secondary pane.
• Use magnetic systems so you can remove the secondary pane when you need to open the sashes for ventilation or cleaning.
• If you need to open the sashes frequently, consider a professional lift-out or hinged system instead of DIY, as removing and replacing magnetic panels daily becomes tedious.

For more detail on secondary glazing for sash windows, see our dedicated guide: Secondary Glazing for Sash Windows.

Where to buy DIY secondary glazing kits

DIY secondary glazing kits are available from several UK suppliers. Here are the main options as of May 2026:

Magnetite UK

Magnetite is an Australian company now operating in the UK, offering DIY magnetic secondary glazing kits. Kits include pre-cut acrylic panels, magnetic strips, steel strips, and fixing hardware. Prices range from £120-£180 per window depending on size. Magnetite provides detailed installation videos and telephone support.

Easyglaze

Easyglaze supplies both DIY and professional secondary glazing systems. Their DIY range includes magnetic, adhesive, and track-based systems. Prices range from £80-£200 per window. Easyglaze cuts acrylic to your measurements and ships kits with full instructions.

Screwfix and Wickes

Screwfix and Wickes stock basic polycarbonate sheet and adhesive-fix secondary glazing kits for £40-£100 per window. These are cheaper than magnetic systems but are less sophisticated and usually require you to cut the panels yourself. Suitable for simple rectangular windows in non-period properties.

Amazon and eBay

Generic DIY secondary glazing kits, acrylic sheets, magnetic tape, and plastic film kits are widely available on Amazon and eBay for £30-£120 per window. Quality varies, so check reviews carefully. These kits are often unbranded imports and may not include UK-specific installation guidance.

Frequently asked questions

How much does DIY secondary glazing cost?

DIY secondary glazing kits cost between £50 and £150 per window for materials, depending on window size and system type. Magnetic acrylic kits cost £80-£150 per window, basic adhesive-fix kits cost £40-£80, and plastic film kits cost £10-£30. Professional installation costs £200-£600 per window, making DIY around 70-85% cheaper.

Is DIY secondary glazing as effective as professional systems?

DIY secondary glazing can achieve similar thermal and acoustic performance to professional systems if installed correctly with a good seal. Thermal performance (U-value reduction of 30-50%) is comparable. However, DIY kits may not last as long (5-10 years vs. 20-30 years), may have less polished aesthetics, and typically cannot match the build quality of bespoke aluminium professional systems with toughened glass panels.

Can I install secondary glazing myself if I am not a skilled DIYer?

Yes. Basic magnetic and adhesive secondary glazing kits require minimal DIY skills and can be installed in 1-2 hours per window using common household tools (tape measure, drill, spirit level). The key skills are accurate measurement and drilling straight holes. More complex hinged or sliding systems require moderate DIY skills (cutting aluminium track, fitting hinges) and may take 3-4 hours per window.

What are the best DIY secondary glazing systems?

Magnetic acrylic systems offer the best balance of performance, ease of installation, and removability. Recommended options include Magnetite UK DIY kits (£120-£180 per window), Easyglaze magnetic systems (£80-£150), and Screwfix/Wickes polycarbonate kits (£50-£100) for budget applications. Plastic film kits (£10-£30) are cheaper but less durable and suitable only for temporary winter use.

Does DIY secondary glazing work on sash windows?

Yes. DIY magnetic or adhesive secondary glazing works well on sash windows when fitted to the window reveal (the recess around the window frame) rather than directly to the sashes. This allows the sashes to open and close behind the secondary pane. Use magnetic systems so you can remove the secondary pane when you need to open the window for ventilation or cleaning. For more detail, see our guide to secondary glazing for sash windows.

How long does DIY secondary glazing last?

Acrylic or polycarbonate DIY secondary glazing panels typically last 5-15 years before they become scratched, yellowed, or the seals degrade. Plastic film systems last one heating season (4-6 months). Magnetic strips and steel tracks can last 10-20 years if not damaged. Professional systems with aluminium frames and toughened glass last 20-30 years with minimal maintenance.

Will DIY secondary glazing damage my window frames?

No, if installed correctly. Magnetic and adhesive systems fix to the window frame or reveal using non-invasive methods (self-adhesive steel strip or small screws). Removing the system leaves minimal trace: screw holes can be filled, and adhesive residue can be cleaned with white spirit or isopropyl alcohol. Plastic film systems use double-sided tape that peels off cleanly. Always test adhesive in an inconspicuous area first, especially on painted or varnished period woodwork.