Building Construction Handbook, Eighth Edition

Notes:

1. For purposes of calculating U-values, the effect of mortar in

external brickwork is usually ignored as the density and

thermal properties of bricks and mortar are similar.

2. Where butterfly wall ties are used at normal spacing in an
   insulated cavity <†75 mm, no adjustment is required to
   calculations. If vertical twist ties are used in insulated
   cavities >75 mm, 0020 W/m^2 K should be added to the
   U-value.


3. Thermal conductivity () is a measure of the rate that heat is
   conducted through a material under specific conditions (W/mK).

Typical values †

Material Density
(kg/m^3 )

Conductivity ()

(W/mK)

FLOORS:

Cast concrete 2000 1 „33

Hardwood block/strip 700 0„1 8

Plywood/particle board 650 0„1 4

Screed 1 200 0„41

Softwood board 500 0„1 3

Steel tray 7800 50„00

INSULATION:

Expanded polystyrene board 20 0„035

Mineral wool batt/slab 25 0„038

Mineral wool quilt 1 2 0„042

Phenolic foam board 30 0„025

Polyurethane board 30 0„025

Urea formaldehyde foam 1 0 0„040

GROUND:

Clay/silt 1 250 1 „50

Sand/gravel 1 500 2„00

Homogenous rock 3000 3„50

Thermal Insulation, Density and Thermal Conductivity---2