How to Install Gate Posts for Wooden Field Gates

Installing gate posts correctly is essential to ensure your wooden field gate remains secure, level, and fully functional for years to come. Whether you are installing an entrance gate to a paddock, driveway, or garden, the strength of the installation depends almost entirely on the quality of the gate posts and how they are set into the ground.

Across Suffolk, Essex, Norfolk, and Cambridgeshire, we regularly supply gate posts and field gates for agricultural access, rural properties, and residential driveways. This guide explains how to install gate posts properly using Postmix, along with recommended products and best practices.

Choosing the Correct Gate Posts

Field gates are heavy and create constant leverage on the hinge post. Using undersized posts or installing them incorrectly will lead to sagging, misalignment, and premature failure.

For most standard wooden field gates, we recommend the following softwood UC4 pressure-treated gate posts:

The 150mm posts are suitable for standard garden and light agricultural gates, while 200mm posts are recommended for larger, heavier field gates or exposed locations.

UC4 pressure treatment ensures maximum durability in ground contact, protecting the timber from rot and fungal decay. This makes them ideal for long-term installation across rural environments in East Anglia.

Oak gate posts are also available as a premium alternative, offering exceptional strength, natural durability, and a traditional appearance.

Recommended Supporting Products

To ensure a strong, long-lasting installation, we recommend using the following supporting products:

Postmix concrete for securing the posts
Post saver sleeves to extend the life of the timber
Field gate ironmongery including hinge sets and latches
Matching wooden field gates

Using the correct installation materials significantly improves longevity and prevents movement over time.

Post saver sleeves provide an additional protective barrier around the most vulnerable section of the post, preventing moisture and ground contact from causing rot. This can more than double the lifespan of timber gate posts.

How Deep Should Gate Posts Be Installed?

For field gates, gate posts must be installed much deeper than standard fence posts due to the weight and leverage forces applied.

We recommend:

Minimum hole depth: 600mm
Hole diameter: approximately 100-150mm wider than your post diameter
Post height above ground: approximately 1.8m from a 2.4m post

This burial depth provides sufficient anchoring strength to support the weight and movement of field gates.

In softer ground or for larger gates, installing slightly deeper will provide even greater stability.

How Much Postmix Do You Need to Install a Gate Post?

Gate posts require significantly more concrete than standard fence posts.

Recommended amount:

3 to 5 bags of Postmix per gate post
Heavier gates and 200mm posts typically require 4 to 5 bags
Lighter gates with 150mm posts typically require 3 to 4 bags

Postmix is fast setting and provides excellent structural support. It is the preferred installation method across agricultural and residential gate installations throughout Suffolk and surrounding counties.

Step-by-Step Gate Post Installation Guide

Step 1: Mark the Gate Opening

Measure the exact width of your field gate and mark the locations of both posts. Allow a small clearance gap on the hinge and latch sides to ensure smooth operation.

Ensure both posts will be perfectly aligned.

Step 2: Dig the Post Holes

Dig holes:

Minimum 600mm deep
300mm to 400mm diameter

Ensure the bottom of the hole is firm and level.

This depth is essential to properly support the weight of field gates.

Step 3: Install Post Saver Sleeves

Slide post saver sleeves onto the bottom section of the gate posts before installation.

These sleeves protect the timber at ground level, which is where most rot occurs.

This significantly extends the life of the gate posts, particularly in wet ground conditions common across East Anglia.

Step 4: Position the Gate Posts

Place the first gate post into the hole and ensure it is perfectly vertical using a spirit level.

Check alignment carefully, as this post will carry the hinge load.

Temporarily brace the post to hold it in position.

Step 5: Add Postmix

Pour Postmix evenly around the post inside the hole.

Follow the instructions on the Postmix packaging and add water as required.

Use:

3 to 5 bags per post depending on size and conditions

Allow the concrete to fully set before attaching the gate.

Step 6: Install the Second Post

Repeat the same process for the latch post.

Ensure both posts are aligned and level with each other.

Correct spacing is critical for proper gate operation.

Step 7: Attach Field Gate Ironmongery and Hang the Gate

Once the posts have fully set, install your field gate ironmongery including hinges, latch, and fittings.

Attach the hinges securely to the hinge post and hang the gate.

Make final adjustments to ensure smooth opening and closing.

Why Proper Gate Post Installation Matters

Correct installation provides:

Long-term structural stability
Prevents gate sagging and misalignment
Improves safety and security
Extends the lifespan of both gate and posts
Reduces maintenance requirements

Properly installed UC4 gate posts using Postmix and post saver sleeves can last decades.

Local Supply Across Suffolk, Essex, Norfolk and Cambridgeshire

Clarke Fencing supplies gate posts, Postmix, ironmongery, and field gates across East Anglia. Whether you are installing a garden gate, driveway entrance, or agricultural field gate, we provide high-quality materials suitable for long-term outdoor use.

Our UC4 pressure-treated gate posts and installation products are trusted by homeowners, landscapers, and agricultural customers throughout the region.

Summary

To install gate posts correctly:

Use 150mm or 200mm UC4 pressure-treated gate posts
Dig holes minimum 600mm deep
Use 3 to 5 bags of Postmix per post
Install post saver sleeves for extended lifespan
Ensure posts are level and aligned
Install proper field gate ironmongery

Following these steps ensures your gate installation remains secure, level, and durable for many years.

Jason Clarke

Ask them a question by emailing [email protected]

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