Achieving higher thermal performance in skillion roofs

Achieving higher thermal performance in skillion roofs

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

Therefore, 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® provides the solution with an exclusive range dedicated to insulating skillion roofs - Pink® Batts® Skillion Roof R3.2 with maximum thickness of 115mm and Pink® Batts® Skillion Roof R3.6 with maximum thickness of 165mm.

The range is designed to be used in skillion roof constructions 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 you 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 Pink® Batts® glass wool range:

Insulation Thickness (mm)

Rafter depth (mm)

Product or product combination



Pink® Batts® Ultra® R4.0 wall 



Pink Batts Skillion Roof R3.6



Pink® Batts® Skillion Roof R3.2

Click here for more information, plus installation and spec sheets.