Treating Cuts in PT

Building codes say that field-cut ends, notches, and drilled holes in preservative-treated wood must be field-treated in accordance with AWPA Standard M4. Within that standard, acceptable preservatives for exterior use are copper naphthenate and oxine copper (also known as copper 8 quinolinolate). Copper naphthenate is suitable for field treatment of wood in either ground-contact or above-ground exterior applications.