Flat Metal Roof with Suspended Ceiling
ICANZ System Reference R1000
Structure
Flat metal roof at 0 to 12o pitch with foil faced blanket draped over purlins laying on safety mesh. Purlins may be at various centres. A suspended ceiling dropped 600mm below the roof has 10mm plasterboard fixed to the facing channels.
Insulation Installation
Reflective Foil insulation laid over safety mesh with the bright side facing downwards.
Safety mesh should be dished accordingly to provide airspace to achieve additional R-value component above the foil. Laps in foil should be 150mm, any tears or holes should be repaired with foil tape. Where blanket/foil is used the blanket is compressed over purlins, blanket should be allowed to fully recover to design thickness by dishing the safety mesh to accommodate the required thickness. Foil side of blanket should face into the airspace below.
Tight safety mesh denotes no airspace between reflective insulation and flat metal roof. Hence no contribution from an airspace.
NOTE: Total R-Values can be increased by substituting bulk insulation products of higher Material R-Value.
B. Temperatures and parameters are based on Australian climate assumptions. Air temperature difference 12oC (36oC less 24oC) for summer conditions and 6oC difference (18oC less 12oC) for winter.
C. Thermal resistance of air films and attic spaces based on values obtained from Section K5 and K6 of AS 4859.1:2006.
D. Building material elements based on 2000 AIRAH Handbook and attic thermal value based on AS4859.1 app K6 table K2.
E. Where reflective insulation is installed, a simple addition of R-values is not possible. Care must be taken to ensure the performance of reflective air spaces is not “double-counted”.
F. The emittance of the reflective surfaces are dependent on tested values and the conditions of the installation, as specified by AS/NZS 4859.1. Amendment 1. 2006