Board On Board Fence
Calculate posts, sections, rails, and pickets needed for a board-on-board privacy fence. Enter fence length, height, picket width, and overlap for instant material estimates.
About This Calculator
Our board-on-board fence calculator helps homeowners, contractors, and DIY enthusiasts estimate the precise materials needed for building a board-on-board (shadowbox) privacy fence. Unlike standard fences that have gaps between pickets, a board-on-board fence alternates pickets on both sides of the rails, creating a solid, visually identical appearance from either side while accommodating natural wood shrinkage over time.
The calculator uses standard fencing formulas: number of sections = ceil(fence length / post spacing), posts = sections + 1, post length = fence height + 0.76 m (for concrete embedment), rails = sections × rails per section, and pickets = ceil((fence length in cm - picket width) / (picket width - picket overlap)) + 1. The recommended picket overlap is 24% of the picket width to compensate for wood shrinkage. All dimensions use metric units for consistency across global regions.
Regional Notes
India: Board-on-board fencing is less common but growing in popularity for residential properties in suburban areas. Boundary walls are typically built with brick or concrete, but wooden privacy fences are preferred in hill stations and resort properties. Posts should be set with concrete mix (1:2:4 ratio) and treated for termite resistance.
US: Board-on-board (shadowbox) fences are extremely popular for residential backyards, especially in suburban neighborhoods. Standard lumber dimensions follow imperial measurements — common picket widths are 5.5 inches (pressure-treated pine) and 3.5 inches (cedar). Posts are typically 4×4 pressure-treated lumber set 24-36 inches deep in concrete. Most US fence sections span 8 ft between posts.
UK: Closeboard and feather-edge fencing are more traditional, but board-on-board style fences are becoming popular for modern garden designs. Timber treatment is essential due to damp climate conditions. Standard panel widths are 1.8 m (6 ft) and posts are typically set in postcrete. Always check with your local planning authority for permitted development height restrictions, which are usually 2 m for boundary fences.
Features:
- Instant posts, sections, rails, and picket count calculations
- Picket overlap adjustment for wood shrinkage compensation
- Visual bar chart and doughnut chart breakdowns
- Shareable URLs with saved input values
- Region-aware defaults for India, US, and UK
- Mobile responsive for on-site measurements
Frequently Asked Questions
What is a board-on-board fence?
A board-on-board fence, also called a shadowbox fence, is a privacy fence where pickets are placed on both sides of the rails in alternating positions. This design eliminates gaps between boards, provides privacy from both sides, and allows for wood shrinkage without creating visible openings. It is one of the most popular styles for residential privacy fencing.
How many pickets do I need for a board-on-board fence?
The number of pickets for a board-on-board fence is calculated as: pickets = ceil((fence length - picket width) / (picket width - picket overlap)) + 1. For example, a 15m fence with 14cm pickets and 3.8cm overlap needs approximately 138 pickets. The overlap is typically 24% of the picket width to accommodate wood shrinkage.
How much overlap does a board-on-board fence need?
The recommended picket overlap for a board-on-board fence ranges from 1 to 3 inches (2.5 to 7.6 cm), depending on picket width. For a 5.5-inch (14 cm) picket, use about 1.3 inches (3.3 cm) overlap. For 3.5-inch (9 cm) pickets, use 0.8 inches (2 cm) overlap. A good rule of thumb is 24% of the picket width.
What is the standard post spacing for a board-on-board fence?
Standard post spacing for a board-on-board fence is 6 to 8 feet (1.8 to 2.4 meters). Posts are set in concrete footings buried below the frost line, typically 2 to 3 feet (0.6 to 0.9 m) deep. Closer spacing provides a sturdier fence, while wider spacing reduces material costs but may require stronger rails.
How many rails per section does a board-on-board fence need?
A board-on-board fence typically uses 2 to 3 rails per section. For fences up to 4 feet (1.2 m) tall, 2 rails are usually sufficient. For taller fences between 4 and 8 feet (1.2 to 2.4 m), 3 rails provide better support. The rails run horizontally between posts and carry the weight of the pickets.
What is the difference between a board-on-board fence and a standard fence?
In a standard fence, pickets are attached to one side of the rails with gaps between them. In a board-on-board fence, pickets alternate between the front and back of the rails, with each picket overlapping the adjacent one. This creates a solid appearance from both sides with no visible gaps. Board-on-board fences use approximately twice as many pickets as standard fences for the same section.
How deep should fence posts be set for a board-on-board fence?
Fence posts should be set at least 2 feet (0.6 m) deep for fences up to 6 feet (1.8 m) tall, and 3 feet (0.9 m) deep for taller fences. The post hole should be three times the post diameter wide. Use concrete around the post for stability, ensuring it extends above ground level to shed water. Always check local building codes for frost depth requirements in your area.
What materials are best for a board-on-board fence?
Cedar and pressure-treated pine are the most common materials for board-on-board fences. Cedar is naturally rot-resistant and ages to a beautiful silver-gray, while pressure-treated pine is more affordable but requires staining or sealing. Composite materials are also available but cost more. For posts, always use pressure-treated lumber rated for ground contact, and use galvanized or stainless steel hardware to prevent rust.