Our most common type of wood used to build fences in harsh weather areas (like Western New York) is pressure-treated southern pine. There are many different chemical preservatives and processes used to treat exterior wood products. The main idea behind these processes is to increase the durability of the wood against exterior conditions, including solar and UV rays, moisture, and termites. The main chemical process used to treat the pressure-treated wood we use to build our fences is called ACQ (Alkaline Copper Quaternary). To save you most of the technical mumbo-jumbo, this process combines copper (a fungicide) with another chemical, which acts as an insecticide. Even though this newer process uses less harmful compounds than older pressure-treating processes (such as those that used arsenic), pressure-treated wood should still not be burned, and care should be taken when handling the wood.
Photo: 6-foot-high dogear pressure-treated wood fence
Photo: 6-foot-high dogear pressure-treated wood fence on steel posts
Photo: 3-foot high spaced picket pressure-treated wood fence with French gothic posts
Photo: 3-foot-high dogear pressure-treated wood fence
Photo: 4 foot high straight-top dogear fence with flat top posts
Photo: 6 foot high straight-top dog-ear fence with French Gothic posts
Photo: 6 foot high straight-top dog-ear fence with French Gothic posts
Photo: 6 foot high straight-top dog-ear fence with flat top posts
Photo: 6 foot high pressure treated wood on black steel gate
Photo: 6 foot high concave fence with French Gothic post tops
Photo: 6 foot high privacy fence with 2×4 top cap
Photo: 6 foot high privacy fence with 2×4 top cap
Photo: 3 foot high pressure treated spaced picket fence. Gothic top pickets and posts
Photo: 3 foot high, 1×4 pickets, Gothic tops
Photo: 4 foot high, spaced picket and 6 foot high solid