Post and Rail Fencing: Materials, Spacing and Installation

Quick Answer: Standard 2 or 3-rail post-and-rail fencing uses 75×75mm or 100×100mm pressure-treated softwood posts at 1.83–3.0m centres, with 87×38mm rails morticed or nailed into face of post. Material cost runs £18–£35 per linear metre supply; total installed £43–£75 per linear metre. Used primarily for paddocks, boundary lines, and rural domestic settings under BS 1722-7.

Summary

Post-and-rail is the simplest fencing system — vertical posts joined by two or three horizontal rails, no panels or in-fill. It's the fence of choice for paddocks, large rural gardens, livestock containment, and boundary delineation where stock-proofing or privacy isn't required. Stock-proof versions add netting or barbed wire stretched on the rails.

The system has been used in the UK for centuries (the morticed cleft-rail version is medieval). Modern post-and-rail uses pressure-treated softwood, sometimes hardwood (oak, sweet chestnut) for premium or conservation settings. Installation is straightforward but post longevity depends on treatment grade and ground conditions — incorrectly treated softwood posts rot in 5–7 years in wet ground.

This article covers materials, post spacing, rail attachment methods, longevity expectations, and the difference between domestic-grade and equestrian-grade specifications. Equestrian fencing has higher impact-loading requirements and uses heavier sections.

Key Facts

Quick Reference Table

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Configuration Use Materials £/m Labour £/m Total £/m
2-rail 900mm boundary, softwood Garden/boundary £14–£22 £15–£25 £29–£47
3-rail 1.2m, softwood, 1.83m centres Domestic / pony paddock £18–£30 £18–£30 £36–£60
3-rail 1.4m, softwood, 2.4m centres Cattle / horse paddock £20–£32 £18–£28 £38–£60
4-rail 1.6m horse paddock, 1.83m centres Horse paddock £30–£45 £25–£40 £55–£85
3-rail + stock netting + barbed wire Sheep + cattle £26–£42 £25–£40 £51–£82
Oak post-and-rail 3-rail Conservation / heritage £55–£95 £30–£50 £85–£145
Sweet chestnut cleft post-and-rail Premium rural £65–£120 £35–£55 £100–£175
Post-and-wire (high-tensile 5-strand) Boundary / sheep £10–£18 £12–£22 £22–£40

Detailed Guidance

Post specification

Standard machined posts are 75×75mm or 100×100mm pressure-treated softwood, 1.8m or 2.4m long. For 900mm boundary use 1.8m posts (600mm in ground, 1.2m above + rail height). For 1.5m paddock use 2.4m posts (750–900mm in ground). For 1.8m horse fence use 3.0m posts (900mm in ground).

Treatment grade matters: UC4 (Use Class 4) for in-ground contact. Check the supplier's docs or the colour — properly UC4-treated timber is typically green-tinged (copper-based) or brown (creosote on agricultural). Untreated or undertreated posts will rot at the soil line within 5–7 years.

For premium and heritage work: oak posts are 100×100mm cleft or sawn, no treatment needed. Sweet chestnut similar. Both naturally durable (UC4 equivalent without preservatives). Cost is 4–6× pressure-treated softwood.

Strain posts (corners, gates, end of runs, every 50–80m on long straights) need stepping up — 150×150mm softwood or heavier hardwood. Always concreted in. Braced with diagonal stay from base back to fence direction.

Rail specification

Standard rail is 87×38mm machine-rounded ("half-rounded" or fully rounded). Length 3.6m most common (covers 2 bays at 1.83m centres with overlap on middle post). Lighter 75×38mm available for lower-impact applications. Heavier 100×50mm for heavy horse paddocks.

Rounded rails preferred for horse paddocks — fewer injury points if a horse panics into the fence. Square-edge rails fine for cattle, sheep, boundary, and domestic.

Hardwood rails (oak, sweet chestnut) £15–£30 per rail vs £5–£10 for softwood. Worth it for visible heritage settings.

Spacing and bay layout

Standard bay width is 1.83m post-to-post (6ft). Boundary-only fencing (visual demarcation, no stock pressure) can stretch to 2.4m (8ft) or even 3.0m (10ft) bays.

For paddock fencing, never exceed 2.4m post centres — rails sag and break under load. For horses, 1.83m is best practice — horses lean and rub posts, and longer spans flex more.

Strain post placement: corners (always), each side of a gate, end of run, and every 40–60m on straight long runs (50m for sheep wire, 80m for unwired rails).

Rail attachment — three options

  1. Morticed through post — Traditional and strongest. Posts pre-drilled or chiselled with through-hole; rail slotted through. Used on cleft chestnut and oak. Slowest to install but lasts longest.
  2. Nailed/screwed to face — Rails butt against post face, fastened with 100mm ring-shank nails (4 per join) or 100mm coach screws. Quickest. Most domestic post-and-rail.
  3. Mortice and tenon — Rail end tenoned to fit a post mortice but not through-pierced. Common on machined post-and-rail kits.

For domestic use, face-nailed is the standard. For paddocks with stock pressure, use 100mm galvanised screws or 100mm ring-shanked nails — smooth nails work loose under animal pressure.

Concrete or rammed?

Post-and-rail posts can be set in concrete or "rammed" (post in hole, surrounding earth/stone hard-packed). Rammed posts are quicker and cheaper, work fine in stable ground for boundary/sheep work. Concreted posts are stronger, last longer in wet/clay ground.

For UK domestic and paddock work: concrete posts as standard. Postcrete or wet mix both fine. For long agricultural runs (200m+ paddock), rammed may be acceptable on dry ground to control cost — agree with farmer before quoting.

Stock netting and barbed wire

Sheep netting (1m C8/80/15 standard) stapled to inside face of rails, 800mm or 1m high, plus 1 strand of plain or barbed wire stapled to top rail. Cattle: 2 strands barbed above netting.

Horse paddocks: NEVER barbed wire — use plain wire or no wire at all. Equine vets recommend electric tape rather than barbed; horses panic into barbed wire and cause severe injuries.

Highway-facing fences: Section 164 of Highways Act 1980 prohibits barbed wire that "is likely to be injurious to persons or animals lawfully using the highway." Council can require its removal. Use plain wire on roadside paddocks.

Gates within post-and-rail

Standard 3.6m field gate (galvanised tubular steel) hung on heavy gate posts (150×150mm minimum or 200×200mm oak). Hinges: top "hook-and-eye" (long hook 250mm), bottom "thrown over" or "U" hook. Heavy gates need adjustable hinges — galvanised drop-down hangers cost £30–£60 a pair.

Pedestrian gates (1.0–1.2m wide) on lighter 100×100mm posts. Self-closing spring hinge optional for stock-proof.

Always concrete gate posts at 900mm depth minimum. A 3.6m gate exerts huge leverage on its hinge post — under-spec post posts droop within months.

Installation sequence

  1. Mark out and dig all post holes (auger or shovel)
  2. Set end and corner (strain) posts first, concrete, brace
  3. Run a string line tight between strain posts
  4. Set intermediate posts to string line, concrete or ram
  5. Allow concrete to set (overnight for wet mix, 15 min for Postcrete)
  6. Fix top rail first along full run (height datum)
  7. Fix middle and bottom rails to top-rail datum
  8. Stretch netting and wire (if used) from corner strain
  9. Strain posts: install diagonal stays

For a 100m straight fence with 3 rails and 2-fitter team: 1.5–2 days including setting out.

Frequently Asked Questions

How long does post-and-rail fencing last?

Pressure-treated UC4 softwood: posts 12–18 years, rails 20–25 years (because rails aren't in ground contact). Oak or sweet chestnut: 30–60 years untreated. Painted/stained softwood: similar to treated softwood but with cosmetic refresh every 5 years. Failure is almost always at the soil line on posts — concrete-filled or properly drained posts last longest.

Can I use post-and-rail to keep livestock in?

Plain 3-rail won't contain sheep or piglets — they squeeze under. Add stock netting (sheep) or 6-bar gates and rails (cattle). For horses, 3-rail with rails at correct heights (top rail 1.2–1.4m, middle 75cm, bottom 30cm) is standard; horses respect the visual barrier even though it's physically modest. Never use barbed wire with horses.

What's the difference between cleft chestnut and machine-rounded rails?

Cleft sweet chestnut is split along the grain (axe or wedge), follows natural fibre lines, very durable, traditional look. Machine-rounded is sawn then rotated through a cutter to a uniform round profile, faster to produce, uniform appearance. Cleft costs 2–3× machined; lasts longer; preferred in conservation areas and high-end estates.

Do I need planning permission for post-and-rail?

Under Permitted Development Order 2015: fences up to 2.0m in rear gardens / 1.0m abutting highway are PD. Most domestic post-and-rail is below these limits. Agricultural fencing on land used for agriculture is generally exempt under different PD provisions, but check with the council if uncertain — Article 4 Directions can vary.

How do I stop posts rotting at the ground line?

Three things: use UC4 treatment grade (not UC3 or "garden grade"), avoid encasing the post bottom in concrete (set on gravel pad or leave drained), slope the concrete top above ground so water sheds away. Encased post bottoms hold water against timber and accelerate rot. A 75×75mm UC4 post set on gravel with sloped concrete collar lasts 18–25 years.

Regulations & Standards