Board-on-Board Fence Calculator

A fence typically consists of vertical boards or pickets attached to horizontal rails and located a distance apart, leaving gaps that allow air and light to pass through.

For total privacy, we can leave zero gaps between the pickets. Nevertheless, there's an issue: the wood can shrink, diminishing the width of the pickets and creating new openings. Fortunately, the board-on-board wood fence solves that.

In a board-on-board wood fence, we place each picket on top of another to compensate for future shrinkages.

For a board-on-board fence, we calculate the posts, rails, and sections (panels) as in a conventional fence (look at the formulas in our fence calculator).

The difference relies on how we calculate the number of pickets:

In the previous formula:

• You must input the fence length, picket width, and picket overlap all in the same units.
• If you obtain a decimal, round it up to the nearest integer (e.g., 4.6 ≈ 5 and 4.1 ≈ 5).

🙋 tl;dr. Multiply the picket width by 0.24, and you'll get the recommended overlap.

• We recommend using a picket overlap at least two times the expected width shrinkage.
• In the worst case, that shrinkage will be 12% of the width.
• Therefore, the rule of thumb is to use a picket overlap of 24% of the picket width.
• Of course, that space must be enough to join the adjacent pickets.

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