Approved Document L (conservation of fuel and power)
What it covers
What it means for our calculators
Where to read it
Calculators that use it
Insulation thickness calculator
Example: Insulation: at least 100.4 mm
U-value calculator
Example: U-value: 0.181 W/m²K
Loft insulation calculator
Example: Order: 5 rolls for layer 1 and 8 rolls for layer 2 (270 mm total)