What is the standard spacing for post and rail fencing?

In the UK, the standard spacing for posts is 1.8 metres (6ft). This allows for 3.6m rails to span across three posts (starting at post 1, supported by post 2, and ending at post 3). Some agricultural installations use 2.1m or even 2.4m spacing, but this is less robust.

How many rails do I need for a horse paddock?

For horses, a 3-rail or 4-rail fence is the industry standard. This ensures the fence is visible to the animals and provides enough of a physical barrier to prevent them from leaning over or crawling under.

What does 'UC4 treated' timber mean?

Use Class 4 (UC4) is a treatment standard for timber that will be in constant contact with the ground. It involves a more intensive pressure-treatment process to ensure the timber does not rot. Always ensure your fence posts are UC4 rated.

Should I nail the rails to the front or back of the posts?

For agricultural and equestrian use, rails should always be nailed to the 'inside' (the animal side) of the posts. This way, if an animal leans or runs into the fence, they push the rail into the post rather than popping the nails out.

What is the standard spacing for post and rail fencing?

In the UK, the standard spacing for posts is 1.8 metres (6ft). This allows for 3.6m rails to span across three posts (starting at post 1, supported by post 2, and ending at post 3). Some agricultural installations use 2.1m or even 2.4m spacing, but this is less robust.

How many rails do I need for a horse paddock?

For horses, a 3-rail or 4-rail fence is the industry standard. This ensures the fence is visible to the animals and provides enough of a physical barrier to prevent them from leaning over or crawling under.

What does 'UC4 treated' timber mean?

Use Class 4 (UC4) is a treatment standard for timber that will be in constant contact with the ground. It involves a more intensive pressure-treatment process to ensure the timber does not rot. Always ensure your fence posts are UC4 rated.

Should I nail the rails to the front or back of the posts?

For agricultural and equestrian use, rails should always be nailed to the 'inside' (the animal side) of the posts. This way, if an animal leans or runs into the fence, they push the rail into the post rather than popping the nails out.

Post & Rail Calculator

Fast material takeoff for open timber fencing.

Total Fence Length (m)

Number of Rails

Post Spacing (m)

Rail Timber Length (m)

Material Estimate

Professional Tip: For agricultural use, ensure posts are **UC4 treated** (intended for ground contact). For horses, a 3 or 4-rail fence is recommended for safety and visibility.

Post & Rail: The Timeless Country Boundary

Open & Aesthetic

Post and rail fencing is the preferred choice for large perimeters where privacy is not a concern. It maintains an open, airy feel while providing a clear physical boundary for livestock, pets, or property lines.

Our **post and rail calculator** estimates materials for standard UK timber sizes, ensuring you have the right number of 3.6m (12ft) rails for your specific run length.

Material Standards

Standard Rail38mm x 87mm x 3.6m

Standard Post75mm x 125mm

Post Centres1.8m (Recommended)

Professional Installation Techniques

To ensure a post and rail fence remains straight and strong, you should **stagger the rail joints**. For example, in a 3-rail fence, join the top and bottom rails on Post A, and join the middle rail on Post B. This prevents a single post from carrying all the joint stress and creates a significantly more rigid structure.

For the rails, use 100mm (4-inch) galvanised nails. Each rail should have at least two nails per post to prevent 'twisting' as the timber dries out in the sun.

Square vs Round Posts

Square-sawn posts are easier to nail to and provide a cleaner look for domestic gardens. Round or half-round posts are traditional for agricultural land and are often slightly cheaper.

Capping Your Posts

The most common point of failure in a post and rail fence is the top of the post where water sits. Cutting the top of the post at a slight angle (a weather cut) helps water run off, preventing premature rot.

Pro Tip: Morticed Posts

For a truly premium finish, consider **morticed post and rail**. The rails are tapered at the ends and slot into pre-cut holes (mortices) in the centre of the posts. This requires no nails and looks spectacular, though it is more expensive and harder to install.

Agricultural Fencing FAQ

Paddock Disclaimer

While post and rail is excellent for horses, always ensure there are no sharp edges or protruding nails. For very small animals or those prone to escaping, you may need to add a layer of stock netting (wire mesh) to the bottom half of the fence.