DPWES Letters to Industry

Land Development Services
12055 Government Center Parkway
Fairfax, Virginia 22035
703-324-1780, TTY 711

February 3, 2004

Pressure-Treated Lumber

On January 1, 2004, the wood preservative industry began the phase out of a variety of pressure-treated wood that contains arsenic (CCA). The new alternative wood preservative methods (ACQ, CA and CA-B) will affect all residential uses of pressure treated lumber including sill plates, fences, and especially decks. Learn more information from the U.S. Environmental Protection Agency.

As tested and as reported in numerous publications, including one from the National Association of Home Builders, chemicals in the new methods will prematurely corrode standard fasteners, hardware, and flashing that were previously acceptable with CCA pressure-treated lumber. Industry, wood preservers, and the building code community have responded with requirements to ensure that metals in contact with pressure-treated lumber will not deteriorate. The table below outlines the specific requirements for components associated with pressure-treated lumber. These products are available at most home center stores and lumber supply yards. Please note in all cases, electroplated galvanizing is NOT acceptable.


Nails, screws, lag screws, and bolts (steel bolts 1/2" diameter or greater are exempt)

Hot-dipped zinc galvanized, stainless steel, or approved for use with ACQ, CA or CA-B

Hardware  (joist hangers, anchors, clips, and angles)

Hot-dipped galvanized with a 1.85 oz/sf of zinc (G-185 coating), or stainless steel (type 304 or better). Look for products such as "Zmax" from Simpson Strong-Tie or "Triple Zinc" from USP.
Flashing Copper, stainless steel, silicon bronze, UV-resistant plastic

The Fairfax County Typical Deck Details have been revised to include the requirements listed above. Fairfax County residential inspectors will be requiring verification of the approved products' installation in the field. It is important that data related to the metal components not readily identifiable by observation be retained on the project site. If plastic is used as flashing, the UV resistance of the plastic must be verified as well.

For more information, please contact Brian Foley, Chief Structural Engineer, at 703-222-0114, TTY 711 or via e-mail.

*Treatment Methods:

CCA: Chromated copper arsenate

ACQ: Ammoniacal copper quat

CB-A, CA: Copper azole

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