J3D7 sets varying minimum ceiling insulation R-Values depending on the roof construction, colour and ventilation levels, and the buildings location across different NCC climate zones. J3D7 also states that reflective insulation should have a surface emittance of not more than 0.05 and must be adjacent to a roof space of at least 20 mm. Additionally, in climate zones 3 to 8, the reflective insulation must be downward-facing to ensure it is effective.

There are multiple options to mitigate thermal bridging in metal-framed roofs, These provisions all aim to reduce the overall heat transfer through the metal framing so that it is approximately the same as an equivalent timber-framed structure. For pitched roofs with horizontal ceilings, options include achieving a specified Total R-Value or increasing the insulation R-Value between the ceiling frames, or adding a continuous insulation layer above or below the ceiling framing, or achieving the required ceiling insulation by stacking layers such that the top layer is oriented to cover the ceiling joist or bottom chord of the truss. For flat, skillion, or cathedral roofs, provisions are provided to either achieve specified Total R-Values in Table J3D7t or take mitigating actions specified in Table J3D7u. Thermal bridging provisions apply in addition to the thermal break provisions.

For ventilated roof spaces in climate zones 6, 7, and 8, continuous insulation placed above the primary insulation layer to mitigate thermal bridging must have a vapour permeance at least that of the primary insulation layer to avoid the build-up of condensation.

J3D7 also allows for compensation in instances where operational or safety concerns necessitate reduced ceiling insulation. Specifically, the loss of insulation must be offset as laid out in Table J3D7w. The provision also allows for reduced ceiling insulation R-Values near external walls, provided that thicker insulation is used elsewhere to compensate. This is in recognition of the fact that the roof space height typically reduces at the perimeter, where the roof meets the walls. 

Roofs constructed with insulated sandwich panels are not subject to these rules but must meet the minimum Total R-Value requirements stipulated in Table J3D7x.

Maximum solar absorptance requirements are also set to discourage the use of dark-coloured roofs in hot climates.