Insulation for Pitched Metal Roof with Flat Ceiling from Fletcher

Total R5.3 Winter / Total R5.4 Summer

Sisalation® facing foil over roof battens attributes nearly R0.6 in winter (heat flow down) and R1.1 in summer (heat flow up) for the unventilated attic air-space under the reflective foil. Combined with 55mm R1.3 Fletcher Insulation Building Blanket between the foil and pitched metal deck roof, allowing for blanket recovery to its nominal thickness between battens, and R3.0 Insulco® Fat Batts or R3.0 Pink Batts® between joists on a flat plasterboard ceiling, the thermal performance calculation for the roof system is a Total R5.3 for winter conditions (heat flow up) and Total R5.4 for summer conditions (heat flow down). This roof system complies with the minimum BCA 2010 Energy Efficiency requirements for residential buildings in Australian Climate Zones 1-7 and commercial buildings in all climate zones.

Sisalation facing options include Light Duty (436), Medium Duty (430), and Heavy Duty (450). The 'Duty' classifications refer to the difference in strength and tearability. All provide the same reflective air space R-value.

For superior thermal and acoustic performance, a 75mm thick Fletcher Insulation Building Blanket with a material R1.8 value could be used under the metal deck roof. The best method for any improving thermal performance is by increasing the R-value of the ceiling batts.