Board on Board Fence Calculator for Privacy Fences

Board on Board Fence Calculator

A board-on-board fence overlaps pickets so shrinkage does not open gaps in a privacy fence. Enter fence length, post spacing, height, picket width, and overlap to get post count, section count, picket count, and rail count.

Picket count formula

With fence length, picket width, and overlap in the same units:

$$n_{pickets} = \left\lceil \frac{L - w_p}{w_p - o} + 1 \right\rceil$$

Posts and sections follow standard fence layout: sections equal the ceiling of length divided by post spacing, and posts equal sections plus one.

Recommended picket overlap

Wood pickets can shrink up to about 12% of their width as they dry. A common rule uses overlap equal to 24% of picket width so gaps stay closed after shrinkage. For a 5.5 inch picket that is about 1.3 inches of overlap.

Frequently Asked Questions

Why use a board-on-board fence?

Overlapping pickets block sight lines even when boards shrink over time. Solid privacy fences with no overlap can develop visible gaps as wood dries.

How much overlap do I need?

Use at least 24% of picket width as a starting point. Narrow pickets may need 1 inch overlap while wide boards may need 2 to 3 inches.

How many pickets fit in an 8-foot section?

It depends on picket width and overlap. A 5.5 inch picket with 1.5 inch overlap needs about 24 pickets per 8-foot run. Use the calculator for your exact dimensions.

How long should fence posts be?

Posts are typically fence height plus 2 feet buried below grade in imperial layouts. Deeper posts improve stability in windy areas or sandy soil.

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Board on Board Fence Calculator