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## Double thickness brick wall without air gap

 Wall Component Conductivity (W/mK) Thickness(m) Conductance(W/m2K) Resistance (m2K/W) Outside Air Layer 0.04 External render 0.50 0.018 27.78 0.04 External brick 0.77 0.102 7.55 0.13 Internal brick 0.56 0.102 5.49 0.18 Dense Plaster 0.57 0.013 43.85 0.02 Inside Air Layer - - - 0.13 Totals 0.19 0.54 Overall U-Value 1.85

#### Wall Component

Conductivity (W/mK)

Thickness(m)

Conductance

(W/m2K)

Resistance

(m2K/W)

Resistance

(m2K/W)

Outside Air Layer

0.04

Wooden Cladding and battens

0.13

0.05

2.6

-

0.38

Sheltered surface resistance

0.13

-

External brick

0.77

0.102

7.55

0.13

0.13

Internal brick

0.56

0.102

5.49

0.18

0.18

Dense Plaster

0.57

0.013

43.85

0.02

0.02

Inside Air Layer

-

-

-

0.13

0.13

Totals

0.19

0.59

0.88

Net Resistance

0.61

Net U Value (W/m2K)

1.64

Note: BRE guidance is to disregard the rain cladding and use a sheltered surface resistance value. However, the calculation should allow for timber battens. If the battens occupy 10% of the surface area then the effective resistance is
1/((0.9/0.59)+(0.1/0.88)) = 1/(1.64 + 0.11) = 0.61 m2K/W

#### Wall Component

Conductivity (W/mK)

Thickness(m)

Conductance

(W/m2K)

Resistance

m2K/W

Resistance

m2K/W

Outside Air Layer

0.04

0.04

Wooden Cladding and Battens

0.13

0.05

2.6

-

0.38

0.13

0.025

5.2

0.19

-

Insulation between battens

0.03

0.025

1.2

0.83

-

External brick

0.77

0.102

7.55

0.13

0.13

Internal brick

0.56

0.102

5.49

0.18

0.18

Dense Plaster

0.57

0.013

43.85

0.02

0.02

Inside Air Layer

-

-

-

0.13

0.13

Totals

0.19

1.52

0.88

Net Resistance

1.4

Net U Value (W/m2K)

0.71

#### Wall Component

Conductivity (W/mK)

Thickness(m)

Conductance

(W/m2K)

Resistance (m2K/W)

Outside Air Layer

-

-

-

0.04

External render

0.50

0.018

27.78

0.04

External brick

0.77

0.102

7.55

0.13

Air Cavity

-

0.1

-

0.18

Internal brick

0.56

0.102

5.49

0.18

Dense Plaster

0.57

0.013

43.85

0.02

Inside Air Layer

-

-

-

0.13

Totals

0.19

0.72

Overall U-Value

### 1.39

#### Wall Component

Conductivity (W/mK)

Thickness(m)

Conductance

(W/m2K)

Resistance (m2K/W)

Outside Air Layer

-

-

-

0.04

External render

0.50

0.018

27.78

0.04

External brick

0.77

0.102

7.55

0.13

Insulated Cavity

0.039

0.089

0.44

2.27

Internal brick

0.56

0.102

5.49

0.18

Dense Plaster

0.57

0.013

43.85

0.02

Inside Air Layer

-

-

-

0.13

Totals

0.19

2.81

Overall U-Value

0.36

#### Wall Component

Conductivity (W/mK)

Thickness(m)

Conductance

(W/m2K)

Resistance (m2K/W)

Outside Air Layer

-

-

-

0.04

External brick

0.77

0.102

7.55

0.13

Air Cavity

-

0.1

-

0.18

Internal brick

0.56

0.102

5.49

0.18

Dense Plaster

0.57

0.013

43.85

0.02

Inside Air Layer

-

-

-

0.13

Totals

0.19

0.68

Overall U-Value

### 1.47

#### Wall Component

Conductivity (W/mK)

Thickness(m)

Conductance

(W/m2K)

Resistance (m2K/W)

Outside Air Layer

- - -

0.04

External render

0.50

0.018

27.78

0.04

External brick

0.77

0.102

7.55

0.13

Insulated Cavity

0.039

0.1

0.39

2.56

Internal brick

0.56

0.102

5.49

0.18

Dense Plaster

0.57

0.013

43.85

0.02

Inside Air Layer

-

-

-

0.13

Totals

0.19

3.1

Overall U-Value

0.32