David M. Wilcox
Registered Professional Engineer

Further to your request and the detail provided for the Malibu Security Blade, we confirm as follows.

In the first instance we note that the drawings provided indicate that the louvre blade is 70 mm long and 8.0 mm in overall depth. We understand that the section is fabricated from 1.2 mm thick aluminium alloy 6063-T75, with minimum yield strength of 111 MPa.

Subsequently the capacity and deflection of the louvre blade has been calculated for wind regions A, B, and Cyclone Region C in accordance with the requirements of AS1170.2.

We note that the maximum blade spans calculated below are applicable to a maximum height of 25 meters above ground level.

Wind Regions A and B (Basic wind speed Vp=41 m/s)

For wind regions A and B, for use at height no greater than 25 metres above ground level for all terrain categories, the Malibu Security Blade has adequate strength for a maximum span of 900 mm. The corresponding deflection at this span is calculated at 8.5 mm.

Wind Region C (Basic wind speed = 57 m/s)

For cyclonic wind region C, for use at a height no greater than 25 metres above ground level for all terrain categories, the Malibu Security Blade has adequate strength for a maximum span of 600 mm. The corresponding deflection at this span is calculated at 3.5 mm.

We also have reviewed the capacity of the Malibu louvre blade assembly for use as part of a cyclone shutter capable of preventing impact from the object as defined in AS1170.2 Clause 3.4.7 from striking the window behind the louvre. We note that in this regard the loading required by the code is severe and exceeds the practical use of the louvre blade.

Further we note that the above assessment has been based on the capacity of the louvre blade section only. The overall capacity of the shutter frame is dependent upon the framing members and millions used and the spacing and capacity of the particular fixings.

We trust the above provides the information required at this time. Should you have any questions, please don't hesitate to contact the undersigned.

Yours Faithfully,


David Wilcox
BE(Hons 1) MIEAust CPEng
NPER - 3 (Civil, Structural)