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Comparing DIY secondary glazing kits with professional installation. When to save money doing it yourself, and when to call in the experts.
Search online for "secondary glazing" and you'll find two very different worlds: professional installation companies quoting thousands of pounds, and DIY kits available for a few hundred. The price difference is dramatic—but is the performance difference equally significant?
Let's break down exactly what you get with each approach, so you can make an informed decision for your property.
Cost: £30-£80 per window
What you get: Acrylic or polycarbonate sheets with magnetic strips that attach to steel tape stuck around your window frame.
Pros:
Cons:
Cost: £5-£15 per window
What you get: Plastic film stretched over double-sided tape and shrunk with a hairdryer.
Pros:
Cons:
Cost: £100-£250 per window
What you get: Aluminium or plastic frames with glass or acrylic, screwed or clipped into your reveal.
Pros:
Cons:
Cost: £300-£800 per window (depending on size, glass type, and specification)
What you get: Bespoke frames manufactured to exact measurements, professional installation with proper sealing, choice of glass types, and opening mechanisms matched to your original windows.
1. Made-to-Measure Fit
Professional secondary glazing is manufactured to the millimetre based on precise site measurements. Old buildings are never perfectly square—professional installers accommodate this with bespoke frames and adjustable seals. D
For expert secondary glazing advice and free consultations for listed buildings in London, contact Secondary Glazing Specialist on 020 7060 1572.
Dr Sarah Chen
Building Physics Consultant
Search online for "secondary glazing" and you'll find two very different worlds: professional installation companies quoting thousands of pounds, and DIY kits available for a few hundred. The price difference is dramatic—but is the performance difference equally significant?
Let's break down exactly what you get with each approach, so you can make an informed decision for your property.
Cost: £30-£80 per window
What you get: Acrylic or polycarbonate sheets with magnetic strips that attach to steel tape stuck around your window frame.
Pros:
Cons:
Cost: £5-£15 per window
What you get: Plastic film stretched over double-sided tape and shrunk with a hairdryer.
Pros:
Cons:
Cost: £100-£250 per window
What you get: Aluminium or plastic frames with glass or acrylic, screwed or clipped into your reveal.
Pros:
Cons:
Cost: £300-£800 per window (depending on size, glass type, and specification)
What you get: Bespoke frames manufactured to exact measurements, professional installation with proper sealing, choice of glass types, and opening mechanisms matched to your original windows.
1. Made-to-Measure Fit
Professional secondary glazing is manufactured to the millimetre based on precise site measurements. Old buildings are never perfectly square—professional installers accommodate this with bespoke frames and adjustable seals. DIY kits use standard sizes and ask you to "make do."
2. Proper Sealing
The acoustic and thermal performance of secondary glazing depends almost entirely on creating an airtight seal. Professional installation uses compression seals, brush seals, and proper gaskets. The frame-to-reveal junction is sealed with appropriate materials. DIY installations rarely achieve this level of airtightness.
3. Glass Specification
Professional installations offer choices:
DIY kits typically offer only standard glass or acrylic with no acoustic properties.
4. Opening Mechanisms
Professional units can be specified with:
This means you retain full use of your windows for ventilation and cleaning.
5. Aesthetic Quality
Heritage-grade professional secondary glazing uses slim aluminium profiles (20-25mm) that can be powder-coated to any RAL colour. Meeting rails align with original window divisions. The result is discrete—often invisible to casual observation.
DIY solutions invariably look like what they are: an afterthought.
| Measure | DIY Magnetic/Film | DIY Fixed Panel | Professional Installation |
|---|---|---|---|
| Noise reduction | 10-18dB | 18-25dB | 35-54dB |
| Draught elimination | Partial | Moderate | Complete |
| Heat loss reduction | 15-25% | 30-45% | 50-65% |
| Lifespan | 1-3 years | 5-10 years | 25+ years |
| Suitable for listed buildings | No | No | Yes |
DIY secondary glazing can be appropriate when:
Invest in professional secondary glazing when:
Consider this: if DIY secondary glazing costs £150 per window but achieves only half the noise reduction and thermal improvement of professional installation, is it really cheaper?
You'll spend the money, spend your time installing it, and still hear the traffic. In three years, the acrylic will be scratched and yellowed, and you'll either live with it or replace it—possibly with the professional installation you should have chosen initially.
For most London homeowners with period properties, professional secondary glazing represents better value despite the higher upfront cost.
If you're considering secondary glazing for a London property—especially a period home in Kensington, Chelsea, Islington, or any conservation area—we'd recommend getting a professional survey before deciding.
A good specialist will assess your specific situation, explain your options honestly, and provide a detailed quotation. If DIY would genuinely work for your circumstances, an ethical company will tell you.
Request your free survey or call 020 7060 1572 to discuss your project.
London's leading secondary glazing specialists for Grade I, Grade II, and Conservation Area properties. Every project begins with a complimentary heritage survey.
