Replacing windows in a standard UK semi-detached home now averages £12,000, according to Energy Saving Trust data. But that number is a baseline; your actual quote will swing by thousands depending on whether you choose uPVC, aluminium, or timber.

Quick Cost Comparison

MaterialGlazingEstimated Price (Per Window)Best For
uPVCDouble£600 – £1,200Budget & Thermal Efficiency
AluminiumDouble£1,200 – £2,200Modern Aesthetics & Strength
TimberDouble£1,800 – £3,500Heritage & Character

Regional Price Variance (Standard uPVC Double)

LocationPrice RangeVariance
London£600 – £1,200Baseline
Manchester£500 – £1,000-15% to -20%

Performance Upgrade: Double vs Triple Glazing

SpecificationPrice DeltaU-Value ImpactTypical Use Case
Double GlazingBase1.2 - 1.6Standard UK Retrofit
Triple Glazing+20% to 30%0.8 - 1.0Passivhaus / North-facing rooms

What most guides miss: The “Hidden” 20%

Most online cost calculators ignore the installation failure rate and the VAT trap. You’ll often see “supply only” prices that exclude the £150-£300 per-window installation fee. More critically, if you are retrofitting an older property, you’re likely to hit structural rot in the reveals—a discovery that can add 20% to your final bill mid-project.

If you’re tackling a full-home retrofit, don’t just look at windows. Combining window upgrades with high-performance insulation and PV solar can radically shift your EPC rating. Check our Passivhaus spec guide or see how this integrates with IWantSolar for total energy autonomy. For those dealing with properties that are effectively Unmortgageable due to outdated glazing and damp, a strategic retrofit is the only way to recover asset value.

Next Steps

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