In skillion roofs, the roof space is generally inaccessible, the insulation thickness is restricted by the rafter depth and there should be a 25mm gap between the top of the insulation and the underside of the roof underlay.

Standard ceiling products which provide high R-values cannot be used in a skillion roof due to the thickness restriction and need to maintain the required clearances. If used, ventilation can be restricted and may result in compression of insulation effectively reducing the R-value performance and potentially creating problems due to the lack of ventilation.

Pink Batts has an exclusive range dedicated to insulating skillion roofs: Pink Batts Skillion Roof R3.2 with a maximum thickness of 115mm and Pink Batts Skillion Roof R3.6 with a maximum thickness of 165mm. The range is designed to be used in skillion roof construction while still achieving the minimum 25mm clearance between the roof underlay and the top of the insulation in:

• New buildings and retrofits of existing ceilings.
• Modern ‘lean-to’ style extensions on existing homes.
• Low profile roof design and restricted roof cavities
• Cathedral style roofs and raked ceilings are generally skillion roof constructions where the ceiling line and roof line are in parallel

Besides the skillion range, the wall range of Pink Batts glass wool insulation also makes for an excellent alternative where architects want to achieve higher R-values in the same thickness. The table below shows the maximum R-value that can be achieved in a skillion roof for a given thickness in the Pink Batts glass wool range: