Close Board Fence Calculator UK - Featheredge Boards, Rails & Posts

Close Board vs Panel Fencing

Panel fencing uses pre-made 1.83m sections slotted between fixed posts - fast to put up, but the posts must land at exact panel-width intervals, almost always leaving a cut panel somewhere along the run. Close board (featheredge) fencing is built on site, board by board, nailed to arris rails spanning between posts whose spacing can flex within a sensible range to divide the run into equal bays. It takes longer to install but gives a tidier finish on an awkward length, and it's the standard choice UK tradespeople reach for on a proper boundary fence.

Use panels for speed and lower cost on a straightforward level run. Use close board where the length doesn't divide evenly into panel widths, where the ground slopes, or where a longer-lasting, more repairable fence (individual boards can be replaced one at a time) matters more than installation speed.

How Many Featheredge Boards Per Metre?

This is the figure that gets quoted wrong more than almost anything else in fencing, because sources rarely say which board width they mean. The real relationship: boards per metre = 1,000 ÷ (board width - overlap). At a 25mm overlap: a 100mm board gives a 75mm exposed face and 13.3 boards per metre; a 125mm board gives a 100mm exposed face and exactly 10 per metre; a 150mm board gives an 80mm exposed face and 8 per metre. All three are correct answers - just to different questions. This calculator derives the figure from whatever board width and overlap you actually enter, rather than assuming one.

Arris Rails and Cant Rails

Two arris rails (a horizontal timber rail with a triangular cross-section) are standard for fences under 1.5m; three rails are standard at 1.5m and above, since a taller fence carries more wind load and needs the extra mid-height support. Rails run between posts, cut to the clear span of each bay - they're not sold at a fixed length the way panels are.

Cant rails are a heavier alternative: rather than a plain horizontal rail, the boards are angled slightly using a triangular cant strip, giving extra rigidity and a slightly overlapping, shingle-like look. More common on commercial installations or particularly exposed sites than standard domestic gardens.

Racking on Slopes: The Real Advantage Over Panels

A sloping garden is where close board genuinely earns its keep. Rails can be installed "racked" - parallel to the slope of the ground rather than level - with each board cut individually to a slight taper so the top edge follows the rise or fall smoothly. Panel fencing can't do this: a panel is a fixed rectangle, so on a slope it can only step down in whole-panel increments, leaving a visible staircase and awkward gaps underneath. If your garden isn't level, racked close board is usually the better-looking (if more labour-intensive) choice.

Post Centres and Why They Flex

Close board post spacing isn't fixed the way panel spacing is - it's chosen to divide your total run length into equal bays as close to a target spacing as possible, typically somewhere between 1.65m and 2.4m. A shorter target suits taller fences and exposed sites, since it keeps each rail span stiffer under wind load; a longer target is fine for lower, sheltered fences and uses fewer posts. This calculator finds the actual spacing that divides your run evenly within that range, rather than forcing a fixed figure and leaving an odd-width final bay.

Nailing: Ring Shank, and Never Through the Board Beneath

Use galvanised or stainless ring shank nails - the ridged shank grips the timber far better than a smooth nail and resists working loose as the boards move seasonally. Two nails per board per rail is standard, so a 3-rail fence needs 6 nails per board. Nail into the rail behind each board only - never drive a nail through the board and into the overlapping board beneath it. That pins the two boards together, and since timber moves independently as it dries and swells, a board nailed to its neighbour is a board that eventually splits along the nail line.

Close Board By Length: Quick Reference

100mm boards, 25mm overlap, 1.8m fence height, timber 100mm posts, 1.8m target centres, 5% waste - figures regenerated directly from the calculator above.

Use the calculator above for your own board width, overlap, post type and slope. Wickes and B&Q stock featheredge boards and arris rails for DIY-scale orders; Travis Perkins and specialist timber merchants suit trade quantities and can usually cut rails to length.

Frequently Asked Questions

How many featheredge boards per metre do I need?

It depends entirely on board width, which is exactly why a single "10 per metre" or "13 per metre" figure floating around online is meaningless without it. The real formula is 1000 / (board width - overlap): a 100mm board with a 25mm overlap gives a 75mm exposed face, or 13.3 boards per metre. A 125mm board at the same overlap gives a 100mm exposed face - exactly 10 per metre. A 150mm board gives 8 per metre. All three figures are correct; they're just answers to different questions.

What's the difference between close board and panel fencing?

Panel fencing uses pre-made 1.83m panels slotted between fixed posts - quick to install, but the posts must land at exact panel-width intervals, which usually means a cut panel at one end. Close board (also called featheredge fencing) is built on site from individual overlapping boards nailed to arris rails spanning between posts - slower to install, but the post spacing can flex to fit the run exactly, and it's the standard choice for a boundary fence that needs to look right on a slope or an awkward length.

How many arris rails does a close board fence need?

Two rails for fences under 1.5m, three rails at 1.5m and above - the extra rail is needed once board height (and therefore wind load) increases. Rails run between posts, cut to the clear span of each bay, not a fixed length. Cant rails (triangular-profile rails, used to angle boards for extra rigidity) are a heavier-duty alternative to plain arris rails, more common on commercial or high-wind installations.

Can close board fencing follow a sloping garden?

Yes, and it's the main practical reason many people choose it over panels. Close board can be "racked" - the rails installed parallel to the slope rather than stepped level bay to bay, with boards cut individually to a slight taper so the top edge follows the ground's rise or fall smoothly. Panels can only step in fixed increments, which looks noticeably worse on anything but level ground.

What nails should I use for featheredge boards?

Galvanised or stainless ring shank nails, 2 per board per rail - so 6 nails per board on a standard 3-rail fence. Ring shank nails grip far better than smooth ones and resist boards working loose as timber moves seasonally. Always nail into the rail, never through a board into the board behind it - that pins both boards together and stops them moving independently as they weather, which is what eventually splits them.

Why do close board post centres vary between 1.65m and 2.4m?

Because, unlike panels, close board isn't built from fixed-width pre-made sections - post spacing is chosen to divide the total run into equal bays as close to your target centres as possible, so there's never an awkward short bay at one end. A shorter target (around 1.65-1.8m) suits taller fences and exposed sites since it keeps rail spans shorter and stiffer; a longer target (up to 2.4m) is fine for lower, sheltered fences.