Ceiling Insulation Area Local Practice Interpretation

Published: 06 October 2009 / Amendment 6 / BCA 2011

How is DTS Compliance Interpreted?

BCA Part 3.2.1.2 Roof – sub-clause (a) prescribes that a roof must achieve the Total R-Value specified in Figure 3.12.1.1. Figure 3.12.1.1 describes the minimum R-Value of added insulation required for typical roof and ceiling configurations.

3.12.1.2 Roof – sub-clause (c) requires the minimum added R-Value to be adjusted for the reduction in the insulated ceiling area caused by penetrations at exhaust fans, flues or recessed lights. Table 3.12.1.1a specifies the adjusted R-Value of ceiling insulation required for any nominated penetration area percentage.

3.12.1.1 sub-clause (a) requires insulation in ceilings, walls and floor to form a continuous barrier and 3.12.1.1 sub-clause (c) requires insulation to lap over uninsulated walls (local practice masonry construction).

What is the Ceiling Insulation Area?

BCA Part 3.12.1.2 Roof does not require per storey calculation and 3.12.1.5 Floors – sub-clause (a) excludes the intermediate floor in a building with more than one storey. Therefore the ceiling insulation area is the total area within the enclosing walls of the building.

For single storey buildings this is straight forward (same area as for External Glazing).

For buildings of more than one storey this area is the total of all the individual ceiling areas within the enclosing walls of all storeys.

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