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Boards, spacing, posts and rails for a good-neighbour fence.
With these inputs:
| Result | Value |
|---|---|
| Total boards | 429 |
| Boards needed (with waste) | 429 |
| Boards per linear ft | 2.67 |
| Boards per 8 ft section | 22 |
| Gap between boards on each face (in) | 3.5 |
| Posts | 20 |
| Rails | 57 |
| Screws (approx.) | 2832 |
| Board cost | $1,716 |
Shadow box looks identical from both sides, which is why it is often the style HOAs and neighbours agree on. It is not a full privacy fence.
Shadow box hangs boards on alternating faces of the rails. Each board laps its neighbours on the opposite face, so the run advances by the board width minus one overlap for every board. That leaves an open gap on each face which the boards on the other face cover head-on — which is why it reads as solid from straight ahead and open from an angle.
Advance per board = board width − overlap · Boards = ⌈(run ft × 12) ÷ advance⌉ × (1 + waste %)
About 2.67 boards per linear foot using 5.5 inch boards with a 1 inch overlap — that is roughly 267 boards for a 100 ft run before waste. An 8 ft section takes about 22 boards, alternating 11 on each face. Add 10 percent for cuts and rejects.
A wood fence with boards fastened to alternating sides of the rails, each one overlapping the gap left by its neighbours on the opposite face. From straight on it looks like a solid fence; from an angle you can see through the offset gaps. It is often called a good-neighbour fence because both sides look the same.
Partly. Head-on there is no sightline, but walk along it and the offset gaps open up. It blocks the casual view from a neighbouring window and does not block the view from someone standing at an angle to it. If full privacy is the goal, a solid or board-on-board fence is the right choice.
The gap on each face equals the board width minus twice the overlap. With 5.5 inch boards lapping 1 inch, each face has 3.5 inch gaps, and the boards on the other face sit behind them. A wider overlap narrows the gaps and uses more boards.
They use the same number of boards for the same overlap. Board-on-board puts both layers on one side, giving full privacy but a finished face and a rail face. Shadow box splits the boards between the faces, giving matching sides and airflow but only partial privacy. Pick on whether privacy or a shared appearance matters more.
It tends to, for two reasons. Air moves through it so the boards dry after rain instead of staying damp against a neighbour, and it does not catch wind like a solid panel, so the posts take less load in a storm. The framing is otherwise identical.
Three on a 6 ft fence. The boards hang on alternating faces, so each rail carries board weight on both sides, and the fasteners on one face sit between the fasteners on the other. Two rails will let a 6 ft shadow box fence sag and twist.
Yes, and it is worth doing. A cap rail across the top ties the two faces together, stops individual boards cupping or twisting outward, and hides the end grain, which is where wood fences take on water first. It adds a trim board and a few hours.
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