Post and Rail Fencing: Materials, Spacing and Installation

Quick Answer: Standard UK three-rail post-and-rail fencing uses 100×100mm UC4-treated softwood posts at 1.83m centres, with 87×38mm rails morticed into the posts. For agricultural use, BS 1722-7 specifies a minimum post depth of 600mm in firm ground; for boundary use, increase to 750–900mm. Materials cost £25–£40 per linear metre, supply-and-fit £45–£70 per linear metre in 2026.

Summary

Post-and-rail fencing is the workhorse of UK rural and equestrian boundaries — durable, repairable, and cheap per metre compared to closeboard. The classic three-rail design is the long-standing standard for paddocks, farms, and large rural boundaries; the four-rail variant is used where stock containment is critical (horses, sheep, cattle); the two-rail variant suits decorative boundaries on long driveways or estate frontages.

In 2026, prices for tanalised softwood posts have softened slightly with stable timber supply, but rail prices have climbed 8–12% as preservative chemistry tightens under HSE rules and BS 8417 use-class 4 specification has become the industry default for ground-contact components. The single biggest pricing variable is post depth and ground type — soft rural ground often needs 750–900mm posts where 600mm would do in firm clay, and that adds 8–15% to materials cost.

Key Facts

• Standard post size — 100×100mm UC4 treated for in-ground; 100×75mm acceptable for short-run decorative
• Standard rail size — 87×38mm sawn softwood UC3-treated; 100×38mm for heavy stock
• Standard post centres — 1,830mm (6ft) — matches stock 1.83m rail length minus 5mm tolerance
• Three-rail spacing — bottom rail 200mm above ground, top rail 100mm below post top, middle rail centred
• Four-rail spacing — equally divided across post height; for 1.4m post, rails at 250mm/550mm/850mm/1,150mm above ground
• Post depth — 600mm in firm soil per BS 1722-7; 750mm clay/loam; 900mm sandy/peat
• Treatment — UC4 BS 8417 for posts, UC3 BS 8417 for rails
• Common heights — 1.0m, 1.2m, 1.4m above ground (excluding post depth)
• Rail jointing — morticed (high-spec, longest life) or nailed (cheaper, shorter life)
• Throughput — single-handed fencer 25–35m per day in good ground, 18–25m per day with extraction
• Lifespan — 15–25 years for UC4 softwood with proper installation; 30+ years for hardwood (oak, chestnut)
• Wire mesh addition — netting (50×50mm or 75×75mm aperture) typically £4–£7 per linear metre for materials

Quick Reference Table — Post and Rail Specification

UC4 BS 8417 ground-contact treatment for posts, UC3 for rails. Hardwood (oak or sweet chestnut) requires no treatment but commands a 50–80% premium on cost.

Detailed Guidance

Materials

Posts. Standard UK rural fence post is 100×100mm sawn softwood treated to BS 8417 use class 4. Post lengths of 1.65m, 1.95m and 2.4m cover the common above-ground heights of 1.0m, 1.2m and 1.4m respectively. Hardwood (sweet chestnut, oak) is the long-life specification — 30+ years vs 15–25 years for treated softwood — and adds 50–80% to material cost.

Rails. 87×38mm is the industry standard for three-rail and four-rail. For heavy stock (cattle, large horses), step up to 100×38mm or 125×38mm. Length is 1.83m (6ft) to suit standard 1.83m post centres. Morticed rails (cut at the ends to slot into pre-cut holes in the post) are the high-spec choice; nailed rails are quicker and cheaper but rely on the nails alone for shear resistance.

Fixings. Morticed rails are typically secured with a 100mm × 4.5mm galvanised round-head nail driven through the post into the rail tenon. Nailed rails use 90mm × 3.75mm galvanised round-head nails — two per rail per post, offset to avoid splitting. For long-life fences, A2 stainless steel ring shanks reduce loosening over time.

Post setting

Three setting methods:

1. Postcrete — single 25kg bag per post, 5–10 minute set. Most common for small to medium runs. Quick to install but harder to remove if a post snaps later.
2. 1:6 ballast and cement — slower set (24–48 hours) but bonds well. Better for long-run installations where speed isn't critical.
3. Compacted hardcore — no cement at all. Common for chestnut paling and short-life agricultural fencing. Posts can be re-driven if loose.

For boundary post-and-rail (as opposed to internal-stock fencing), postcrete or concrete is the standard. Hardcore-only setting is acceptable for paddocks and internal field divisions where post replacement is expected over the life of the fence.

Rail jointing — morticed vs nailed

Morticed jointing is BS 1722-7's preferred method. The post has a rectangular through-mortice cut into it (approximately 90×40mm); the rail end is shaped to match (a haunched tenon), passes through the post, and locks against the next post on the far side. The result is a continuous run of rails with no fasteners visible.

Nailed jointing relies on the nail to take the shear load when an animal pushes against the rail. It works for light stock but lasts less time — the nail loosens, the rail splits, the joint fails. For paddock or stock-containment fencing, always specify morticed.

Wire mesh additions

Adding livestock netting to a post-and-rail fence is common where stock containment is critical:

• Sheep netting (50×50mm aperture) — £4–£7 per linear m supply
• Stock fence netting (75×100mm aperture, graduated) — £3–£5 per linear m supply
• Rabbit-proof netting (25×25mm or 31×31mm aperture) — £5–£9 per linear m supply, with 150mm buried at base
• High-tensile sheep netting — £6–£10 per linear m for higher specification

Mesh is fixed to the rail face with 25mm galvanised staples at 200mm centres along the top rail and 300mm centres along the others.

Hardwood post-and-rail — when to recommend

Sweet chestnut and English oak post-and-rail is the long-life specification. Lifespan is 30+ years vs 15–25 years for UC4 softwood. The premium is 50–80% on materials but most of that is recovered through reduced maintenance and replacement over the life of the fence. Best suited to:

• Estate or country park boundaries where aesthetic and longevity both matter
• Listed Building or Conservation Area where untreated traditional materials are preferred
• Long boundary runs where access for future repair is difficult

Sweet chestnut is the higher-spec choice — naturally durable to BS EN 350 class 1, highly resistant to fungal attack, and historically the British rural fencing material before tanalised softwood became standard. Oak posts in chestnut rails is a common combination that gives the best price/performance balance.

Throughput pricing — solo vs two-man crew

A solo fencer with mechanical post-driver in firm ground: 25–35m per day. With manual driving (lump hammer + post-driver tube): 18–25m per day. Add 5–10m per day extraction allowance if old fence is being removed. A two-man crew with mechanical driver: 45–65m per day in good ground. Use these figures for scheduling, but always price by linear metre, not by day — the day-rate model encourages slow installation.

Frequently Asked Questions

Should I use posts or stakes for paddock fencing?

Posts. "Stakes" (round, treated, 75–100mm diameter) are sometimes used in agricultural fencing where flexibility is important (livestock wire, electric fencing) but for post-and-rail you need square or rectangular posts so you can mortice the rails into them. Round stakes don't take a clean mortice.

How much does post-and-rail fencing cost per metre on a UK paddock (homeowner-friendly)?

For a typical UK paddock with three-rail fencing at 1.2m height, materials cost £25–£40 per linear metre. Supply-and-fit by a fencer is £45–£70 per linear metre. A 200m paddock fence costs £9,000–£14,000 supply-and-fit — typical ballpark for the equestrian market. Hardwood (oak/chestnut) doubles the price to £18,000–£24,000 for the same run. Always include the labour for striking out the old fence (typically £8–£15 per linear metre) if applicable.

Can post-and-rail be used as a security fence?

No. Post-and-rail is a livestock containment and visual boundary fence. It provides no security against trespass — a person can climb over a 1.2m fence in seconds. For security, use close-board fencing at 1.8m, metal palisade or anti-climb topping. Combination fencing (post-and-rail + welded mesh + barbed wire topper) is sometimes used on agricultural perimeters but won't deter determined intruders.

What height for a horse paddock?

1.2m is the minimum for a paddock. 1.4m is recommended for thoroughbreds and other tall breeds. Top rail must be at horse-shoulder height to prevent the animal pushing through. Three-rail spacing is standard but four-rail is recommended where foals may be present (to prevent rolling under the bottom rail). For competition or stallion paddocks, 1.5–1.8m four-rail with mesh infill is the higher specification.

What's the best post-setting method on wet or peat ground?

Compacted hardcore (no concrete) is the traditional approach on wet or peat ground. Concrete in saturated peat can sit in a "wet sock" that doesn't bond, and post movement results. Drive the post deeper (900mm minimum), backfill with compacted angular ballast in 100mm lifts, and tamper between layers. For boundary post-and-rail (as opposed to internal field fencing), consider raising the fence on a stone-filled mound rather than relying on post depth alone.

Regulations & Standards

• BS 1722-7 — wooden post-and-rail fences specification

• BS 8417 — preservation of wood — code of practice (use class 4 for ground contact)

• GPDO 2015 Schedule 2 Part 2 Class A — permitted development for fences/walls

• Wildlife and Countryside Act 1981 — protected species considerations during clearance

• Highways Act 1980 Section 154 — fence and hedge maintenance adjacent to public highways

• Animal Welfare Act 2006 — fencing standards for livestock containment (general duty of care)

• BS EN 350 — natural durability of solid wood (for hardwood specification)

• BSI — BS 1722-7 wooden post-and-rail fences

• Planning Portal — fences and walls permitted development

• HSE — Working at Height Regulations 2005

• GOV.UK — boundary feature responsibility

• BSI — BS 8417 wood preservation code of practice

• timber closeboard fencing — boundary specification when post-and-rail is too open

• concrete posts and gravel boards — alternative boundary specification

• chestnut paling temporary and rustic fencing — short-life agricultural variant

• fencing installation pricing — quoting framework for all fence types