Secondary Glazing vs Double Glazing: Complete Comparison
Make an informed decision with our comprehensive comparison of secondary glazing and double glazing options, covering costs, performance, installation, and suitability for different property types.
The choice between secondary and double glazing depends on your property type, budget, and whether you're in a listed building or conservation area.
Quick Comparison Overview
| Feature | Secondary Glazing | Double Glazing |
|---|---|---|
| Average Cost | £300-600/window see full price guide | £600-1,200/window |
| Installation | DIY options or professional | Professional only |
| Installation Time | Same day possible | 2-3 days minimum |
| Planning Permission | Not required | Often required |
| Heritage Properties | Ideal solution | Often prohibited |
| Noise Reduction | Up to 80% | Up to 60% |
| Thermal Efficiency | 60% improvement | 70% improvement |
| Disruption Level | Minimal | Significant |
Detailed Feature Comparison
Cost Analysis
Secondary Glazing
- • Material costs: £150-300 per m²
- • Installation: £50-100 per m²
- • Total average: £200-400 per m²
- • Payback period: 3-5 years
Double Glazing
- • Material costs: £300-600 per m²
- • Installation: £100-200 per m²
- • Total average: £400-800 per m²
- • Payback period: 8-12 years
Installation Process
Secondary Glazing
- • Duration: Same day installation possible
- • Disruption: Minimal, work from inside
- • Preparation: No structural changes needed
- • Mess: Very little dust or debris
Double Glazing
- • Duration: 2-3 days minimum per property
- • Disruption: Significant, external access needed
- • Preparation: Frame removal and replacement
- • Mess: Considerable dust and debris
Thermal Performance
Secondary Glazing
- • U-Value improvement: 2.8 to 1.8 W/m²K
- • Heat loss reduction: 40-60%
- • Air gap: 100-200mm (excellent insulation)
- • Condensation: 90% reduction
Double Glazing
- • U-Value: 1.4-2.0 W/m²K
- • Heat loss reduction: 50-70%
- • Air gap: 16-20mm (good insulation)
- • Condensation: 95% reduction
Noise Reduction
Secondary Glazing
- • Noise reduction: Up to 80% (15-25 dB)
- • Air gap advantage: Large cavity breaks sound waves
- • Glass options: Acoustic laminated available
- • Best for: Traffic, aircraft, construction noise
Double Glazing
- • Noise reduction: Up to 60% (10-15 dB)
- • Air gap limitation: Small cavity less effective
- • Glass options: Acoustic glass available
- • Best for: General noise reduction
Performance Comparison
Noise Reduction
Secondary glazing typically outperforms double glazing due to its larger air gap. Acoustic glazing can achieve up to 45dB noise reduction.
Thermal Efficiency
Similar performance: both achieve 60%+ thermal improvement. Secondary glazing's larger air gap provides excellent insulation.
When to Choose Each Option
Choose Secondary Glazing When:
- You're in a listed building where replacement windows aren't allowed
- You have original sash windows or bay windows worth preserving
- You need maximum noise reduction (secondary glazing creates a larger air gap)
- You want to prevent condensation without replacing windows
- You want minimal disruption during installation
- Budget is a key consideration
- Original windows are in good condition
- You're a tenant with landlord restrictions
Choose Double Glazing When:
- Original windows need complete replacement (no planning restrictions)
- You're renovating a modern property
- Maximum thermal efficiency is required
- You're undertaking major renovations
- No planning restrictions exist
- Long-term investment is the priority
- Modern aesthetic is desired
- Building regulations compliance is needed
London Period Properties
For most View All London Areas, secondary glazing is the only legal option. Conservation areas and listed building regulations often prohibit window replacements, making secondary glazing the ideal solution.
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