Building Construction Handbook, Eighth Edition

Typical examples of contemporary construction practice that
achieve a thermal transmittance or U-value below 0„30 W/m^2 K~

120 mm mineral

wool cavity batts 100 mm lightweight

concrete block inner

leaf

13 mm lightweight

plaster

102.5 mm external

brick outer leaf

75 mm mineral

wool cavity batts lightweight concrete

blocks, density

460 kg/m^3

9.5 mm plasterboard

on dabs

T

102.5 mm external

brick outer leaf

50 mm wide cavity

40 mm mineral wool

cavity batts

mineral wool batts

T

VCL and 12.5 mm

plasterboard

breather membrane

and sheathing

board

102.5 mm external

brick outer leaf

TIMBER FRAME PART CAVITY FILL, T = 100 mm U = 0.26 W/m^2 K

T = 120 mm U = 0.24 W/m^2 K

T = 140 mm U = 0 .21 W/m^2 K

FULL FILL CAVITY WALL, Block density 750 kg/m^3 U = 0.25 W/m^2 K

Block density 600 kg/m^3 U = 0.24 W/m^2 K

Block density 475 kg/m^3 U = 0.23 W/m^2 K

FULL FILL CAVITY WALL,

T = 150 mm U = 0.26 W/m^2 K

T = 200 mm U = 0.24 W/m^2 K

T = 125 mm U = 0.28 W/m^2 K

Note: Mineral wool insulating batts have a typical thermal
conductivity () value of 0„038 W/mK.

Thermal Insulation -- External Walls