Guide to commodity specifications for treated wood end uses.

Use CategoryService ConditionsUse EnvironmentCommon Agents of DeteriorationTypical Applications
UC1Interior Construction above ground, Dry.Continuously protected from weather or other sources of moisture.Insects onlyInterior construction and furnishings
UC2Interior construction above ground, damp.Protected from weather, but may be subject to sources of moisture.Decay fungi and insectsInterior construction
UC3AExterior construction above ground coated & rapid water runoff.Exposed to all weather cycles, not exposed to prolonged wetting.Decay fungi and insectsCoated millwork, siding and trim.
UC3BExterior construction above ground, coated & or poor water runoff.Exposed to all weather cycles, including prolonged wetting.Decay fungi and insectsDecking, deck joists, railings, fence pickets, uncoated millwork.
UC4AGround contact or fresh water, non-critical components.Exposed to all weather cycles, normal exposure conditions.Decay fungi and insects.Fence, deck, and guardrail posts, crossties & utility poles (low decay areas).
UC4BGround contact or fresh water, critical components or difficult replacement.Exposed to all weather cycles, high decay potential including salt water splash. Decay fungi and insects with increased potential for biodeterioration.Permanent wood foundations, building poles, horticultural posts, crossties & utility poles (high decay areas).
UC4CGround contact or fresh water, critical structural components.Exposed to all weather cycles, severe environments, extreme decay potential.Decay fungi and insects with extreme potential for biodeterioration.Land & freshwater piling, foundation piling, crossties & utility poles (Severe decay areas)
UC5ASalt or brackish water and adjacent mud zone, Northern waters.Continuous marine exposure (salt water).Salt water organisms.Piling, bulkheads and bracing.
UC5BSalt or brackish water and adjacent mud zone NJ to GA, south of San Fran.Continuous marine expsure (salt water).Salt water organisms including creosote tolerant Limnoria tripunctata.Piling, bulkheads and bracing.
UC5CSalt or brackish water and adjacent mud zone South of GA & Gulf Coast.Continuous marine exposure (salt water).Salt water organisms includeing creosote tolerant Martesiz, Sphaeroma.Piling, bulkheads, bracing
UCFAFire Protection as required by codes. Above ground Interior construction.Continuously protected from weather or other sources of moisture.FireRoof sheathing, roof trusses, studs, joists and paneling.
UCFBFire protection as required by codes. Above ground exterior construction.Subject to wetting.FireVertical exterior walls, inclined roof surfaces or other construction which allows water to quickly drain.