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Working With MicroPro Sienna

MicroPro Sienna® Treated Wood products are pressure treated with MicroPro® Micronized Copper Azole (MCA) to protect the wood against fungal decay and termite attack. The main ingredient in the preservative system is copper, which has long been known as an effective wood preservative. MicroPro Sienna uses micronized copper coupled with micronized tebuconazole for long-term protection of wood exposed in exterior applications.

Safe Practices – When working with MicroPro Sienna or any other treated wood product:

  • Wear gloves when working with wood.
  • Only treated wood that is visibly clean and free of surface residue should be used.
  • Some preservative and/or pigment colour may migrate from the treated wood into soil, water or other surfaces. It may also dislodge from the treated wood surface upon contact with skin. Wash exposed skin areas thoroughly.
  • Wash exposed skin areas thoroughly. Wash work clothes separately from other household clothing before reuse.

Cut ends / Field cuts – When building your outdoor project with pressure treated wood it is important to protect the cut ends, large drill holes, and other field cuts.

  • For pressure treated timbers and for pressure treated wood used in ground contact applications, a brush on end-cut wood preservative is required at the time of construction on all saw cuts, large drill holes and other field cuts. Two applications of a copper naphthenate based end-cut preservative must be applied to the treated wood before it is installed. Follow the manufacturer’s directions for proper application.
  • For pressure treated wood used in above ground applications, such as deck boards, railings, post tops or fence boards, a brush on end-cut wood preservative or Timber Specialties Cut-N-Seal® product should be applied to all saw cuts, large drill holes and other field cuts at the time of construction. Follow the manufacturer’s directions for proper application.

Fasteners & Aluminum – MicroPro Sienna treated with MicroPro technology exhibits corrosion rates on metal product similar to untreated wood. Use fasteners and hardware designed for exterior construction that are in compliance with the manufacturer’s recommendations and the building codes for their intended use. MicroPro Sienna Treated Wood products can be used in direct contact with aluminum building products in above ground applications where the wood is not exposed to frequent and prolonged wetting. See Fastener and Hardware Information.

When appearance permits, attach boards bark side up – As a general rule, attach boards bark side up (annual rings arc upward). However, also inspect deck boards before installation and take notice of any knots or defects that could become an issue as the wood dries out and turn that side down. Ensure boards are securely fastened to help prevent warping.

Pilot holes – Drill pilot holes to minimize splitting especially when nailing or screwing near the edge or end of a board.

Deck board spacing – Deck boards can be expected to shrink slightly in width as they dry, so many builders prefer to butt them tight together and allow drying and nature to create the spacing between them.

Covering / Enclosing – MicroPro Sienna treated wood should be allowed to properly dry before it is covered or enclosed with another building material, i.e., composite boards. Trapped moisture could lead to colour migration from MicroPro Sienna. Properly dry wood has a moisture content less than 19%. The moisture content of the wood can be checked with an electronic moisture meter.

Mold growth – Mold growth can and does occur on the surface of many products, including untreated and treated wood, during prolonged surface exposure to excessive moisture conditions. To remove mold from the treated wood surface, wood should be allowed to dry. Typically, mild soap and water can be used to remove remaining surface mold.


  • All sawdust and construction debris should be cleaned up and disposed of after construction.
  • Do not burn treated wood.
  • Do not use treated wood as mulch.
  • Users should dispose of treated wood scraps and cut offs in accordance with local, provincial and federal regulations.

Actual product colour may vary from colour shown in photos.
MicroPro Sienna Treated Wood products are produced by independently owned and operated wood preserving facilities.
MicroPro, MicroPro Sienna, and Cut-N-Seal are registered trademarks of Koppers Performance Chemicals Inc.