How to Guide

Use Category (UC) information is found on the end tag or treatment stamp
Ground Contact, fresh water
UC4A – General use
1
UC4B – Heavy duty
UC4
Above Ground, exterior construction
UC3A - Coated, rapid water runoff
UC3B - Uncoated, poor water runoff
1
UC3
Interior Construction,
above ground, damp
UC2
Above Ground components that may be required to be preserved for ground contact include joists and beams
that are difficult to replace and critical to the structure or components that may be exposed to ground contact
type hazards due to climate, artificial or natural processes or construction.
NOTE: This is designed to help identify the appropriate Use Category for the intended use. Some commodities
may require a retention for a specific application beyond that suggested, due to the critical nature of their use.
The designer should use their best judgement to determine the appropriate specification for a particular use.
1
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SELECT THE RIGHT PRESERVED WOOD FOR YOUR PROJECT
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AMERICAN WOOD PROTECTION ASSOCIATION (AWPA) PRESERVED WOOD USE CATEGORIES
To ensure quality, check the end tag for
the third-party inspection mark next to
the CheckMark or ICC-ES Mark.
woodnaturally.com
preservedwood.org
FENCE PICKETS
ABOVE GROUND, PROTECTED
Use Category 3A or higher
PORCH FLOORING
ABOVE GROUND, PROTECTED
Use Category 3A or higher
FASCIA & TRIM
ABOVE GROUND, PROTECTED
Use Category 3A or higher
DECK RAILING
ABOVE GROUND
1
Use Category 3B or higher
LANDSCAPE WALL
GROUND CONTACT
Use Category 4A or higher
POSTS
GROUND CONTACT
Use Category 4A or higher
GARDEN BOX
GROUND CONTACT
Use Category 4A or higher
PERMANENT WOOD
FOUNDATION
GROUND CONTACT
Use Category 4B or higher
SILL PLATE
ABOVE GROUND
Use Category 2 or higher
DECK BOARDS
ABOVE GROUND
1
Use Category 3B or higher
STRUCTURAL
POSTS
GROUND CONTACT
Use Category 4A or higher
LEDGER
GROUND CONTACT
1
Use Category 4A or higher
SHAKES & SHINGLES
ABOVE GROUND
Use Category 3B or higher
JOISTS & BEAMS
ABOVE GROUND
1
Use Category 3B or higher
GROUND CONTACT
Use Category 4A or higher
STAIRS
ABOVE GROUND
1
Use Category 3B or higher
GROUND CONTACT
Use Category 4A or higher