# Board-on-Board Fence Calculator

*“Dimensional Shrinkage“*

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**:

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.

## Other similar tools

## FAQ

### 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.