- Example U Value Calculation -
Typical Brickwork with Cavity
 
 
Construction Type
Element: Wall - Brickwork
Exposure: Normal
Internal Surface Emissivity: High
External Surface Emissivity: High
Building Use: Domestic House / Flat


Prior to WBS system application
Thickness
Thermal Conductivity
Thermal Resistance
Vapour Resistivity
Vapour Resistance
 
(mm)
(W/m²K)
(m²K/W)
(MNs/gm)
(MNs/g)
Outside surface resistance
-
-
0.040
-
-
Traditional Render
20.00
0.556
0.036
100.00
2.00
Brickskin, external
102.50
0.752
0.136
50.00
5.13
Cavity
-
-
0.180
-
-
Brickskin, internal
102.50
0.541
0.189
60.00
6.15
Plaster, dense
13.00
0.500
0.026
60.00
0.78
Inside surface resistance
-
-
0.130
U-Value, Proportionate Area Method:
1.382 (W/m²K)


80mm Mineral Wool
Thickness
Thermal Conductivity
Thermal Resistance
Vapour Resistivity
Vapour Resistance
 
(mm)
(W/m²K)
(m²K/W)
(MNs/gm)
(MNs/g)
Outside surface resistance
-
-
0.040
-
-
WBS Polymer Cement Render
10.00
0.115
0.087
0.00
0.00
WBS Mineral Wool Insulation
80.00
0.036
2.222
0.00
0.00
Traditional Render
20.00
0.556
0.036
100.00
2.00
Brickskin, external
102.50
0.752
0.136
50.00
5.13
Cavity
-
-
0.180
-
-
Brickskin, internal
102.50
0.541
0.189
60.00
6.15
Plaster, dense
13.00
0.500
0.026
60.00
0.78
Inside surface resistance
-
-
0.130
U-Value, Proportionate Area Method:
0.330 (W/m²K)


50mm Phenolic
Thickness
Thermal Conductivity
Thermal Resistance
Vapour Resistivity
Vapour Resistance
 
(mm)
(W/m²K)
(m²K/W)
(MNs/gm)
(MNs/g)
Outside surface resistance
-
-
0.040
-
-
WBS Polymer Cement Render
10.00
0.115
0.087
0.00
0.00
WBS Phenolic Insulation
50.00
0.021
2.381
300.00
15.00
Traditional Render
20.00
0.556
0.036
100.00
2.00
Brickskin, external
102.50
0.752
0.136
50.00
5.13
Cavity
-
-
0.180
-
-
Brickskin, internal
102.50
0.541
0.189
60.00
6.15
Plaster, dense
13.00
0.500
0.026
60.00
0.78
Inside surface resistance
-
-
0.130
U-Value, Proportionate Area Method:
0.313 (W/m²K)



 

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Provided strictly for guidance purposes only. WBS accept no liability for errors or omissions.
For a full U-value calculation, including Condensation Risk Analysis and Temperature Profiles,
please contact WBS Technical Support on 08458 382380.