R0900 Flat Metal Roof with no Ceiling (warehouse)

Structure

Flat metal roof at 0 to 5o pitch, with Rm2.5 foil faced blanket laid over safety mesh with a spacer installed directly under metal sheeting.

Installation

• Foil faced blanket insulation laid over safety mesh. Laps in foil should be 150mm, any tears or holes in the reflective foil should be repaired with foil tape. Where foil faced blanket is used, it should be allowed to recover to its nominal thickness by dishing the safety mesh or by providing a suitable spacer. Foil side of blanket should face into the air space below.
• Foil sarking only insulation laid over safety mesh. Laps in foil should be 150mm. Any tears or holes in the reflective foil should be repaired with foil tape. Bright side of foil to face into the air space downward.
• Tight safety mesh denotes no air space between reflective insulation and flat metal roof. Hence no contribution from an air space. Alternatively a spacer must be provided as per air space dimensions nominated. 

NOTE: Total R-Values can be increased by substituting bulk insulation products of higher Material R-Value.

A. Calculations assumptions in accordance with AS/NZS 4859.1:2002.  Amendment 1. 2006. Amendment 1. 2006 on the path of the insulation, as required by the BCA Vol 1. Part J and Vol 2. Section 3.12.

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.