Board-on-Board Fence Calculator

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Welcome to this board-on-board fence calculator, a tool created to know:

How many pickets a board-on-board fence needs;
How many sections (aka panels) the board-on-board fence requires in total; and
Many more!

Keep reading this article to learn more about board-on-board privacy fences, the formulas, and how they differ from conventional fences.

Differences between conventional and board-on-board privacy fences

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.

Formulas for board-on-board fence calculation

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:

\scriptsize \begin{gather*}\rm Number\ of\\[-4px]\rm pickets \end{gather*} = \frac{\begin{gather*}\rm Fence\\[-5px]\rm length \end{gather*} - \begin{gather*}\rm Picket\\[-5px]\rm width \end{gather*}}{\begin{gather*}\rm Picket\\[-5px]\rm width \end{gather*} - \begin{gather*}\rm Picket\\[-5px]\rm overlap \end{gather*}} + 1

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).

Picket overlap

🙋 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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FAQs

How much overlap a board-on-board fence needs?

The recommended picket overlap for a board-on-board fence ranges from one to three inches, depending on the picket width and wood shrinkage:

For a 3½" picket width, a 0.8" overlap will be enough;
For a 5½" width, a 1.3" overlap is ok; or
For an 11½" width, you can use a 2.8" overlap.

How many pickets per 8-foot section my board-on-board fence needs?

To know how many pickets per 8-foot section your board-on-board fence needs, consider the width and overlapping:

If you use pickets of 5½" width with a 1½" overlapping, you need 24 pickets per section;
If you use pickets of 3½" width with a 1" overlapping, you need 38 pickets per section; and
For other widths or overlappings, use our board-on-board fence calculator.