Cut two pressure-treated 4 by 4s to a length of 6 feet for the ... Cover the rear wall with 1/2-inch CDX plywood from the ...

Pressure-treated lumber ... one made of untreated Douglas-Fir lumber, and a second made of Douglas-Fir treated with Copper Azole (CA-C): Soil and plants within 3-4" of the wood frame were tested ...