How long do fence panels last?

The lifespan question is really two questions wearing one coat. Panels and boards weather from the outside in, slowly and visibly, and you can see them going. Posts rot from the inside out at a single band of ground about 50mm either side of the soil line, where the timber is repeatedly soaked and then dried. That band is where nearly every fence we are called to has failed. It is why a fence can look perfectly sound from the patio and still be one gust from lying flat.

Treatment cadence is the difference between the two ends of the range. Published guidance is a preservative or exterior stain every two to three years, and a fence that gets it lands at the upper end. A fence that never gets touched again after installation day lands at the lower end, whatever it cost. Dip-treated panels are the ones to watch: manufacturers who dip rather than pressure-treat specify annual retreatment and state plainly that dip-treated timber must not sit in direct ground contact.

Construction matters as much as chemistry. Closeboard is built on site from vertical feather-edge boards nailed to horizontal arris rails, so it holds its shape and sheds water down the face of the boards. A lap panel is thin horizontal slats pinned into a light frame, which flexes in wind and traps water on every upward-facing lap. Both are timber, and both are treated, and one reliably outlives the other.

The practical way to buy the long end of the range: concrete posts and a gravel board so no timber ever touches soil, pressure-treated rather than dip-treated boards, and a stain every couple of springs. Do that and the structure outlives the boards, so when boards eventually go you replace boards rather than a fence. Skip the gravel board and you have bought the short end of the range at nearly the full price.

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