Which wood fence boards will last longer, pressure-treated-lumber or non-treated lumber that has a treatment applied after the fence is built?

Question

I just heard of the capability to build a fence with untreated lumber and to apply a disodium octaborate tetrahydrate solution after installation.

The alternatives I have been considering are AWPA UC3A pressure treated lumber (PTL) or cedar. My understanding is that both the PTL and the cedar require the application on an initial and periodic (every 3 years) wood preservative (not a stain).

I am looking for the best long-term wood fence solution and prefer to pay higher up-front costs to avoid maintenance and repair in the future.

(The decisions to use wood for the panels and metal for the posts have already been made. The wood panels will be 2 inches above grade and have no ground contact. The wood panels will have a cap on the top so that the grain ends of the boards are not exposed to the weather.)

Answer 1

Pressure-treated lumber should last longer. Any preservative applied to untreated wood would only affect the surface to a few mm inside, so would have to be reapplied more frequently.

Answer 2

Different factors are involved in understanding the lifespan of a wood fencing. In wood fencing, the most common choices are pine, spruce and cedar. The usual lifespan of any wooden fencing ranges from 15 to 30 years depending on the quality of the wood and how well it is taken care of, and of course, the spice that is used. The 15 to 30 years range is usually for the cedar, while for spruce it comes down to 4 to 7 years and pine lives for a maximum of 12 years. One more thing that you have to note is that treated wood, spruce and cedar, may live up to 20 years and the same might go up to 40 years in case of cedar. Without question, it is proven that when it comes to wood fence boards, cedar is the best choice, and stays for years after it is built.