When it comes to setting fence posts, securing gate posts, or any number of outdoor building projects, one of the initial—and most crucial—choices you'll face is selecting the right material to secure your installation. Two of the most popular options are traditional sand and cement mixes and the more modern, ready-to-use postmix. Each comes with its own set of benefits and considerations. In this comprehensive guide, we'll explore the differences between sand and cement mixes and postmix, helping you make an informed decision for your project.

Understanding Sand and Cement Mixes

Traditionally, a mix of sand and cement is used for setting posts. This method involves blending sand, cement, and water on-site to create a mortar, which is then used to bed in the posts.


  1. Flexibility in Mixing: Allows for the adjustment of the mix ratio based on the specific needs of the project, such as varying the mix for softer or more rocky ground.
  2. Cost-Effectiveness: Generally cheaper than pre-mixed solutions, especially for larger projects where materials can be bought in bulk.
  3. Availability: Materials for sand and cement mixes are readily available and can be used for a variety of other construction needs.


  • Time and Labour Intensive: Requires the correct ratio of sand to cement and thorough mixing to achieve the desired consistency.
  • Skill Level: Achieving the right mix can be challenging for DIYers without prior experience.
  • Weather Conditions: Wet or humid weather can affect the mix and setting time.

Postmix: The Modern Alternative

Postmix is a pre-mixed, ready-to-use formula designed specifically for setting posts. It usually consists of a dry mixture of cement and aggregate, to which you simply add water.


  1. Convenience: Pre-mixed and easy to use straight out of the bag, saving on preparation time.
  2. Quick Setting: Sets posts within 5 to 10 minutes, allowing for faster completion of projects.
  3. No Waste: Use only what you need for each post, reducing waste.


  • Cost: Typically more expensive per post than mixing your own sand and cement.
  • Less Flexibility: Does not allow for adjusting the mix based on specific project needs or ground conditions.
  • Shelf Life: Once opened, any unused postmix can potentially absorb moisture and become unusable if not stored correctly.

Which to Choose for Your Project?

The choice between sand and cement vs postmix comes down to a few key factors: the scale of your project, convenience, cost, and your level of experience.

  • Scale of Project: For large projects or where materials are already on hand, sand and cement might be more economical. For smaller projects or where ease and speed are priorities, postmix offers a convenient solution.
  • Convenience: If you prefer a quick, clean, and straightforward process, postmix is undoubtedly the way to go. If you don't mind the extra labour and have the skills to mix your own, sand and cement offer more control over the project.
  • Cost: Budgetary constraints may influence your choice. Although sand and cement might be cheaper, consider the value of your time and the potential for material waste.
  • Experience: For beginners, postmix presents a foolproof option that minimises the chance of incorrect mixing ratios and ensures a strong set.


Both sand and cement mixes and postmix serve their purposes well, offering different advantages based on the needs of the project and the preferences of the builder. While the traditional sand and cement approach allows for a customised mix and might save on costs for larger projects, postmix offers an unbeatable combination of convenience, speed, and ease of use, making it ideal for quick repairs and small-scale installations.

Ultimately, your choice will depend on balancing these considerations against the specifics of your project. Whether you opt for the tried-and-tested route of sand and cement or the convenience of modern postmix, understanding the properties and potential of both options is your first step towards a successful outdoor construction project.