EXTERNAL WALL INSULATION SYSTEMS / MINERAL FIBRE /
THERMAL PERFORMANCE
The thermal insulation requirements of the Building Regulations Parts L1 and L2 call for levels of thermal resistance for walls that can easily be achieved through the use of external wall insulation.
PermaRock Mineral Fibre Insulation has a lambda value of 0.035 W/mK (BS EN 12667 and BS EN 12939) or 0.033 W/mK (BS 874) and boards are available in a range of thicknesses from 30 mm.
Thermal calculations are carried out for each project to determine the optimum thickness of insulation required to achieve the required U-value.
The table shows how current and future U-value requirements for walls can be achieved using the PermaRock Mineral Fibre System.
| PERMAROCK MINERAL FIBRE INSULATION BOARD THICKNESS (mm) REQUIRED TO ACHIEVE THE TARGET U-VALUE SHOWN* |
|  |  |  |  |  |  |
| U-VALUE (W/m2L) | solid 229 mm brick | 102 mm brick
50 mm cavity
100 mm block | 200 mm no-fines | 150 mm lightweight metal frame 10 mm Pyrok | 89 mm timber stud frame 12 mm plywood | 140 mm aerated concrete block (7 N/mm2) |
|
| 0.35 | 80 | 75 | 80 | 80 | 75 | 65 |
| 0.32 | 90 | 85 | 90 | 90 | 85 | 75 |
| 0.30 | 100 | 90 | 100 | 100 | 90 | 80 |
| 0.27 | 110 | 100 | 110 | 110 | 110 | 90 |
| 0.25 | 120 | 110 | 120 | 120 | 115 | 100 |
| 0.20 | 150 | 150 | 150 | 150 | 145 | 140 |
| 0.15 | 210 | 200 | 200 | 200 | 200 | 190 |
* Based on PermaRock Mineral Fibre System incorporating PermaRock Mineral Fibre Insulation Boards with thermal conductivity of 0.033 W/mK (BS 874) and with plasterboard internally and PermaRock K-finish Acrylic Textured Render decorative finish, taking into account the effects of thermal bridging in accordance with BS EN ISO 6946:1997. The U-values are indicative only.
For complete U-value and condensation risk analyses for specific wall constructions please contact PermaRock's Technical Department.