Application Standards
CHOOSING THE RIGHT PRESSURE-TREATED LUMBER FOR YOUR PROJECT IS ESSENTIAL.
We’ve broken down a few commonly seen standards to help you choose the correct lumber for your project.
To put it simply, consider the following when selecting your lumber. The end tag will show one of these Use Category Designations:
- UC3B: Above ground
- UC4A: General above ground/ground contact and freshwater use
- UC4B: Ground Contact/structural use, for critical structural, ground contact, fresh water and saltwater use
When to use UC3b (Above Ground):
*Not suitable for deck joist or near ground uses. Specify and use ground-contact pressure treated lumber in these applications.
Wood treated to (UC3B) above-ground standards is ideal for use in light-duty situations where wood will not be in contact with moisture or the ground.Examples:
- 2x4 or 2x6 railings
- Certain deck board installations
Above-ground contact lumber applications must adhere to UC4A requirements when wood is used in the following scenarios:
- Difficult to maintain, repair or replace (such as deck joists and ledger boards) and are critical to the performance and safety of the entire system/construction
- Installed less than 6 inches from the ground
- At risk for poor air circulation (little airflow)
- Likely to have prolonged contact with vegetation or damp leaves
- Exposed to frequent moisture
- Used in tropical climate
WHEN TO USE LIGHT DUTY:
Light Duty covers an internal standard that we treat to that we call UFPB. It not meant for structural uses (not critical to the integrity of a structure) and does not conform to the AWPA/ESR standards. It is easily replaced and maintained and is generally backed by a 1-year warranty (some products 10 - 20 years). Lumber with a Light Duty designation can be used in above ground and in some ground contact settings. This can be used for West Virginia split rail fencing, any RP/DF/non-KD SYP fencing products/components, any specialties (spindles, lattice, etc.) and round posts.
When to use UC4A (Ground Contact):
Wood treated to (UC4A) ground contact standards is ideal for general-use situations where the wood may contact moisture, the ground, or be installed in a manner that subjects the wood to comparable ground contact conditions – such as poor ventilation, tropical climates or frequent exposure to moisture.
Examples:
- Deck joists
- Beams
- Ledger boards
- Posts
- Stair stringers
- Certain deck board installations
Ground contact lumber applications must adhere to UC4A requirements when wood is used in the following scenarios:
- Difficult to maintain, repair or replace (such as deck joists and ledger boards) and are critical to the performance and safety of the entire system/construction
- Installed less than 6 inches from the ground
- At risk for poor air circulation (little airflow)
- Likely to have prolonged contact with vegetation or damp leaves
- Exposed to frequent moisture
- Used in tropical climate
WHEN TO USE UC4B (Critical Structure):
Wood treated to (UC4B) heavy-duty standards should be used in very severe environments or for critical structural components such as foundation piling. Always consult local building codes for additional requirements for specific structures. This should be considered when the wood will be used to support a permanent structure.
Examples:
- Heavy-duty projects or functions
- Difficult to replace or maintain
- Supporting a permanent structure
- Exposure to saltwater spray
- Extreme/tropical climates
- Supporting a dock, pier or marine structure, not in salt water but above it
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How do I know if the treated wood I'm using is properly treated for my intended use?Look for a lumber end tag. Each piece of ProWood lumber has a tag containing information regarding the preservative used, the appropriate end use (i.e. above-ground or ground contact), the quality standard and safe handling instructions.
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Are there different types of ProWood for different applications?Yes. Our tags will always state "above ground only" or "ground contact" so you can be sure you are using the right material for the job. ProWood products containing higher levels of preservatives are available for special purposes such as projects requiring extensive moisture/earthen contact –– including foundations, pole barns, docks and culverts. For more details, refer to the Understanding the End Tag page.
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Why use ProWood pressure-treated lumber?Lumber's greatest enemy is biological attack — destruction by termites, fungi and marine borers — as well as damage from rain, sun and wind. Thanks to over 50 years of research, ProWood can stand up to every threat for decades of use.
