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Treated X-Beam

Rosboro Treated X-Beam is simply our Douglas fir, architectural appearance X-beam that is treated with Hi-Clear II™ a clear industrial wood preservative that leaves the beam an attractive honey-color. The preservative treatment protects against decay, mold, bacteria, and insects, including the Formosan termite.

Treated X-BeamBacked with a 25-year warranty, Rosboro Treated X-Beam products are an excellent choice for above ground applications such as decks, porches, and balconies where appearance is critical.

Hi-Clear II is non-corrosive to metal, however we recommend using hangers and fasteners specified for treated wood products, such as hot-dip galvanized or stainless steel. Oil-based stains and paints can be applied as a final finish once the treatment has flashed off.

Design Values:

 Attribute Value
 Layup Combination 24F-V4
 Flexural Stress Fb (psi)2
 Tension Zone
 Flexural Stress Fb (psi)2 -
 Compression Zone
 Compression Perpendicular
 to Grain Fc1 (psi)
 Shear Fv (psi)3 265
 MOE (106 psi) - Apparent 1.8
 MOE (106 psi) - True 1.9


  1. Fb shall be adjusted by the volume effect factor using the following formula: Cv = (5.125/b)1/10 x (12/d)1/10 x (21/L) 1/10 < 1.0 where: b = beam width (in), d = beam depth (in), L = beam length (ft)
  2. For non-prismatic members, notched members, members subject to impact or cyclic loading, or shear design of bending members at connections (NDS-05, the design shear (Fv) shall be multiplied by a factor of 0.72.
  3. The Fv values do not include adjustments for checking.


  • Inventoried Widths: 3-1/2" and 5-1/2"
  • Inventoried Depths: (IJC) I-Joist compatible depths 9-1/2", 11-7/8", 14", 16" and 18"

Handling, Finishing, Maintenance and other Technical Information:

  1. Field Treatment
  2. How to Finish
  3. Periodic Maintenance
  4. Restricted Uses and Precautions
  5. Proper Design and Construction


1. Field Treatment

All field cuts, holes or beam damage that occurs after treatment must be field treated to protect the exposed wood material. Application of a copper naphthenate solution having a minimum 2% metallic solution is specified in accordance with AWPA Standard M4. Some of the 2% (metal) products that are currently available are:

  • Cupernol – Green #10
  • Wolmanized – End Cut Solution
  • Jasco – Ternin-8, Copper Green, Copper Brown

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2. How to Finish

Rosboro Treated X-Beam may be finished or stained after thorough air drying has occurred and the mineral spirit carrier has flashed-off. A quality oil based finish should be used to assure proper adhesion and performance. Consult paint suppliers or manufacturer for product recommendations. It is a good idea to apply the finishing product to a small exposed test area to insure that the product provides the intended result.

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3. Periodic Maintenance

Although pressure-treated wood is protected against rot (fungal decay) and termites, periodic maintenance must be performed to maximize protection against weathering. Any exposed wood weather pressure treated or not, should be protected with a high quality water repellent finish or stain to help reduce warping, checking, and splitting.

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4. Restricted Uses and Precautions

Rosboro Treated X-Beam and Column products should not be used in marine applications such as docks, marinas, and standing-water conditions. The treatment used for Rosboro Treated X-Beam is low in toxicity to humans, however gloves should be worn when handling treated products, and dust masks and eye protection should be worn when cutting treated beams and columns. Always follow site, handling, and disposal instructions provided by Materials Safety Data Sheets (MSDS) available on our technical reference page.

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5. Design and Construction Considerations

Design: Pressure treated wood is not entirely immune to rot and decay. Thoughtful design detail and construction practices will extend the life of any structure. For instance poor design can create collection zones for organic matter such as dirt and leaves that can cause moisture to collect and become trapped. Organic matter can collect in cracks and in between poorly detailed or flashed connections creating a perfect environment for fungi growth. At the design stage, every effort should be made to allow for ventilation or air circulation and water to shed off - this is particularly critical at connections.

Construction: Preservative treatment creates an envelope of protection around the wood. Field fabrication involving cutting, notching or drilling after treatment breaks this envelope, exposing untreated wood to attack by decay fungi and insects. Decay potential in field-drilled holes and sawn surfaces can be reduced with proper field treatment of the cut surfaces during construction; however, wood treated in the field is less resistant to decay than wood treated by pressure processes.

A more effective prevention method involves fabrication (cutting and boring) prior to preservative treatment. This practice results in thoroughly protected wood, reducing the risk of decay, minimizing potential maintenance costs, and reducing the time required for field erection. Timber members should be fabricated before preservative treatment whenever practical. The AWPA recommends field application of a copper naphthenate solution on field fabricated treated wood as specified in accordance with AWPA Standard M4.

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