The vertical screw guides that support the batten are sharp enough to slice through the
building blanket. This means there is no fully compressed wool at the join.


Section J 1.2 (c) (i) of the Building Code of Australia 2009, Volume One

With the safety mesh pulled tight, the Roof Razor allows insulation to recover to its full nominal thickness between the purlins.  The screw guides part the wool and connect directly to the purlin, this is the only Australian system that can do this.  This means that there is no squashed insulation at the join, and no risk of the Roof Razor coming loose over time with vibration and thermal expansion/contraction.

Key advantages of the Roof Razor system

  • Wide enough to walk on (68mm)
  • Compatible with all concealed and pierced fix roofing profiles
  • 1200mm long to suit the building blanket
  • Pre-loaded fixings
  • Direct contact to the roof structure without thermal bridging
  • Minimal compression over the purlin

Which Roof Razor to use:

Insulation Thickness Non-Cyclonic Cyclonic
100mm 85mm 85mm C3
110mm 85mm 85mm C3
120mm 85 or 115mm 85 or 115mm C3
130mm 115mm 115mm C3
140mm 115mm 115mm C3
145mm 115mm 115mm C3


The Roof Razor bracket system is interconnecting by way of a 25mm recessed lap on one end. This lap ensures no screw fixing from the roof sheeting will sit atop a butt-join in the channel. The lap also acts as a guide for fixing consecutive brackets.

When fastening the Roof Razor the vertical supports of the bracket will slice through the building blanket, giving a direct connection between the vertical supports and the purlin. With downward pressure and a back and forwards motion the installer can sink the bracket into the wool prior to fixing the fasteners, if needed.

For wind regions A & B, 3 vertical supports and 6x12g fixings will suffice. For wind regions C 6x14g fixings and a Roof Razor cyclone washer must be used. Roof Razors are supplied pre-assembled with the screws pre-loaded.

Once the Roof Razor is secured to the purlin install the roof sheeting as per the manufacturer's instructions. The Roof Razor will suit any pierced fix or concealed fixed roofing system.

No Spacer or dishing
Timber Block Spacer
Roof Razor
  • Losses of up to 39% of R-Value due to thermal bridging when fully compressing 100mm glass wool blanket
  • Inconsistent level of roof line
  • Safety mesh cannot be pulled tight
  • Not compliant with Section J of the BCA
  • Creates a thermal bridge, refer calc 338.1cB
  • Achieves total R-Value as low as R1.96
  • Losses of up to 6% of R-Value due to thermal bridging when using a 38mm wide x 90mm high pine spacer
  • Central fixings can lead to instability
  • Fully compressed wool packer is at risk of deterioration over time with the movement of the roof
  • Satisfies Section J of the BCA
  • LHL tested
  • Robust, consistent, safe and cost effective
Thermal prediction on request


Roof Razors are supplied in bundles of 6 preassembled units with screws pre-loaded into the legs.


Roof Razor fasteners are designed specifically for fastening the Roof Razor to steel purlins. For the standard Roof Razor 12 gauge, 14 TPI, class 4 coated screws in 80mm or 100mm length are pre-loaded into the legs. For cyclonic regions, 14 gauge, 10 TPI, class 4 coated screws in 80mm length are pre-loaded into the legs.