Part 1 of a 10-part Series: AWPA Use Categories and End Tags

10/28/21 Part 1. AWPA Category uses of treated wood and end tags explained

What preservatives are in pressure treated wood?

  • There are different preservatives for lumber treated for ground contact, above ground, lake and marine uses.
  • All preservatives standardized by the American Wood Protection Association (AWPA) are registered pesticides regulated by the EPA. The AWPA Book of Standards categorizes preservatives by their intended use with the required minimum preservative retention levels.

The infographic below shows common residential projects and the applicable Use Category for the specific exposures.

AWPA Treated

Be sure to check the end tags.

The end tag designates the following information.

  1. AWPA U1 – this shows the preservative is listed in the AWPA Standards
  2. AWPA (UCS) Use Category – Includes Name and UCS Abbreviation Code
  3. Preservative code: EL2, CA-C, CA-B for example
  4. Preservative Name is Optional: Ecolife, Copper Azole Type C, Copper Azole Type B for example
  5. Preservative retention – the amount of preservative retained in the wood
  6. CheckMark and Inspection agency logo – if the treating plant subscribes to third-party quality control, you will see the logo of an agency accredited by the American Lumber Standard Committee and usually a “CheckMark” logo to make it easier to locate the agency logo.
  7. Manufacturer and Location – Name of treater and location of treating plant.

More details on AWPA standardized preservatives

Topics covered in our 10-part series

Part 1. 10/28/21
AWPA Category uses of pressure treated wood and end tags explained


Part 2. 11/04/21
Common treated wood sizes in nominal and actual dimensions plus popular project plans

Part 3. 11/11/21
Hardware and installation tips including field treatment for end cuts
Part 4. 11/18/21Staining treated lumber

Part 4. 11/18/21
Staining Treated Wood

Part 5. 11/25/21
Care and maintenance


Part 6. 12/02/21
Tips for shoveling snow and ice removal on wood decks


Upcoming Topics

Part 7. 12/09/21
Safe handling

Part 8. 12/16/21
Research on treated wood used in raised garden beds

Part 9. 12/23/21
How wood is pressure treated

Part 10. 12/30/21
How to interview contractors and check references

If you have missed a topic or have suggestions for other treated wood related subjects, let us know.

For quick answers and more tips, click here.