- Example U Value Calculation -
Typical Blockwork with Cavity
 
 
Construction Type
Element: Wall - Blockwork
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
-
-
Blockwork, light
100.00
0.200
0.500
30.00
3.00
Cavity (uninsulated)
-
-
0.180
-
-
Blockwork, dense
100.00
1.667
0.060
100.00
10.00
Dot & dab cavity
-
0.100
-
-
Plasterboard & skim
15.00
0.167
0.090
45.00
0.68
Inside surface resistance
-
-
0.130
U-Value, Proportionate Area Method:
0.957 (W/m²K)


50mm 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
50.00
0.028
1.786
0.00
0.00
Blockwork, light
100.00
0.200
0.500
30.00
3.00
Cavity (uninsulated)
-
-
0.180
-
-
Blockwork, dense
100.00
1.667
0.060
100.00
10.00
Dot & dab cavity
-
0.100
-
-
Plasterboard & skim
15.00
0.167
0.090
45.00
0.68
Inside surface resistance
-
-
0.130
U-Value, Proportionate Area Method:
0.340 (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
400.00
0.00
Blockwork, light
100.00
0.200
0.500
30.00
3.00
Cavity (uninsulated)
-
-
0.180
-
-
Blockwork, dense
100.00
1.667
0.060
100.00
10.00
Dot & dab cavity
-
0.100
-
-
Plasterboard & skim
15.00
0.167
0.090
45.00
0.68
Inside surface resistance
-
-
0.130
U-Value, Proportionate Area Method:
0.282 (W/m²K)



 

Line Break

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.