Board On Board Fence Calculator

Board-on-Board Privacy Fencing Carpentry Standards

Board-on-board (also called shadowbox or overlapping privacy) places alternating wood pickets on top of each other with a 1.0-inch to 1.5-inch overlap so that when lumber inevitably dries and shrinks, zero sightline gaps appear:

• Nominal 1x6 Picket: Actual width is 5.5 inches. With a 1.0 inch overlap, the effective coverage is 4.5 inches (0.375 ft).

• Base Pickets = Fence Length (ft) × 124.5 in

• Post Count (8-foot on center): Sections = Length8 , Posts = Sections + 1

• Horizontal 2x4 Rails: 3 rails for 6 ft fence, 4 rails for 8 ft fence (3 rails × sections × 1.10 waste)

• Concrete Mix: 2 bags (50 lb or 60 lb fast-setting) per 4× 4 post hole.

How to Use This Calculator

Enter your Total Fence Length (Linear Feet) (e.g. 100), Fence Height (Feet) (e.g. 6), Picket Nominal Width — choose from 6-Inch Nominal (5.5" actual width), 4-Inch Nominal (3.5" actual width), Picket Overlap (Inches) (e.g. 1.0), Post Spacing On-Center (Feet) (e.g. 8), Number of Horizontal 2x4 Rails — choose from 2 Rails (4 ft - 5 ft Fences), 3 Rails (Recommended for 6 ft Privacy), 4 Rails (Heavy-Duty / 8 ft Privacy), Wood Cutting Waste Allowance (%) — choose from 5% (Standard Cutting Allowance), 10% (Recommended Lumber Culling), 15% (Custom Slopes & Culled Boards), and Estimated Material Cost per Foot () (e.g. 24.00). Measure twice before entering dimensions — small measurement errors scale up significantly in material estimates.

The Formula

Actual picket width: 6-in nominal = 5.5 in, 4-in nominal = 3.5 in

Worked Example

A 100-foot run of 6-foot tall cedar board-on-board fence with 1-inch overlap requires 294 dog-ear pickets and 14 posts set 8 feet on center in 28 bags of concrete.

Understanding Your Result

Fence posts are typically set 1/3 of total post length below grade (6-foot post requires 2-foot hole). Post spacing: 6–8 feet on center for wood, 6 feet for vinyl panels (most pre-made sections). Minimum post concrete depth: 24 inches in USDA Hardiness Zones 6 and above; 30 inches for Zones 4–

• Dig below the frost line to prevent heaving — check local frost depth requirements. Add 10% waste factor to linear footage for overlap and end posts.