How the New Standards for Pressure-Treated Lumber Will Affect You

dec-10 Recently, the American Wood Protection Association (AWPA) raised its U1 standard for preservative-treated lumber in certain above-ground applications.

When officially adopted by building codes, the new standard will require UC4B-treated lumber to be used in above-ground applications where wood will be:

  • Located less than 6 inches from the ground
  • At risk of getting poor air circulation
  • Difficult to maintain, repair, or replace
  • Essential to the performance and safety of the entire construction
  • In prolonged contact with damp leaves or other vegetation
  • Consistently exposed to moisture
  • Used in a tropical climate

Deck joists, beams, and ledger boards will have to be UC4A ground contact material.
Posts, stair stringers, and certain deck board installations will also require ground-contact treated lumber.

Typically, there’s lag time between when recommendations are made and when building codes adopt them. Local municipalities will decide when their inspectors will enforce the new rules. At some point, however, this change will be effective everywhere. Ultimately, we expect that it will become the de facto requirement for framing and that lumberyards
will only carry heavier-duty lumber.


With the higher standards will come increased cost to you and your customers
as you need to buy more of the expensive, heavier-duty lumber.

However, there also is a positive side to these changes.

The new standards will provide customers with the benefits of better
quality, enhanced durability, less maintenance, and increased safety.
Those are strong selling points!

For more information about when the new standards will be incorporated into building codes in the areas you serve, contact the local municipalities in those jurisdictions