"Field-cut ends, notches and drilled holes of preservative-treated wood shall be treated in the field in accordance with AWPA M4"
Preservative-treated wood "Lumber, timber, plywood, piles and poles supporting permanent structures required by Section 2304.12 to be preservative treated shall conform to the requirements of the applicable AWPA U1 and M4 for the species, product, preservative and end use."
"Lumber, timber and decking used in structural applications shall be field treated in accordance with Section 6.1 when cut or drilled during construction."
"Copper Naphthenate preservatives containing a minimum of 2.0% copper metal"
Always use Tenino Copper Naphthenate (2% as metal) when treating cuts to satisfy AWPA Standard M4. And comply with building codes.
Treated Wood Warranty Protection
Pressure treated such as MicroPro, LifeWood, EcoLife, AC2, Wolmanized, EraWood and others have warranties which exclude coverage when cuts, holes, etc. are not field treated with a brush on end cut solution during construction. Each warranty's language differs (see specific products warranty for exact language), in most instances Tenino Copper Naphthenate with 2% metallic copper fulfills the warranty exclusion clause for field treatment. If your lumberyard or building supply store doesn't carry Tenino 2% Copper Naphthenate, protect your investment and demand Tenino whenever you use pressure treated wood or lumber with a limited warranty.