- Example U Value Calculation -
Typical Wates Properties - Main Wall Areas
 
 
Construction Type
Element: Wall - Concrete Panel
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
-
-
Concrete
32.00
1.667
0.019
200.00
6.40
Cavity fill
100.00
0.040
2.500
10.00
1.00
Stramit board
25.00
0.081
0.309
75.00
1.88
Plaster, average 10mm
10.00
0.500
0.020
60.00
0.60
Inside surface resistance
-
-
0.130
U-Value, Proportionate Area Method:
0.330 (W/m²K)


40mm Expanded Polystyrene
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 EPS Insulation
40.00
0.036
1.111
0.00
0.00
Concrete
32.00
1.667
0.019
200.00
6.40
Cavity fill
100.00
0.040
2.500
10.00
1.00
Stramit board
25.00
0.081
0.309
75.00
1.88
Plaster, average 10mm
10.00
0.500
0.020
60.00
0.60
Inside surface resistance
-
-
0.130
U-Value, Proportionate Area Method:
0.237 (W/m²K)


30mm PIR
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 PIR Insulation
30.00
0.028
1.071
240.00
7.20
Concrete
32.00
1.667
0.019
200.00
6.40
Cavity fill
100.00
0.040
2.500
10.00
1.00
Stramit board
25.00
0.081
0.309
75.00
1.88
Plaster, average 10mm
10.00
0.500
0.020
60.00
0.60
Inside surface resistance
-
-
0.130
U-Value, Proportionate Area Method:
0.239 (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.