CBA U-Value Calculator

Welcome to the CBA U-value calculator. This simple tool will enable you to calculate the potential U-value for a cavity masonry wall based on a number of parameters. It includes an option to select a ‘Basic Wall’ which is based upon a brick, fully filled 100mm cavity and 100mm inner leaf block construction. This simplified U-value calculator uses BS EN ISO 6946 procedures and the latest version of the U-value conventions but incorporates generic material values. We recommend that you check any U-values using product specific values before using them as part of a calculation for obtaining building control approval.

Should you require any further assistance please contact our Technical Helpline on 0116 222 1507

• external render? no render sand/cement render polymer render
• thickness
• mm
• conductivity
• W/m·K

• external insulation? no external insulation EPS external insulation
• thickness
• mm
• conductivity
• W/m·K

• details about outer leaf? brick outer leaf high density outer leaf (1.21 W/m·K) medium density outer leaf (0.61 W/m·K) medium density outer leaf (0.49 W/m·K) low density outer leaf (0.33 W/m·K)
• thickness
• mm
• conductivity
• W/m·K

• details about cavity? cavity fully filled with mineral wool 0.042 W/m·K cavity fully filled with mineral wool 0.032 W/m·K cavity fully filled with foil-faced insul. cavity partially filled with mineral wool 0.042 W/m·K cavity partially filled with mineral wool 0.032 W/m·K cavity partially filled with foil-faced insulation (r=0.44) cavity partially filled with foil-faced insulation (r=0.64) cavity clear cavity with reflective membrane(r=0.44) cavity with reflective membrane(r=0.64)
• residual cavity
• mm
• cavity resistance
• m²K/W

• insul. thickness
• mm
• insul. conductivity
• W/m·K

• details about inner leaf? brick inner leaf high density block inner leaf (1.13 W/m·K) medium density block inner leaf (0.57 W/m·K) medium density block inner leaf (0.46 W/m·K) low density block inner leaf (0.30 W/m·K)
• thickness
• mm
• conductivity
• W/m·K

• internal insulation? no internal insulation internal insulation (0.036 W/m·K) internal insulation (0.032 W/m·K) internal insulation (0.023 W/m·K)
• thickness
• mm
• conductivity
• W/m·K

• details about internal finish? dense plaster light plaster plasterboard on dabs plasterboard on battens
• thickness
• mm
• conductivity
• W/m·K

• Thickness of wall is

• mm

• U-value of wall is

• W/m²K