Secondary Glazing Results & Performance Questions

Question 1

How much noise does secondary glazing reduce?

Secondary Glazing Installers · Accepted Answer

Secondary glazing reduces noise by 30-50dB depending on glass type and installation. Standard secondary glazing achieves 30-35dB reduction, while acoustic-grade glass achieves 45-50dB. To put this in perspective: a busy road at 75dB becomes a quiet 25-30dB inside - similar to a library. Traffic noise becomes barely perceptible, and conversations outside are inaudible.

Question 2

Is secondary glazing effective for traffic noise?

Secondary Glazing Installers · Accepted Answer

Extremely effective. Traffic noise is predominantly low-frequency sound, which secondary glazing handles exceptionally well due to the air gap between panes. Our London installations typically reduce road noise from 'constant disturbance' to 'barely noticeable'. Clients report significantly better sleep quality and reduced stress. For busy A-roads, we recommend 100mm+ air gaps with acoustic laminated glass.

Question 3

What difference does acoustic glass make?

Secondary Glazing Installers · Accepted Answer

Acoustic glass provides an additional 10-15dB reduction over standard glass. Standard 4mm glass: 30-35dB reduction. 6.4mm acoustic laminated: 40-45dB reduction. 10.8mm acoustic laminated: 45-50dB reduction. The laminated interlayer specifically dampens sound vibrations. For properties on busy roads, under flight paths, or near railways, acoustic glass is highly recommended.

Question 4

How much does secondary glazing improve thermal efficiency?

Secondary Glazing Installers · Accepted Answer

Secondary glazing reduces heat loss through windows by 50-65%. A single-glazed window has a U-value of around 5.0 W/m²K. Adding secondary glazing improves this to 1.8-2.2 W/m²K - approaching double glazing performance (1.4-1.6 W/m²K). With low-E glass options, U-values of 1.5-1.7 W/m²K are achievable, matching standard double glazing.

Question 5

What U-value can secondary glazing achieve?

Secondary Glazing Installers · Accepted Answer

U-value measures heat loss - lower is better. Single glazing: 5.0 W/m²K (poor). Secondary glazing with 20mm gap: 2.8 W/m²K (good). Secondary glazing with 100mm gap: 1.9 W/m²K (very good). Secondary glazing with low-E glass: 1.5-1.7 W/m²K (excellent). Standard double glazing: 1.4-1.6 W/m²K. Secondary glazing can match or approach double glazing thermal performance.

Question 6

Why is the air gap important for performance?

Secondary Glazing Installers · Accepted Answer

The air gap between your existing window and secondary glazing is crucial for both thermal and acoustic performance. Thermal: optimal gap is 20-100mm - too small and convection currents reduce insulation. Acoustic: larger gaps (100-200mm) provide better low-frequency noise reduction. We typically recommend 100mm gaps where possible, balancing both benefits and practical considerations.

Question 7

Will secondary glazing stop condensation?

Secondary Glazing Installers · Accepted Answer

Secondary glazing significantly reduces condensation by keeping the inner glass surface warmer. The secondary panel acts as a barrier, preventing warm moist air from reaching the cold original glass. Most clients see 80-90% reduction in window condensation. Some condensation may occur between panes if humidity is very high - this is why we include discrete ventilation in our systems.

Question 8

What if condensation forms between the panes?

Secondary Glazing Installers · Accepted Answer

Slight condensation between panes can occur in high-humidity environments. Our secondary glazing includes discrete trickle vents that allow moisture to escape while maintaining acoustic and thermal performance. If you experience persistent condensation, it usually indicates high indoor humidity - we recommend adequate ventilation and possibly a dehumidifier. Our systems are designed to minimize this issue.

Question 9

How much will I save on energy bills?

Secondary Glazing Installers · Accepted Answer

Secondary glazing typically reduces heating bills by 10-15%, equating to £150-£400 annual savings depending on property size and existing glazing. A Victorian terrace with single glazing might save £350+/year. A 1970s house with older double glazing might save £150-£200/year. Combined with reduced heating demand, many customers also benefit from being able to use a smaller boiler setting.

Question 10

How quickly will secondary glazing pay for itself?

Secondary Glazing Installers · Accepted Answer

Based on energy savings alone: 8-15 years. Including increased property value: 4-8 years. Including quality of life improvements (better sleep, reduced stress): immediate return. A £4,000 installation saving £300/year in energy repays in 13 years. Add £10,000 property value increase and ROI becomes positive within 5 years. Most clients report the comfort benefits are worth the investment regardless of financial return.

Question 11

Does secondary glazing increase property value?

Secondary Glazing Installers · Accepted Answer

Yes. Secondary glazing improves EPC ratings (typically by 1-2 bands), which directly impacts property value. Research suggests each EPC band improvement adds 2-5% to property value. A property improved from E to C could see £8,000-£20,000 added value on a £400,000 home. Additionally, quiet, energy-efficient properties command premium prices, especially in London.

Question 12

How much will secondary glazing improve my EPC rating?

Secondary Glazing Installers · Accepted Answer

Secondary glazing typically improves EPC ratings by 1-2 bands. A property rated E might improve to D or C. The exact improvement depends on other factors (insulation, heating system, etc.), but window improvements are weighted heavily in EPC calculations. For rental properties, this can be crucial for meeting MEES requirements (minimum E rating, moving to C by 2028).

Question 13

Is secondary glazing as good as replacing windows?

Secondary Glazing Installers · Accepted Answer

For thermal performance: secondary glazing achieves 80-95% of double glazing effectiveness. For acoustic performance: secondary glazing is often BETTER than double glazing due to the larger air gap. For heritage properties: secondary glazing preserves original windows. For cost: secondary glazing is 50-70% cheaper. For disruption: minimal compared to full replacement. The 'best' option depends on your priorities.

Question 14

How long does secondary glazing last?

Secondary Glazing Installers · Accepted Answer

Quality secondary glazing lasts 25-30+ years with minimal maintenance. The aluminium frames are corrosion-resistant and maintain their finish. Glass is obviously permanent unless damaged. Moving parts (hinges, slides) may need adjustment or replacement after 15-20 years. Our 10-year warranty covers all components, with many installations from 20+ years ago still performing perfectly.

Performance & Results Questions

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Performance & Results Questions

1How much noise does secondary glazing reduce?Noise

2Is secondary glazing effective for traffic noise?Noise

3What difference does acoustic glass make?Noise

4How much does secondary glazing improve thermal efficiency?Thermal

5What U-value can secondary glazing achieve?Thermal

6Why is the air gap important for performance?Technical

7Will secondary glazing stop condensation?Condensation

8What if condensation forms between the panes?Condensation

9How much will I save on energy bills?Savings

10How quickly will secondary glazing pay for itself?Value

11Does secondary glazing increase property value?Value

12How much will secondary glazing improve my EPC rating?EPC

13Is secondary glazing as good as replacing windows?Comparison

14How long does secondary glazing last?Longevity

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Installation Questions

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Acoustic Questions

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