Open Shutters A natural fit for Australian living

Specifications: Cedar

When architects, designers and builders were asked why they chose Western Red Cedar* their replies were:

Good looks and aesthetically pleasing – 33%
Natural Durability – 27%
Stable – 14%

Open has been using Cedar as its preferred material for the natural qualities of this sustainable timber we source from eco-managed forests in British Columbia. It is twice as stable as other conifers and its superior resistance to warping, cupping and twisting makes it ideal for use in both shutter blades and frames.


  • Western Red Cedar is classed High for durability, at around 41-60 years.
  • It also has the lowest shrinkage ranking with very low tangential (3.0%) and radial (0%-2%) reductions in measurement from unseasoned to 12% moisture content.
  • The heartwood contains extractives (Thujaplicans and Phenolics), that are toxic to decay-causing fungi.

Flame retardance specifications of Cedar

  • Western Red Cedar falls into the Australian Fire Properties Group 3.
  • Ranked in the middle of the Slightly Combustible category of timbers.

Flame spread and smoke development ratings

  • Western Red Cedar’s has an EFH Smoke-Developed Index rating of 4 out of 10, the lower the number the better the material.
  • Flame spread and smoke development classifications are far superior than minimum building code requirements.
  • The surface burning characteristics are used to regulate and control the rate of flame spread in case of fire, and lower ratings indicate more resistance to the spread of fire.
  • These ratings permit Cedar to be used in many interior applications without treatment.
  • Western Red Cedar has an Australian class II rating of 69, compared with Canadian and American code requirements of 150 and 200 respectively.
  • The smoke development classification for Western Red Cedar is 98, compared with Canadian and American code specifications of 300 and 450, respectively.

Termite resistance

  • Western Red Cedar has an in-built resistance to termites because of a naturally occurring preservative.
  • Not susceptible to Lyctid Borer

Acoustic properties

  • Western Red Cedar reduces or confines noise when used on the interior of windows and as doors and dividers.
  • The open cell structure of the timber is able to absorb and dissipate sound energy.
  • The cell structure converts the sound energy into heat by friction and viscoelastic resistance.

Gluing properties

    • A lack of pitch and resin makes Western Red Cedar receptive to glue bonds from a wide range of adhesives, This includes glue, laminate or external joinery.
    • This allows real versatility and great applications, such as Fingerjointed Cedar Siding.

      Insulation properties of cedar

      Open cedar shutters have been shown to reduce heat transfer by 47%. See more on the insulation qualities and  R-values of cedar here.

      *Source: Forest & Wood Products Australia Questionnaire, 2008