Our Guide to Working With Post Mix

Post Mix is a versatile concrete product, useful for different DIY and industrial applications. Concrete provides strong foundations for your gate and fence posts, as well as the base of paving and pathways.

AVS Postmix – £6.99 Per Bag

What is Post Mix produced from?

Post Mix is a concrete, made from a mixture of cement and ballast with water added. Post Mix is also referred to as postcrete and is specifically designed for setting timber, concrete or metal fence posts. This ready mixed concrete is however also ideal for smaller jobs around the garden as it effectively sets objects in place.

What are the benefits of using ready made concrete?

Post Mix saves time and effort as the quality mixture is already made up and ready to use. You will also end up saving a few pennies as you are less likely to accumulate more concrete than you actually need.

Finally, Post Mix eliminates the issue of finding space to store large quantities of concrete. Instead Post Mix is available in conveniently sized bags, ready to get going whenever you are!

So, how do you use Post Mix?


  • First, Post Mix Concrete can work for setting any kind of fence posts: metal, concrete or wooden. It provides a solid base for all of these posts and any kind of fencing, such as fence panels, closeboard or palisade styles. Post Mix sets very quickly, so you can construct more fencing in one day, as well as get other work done.
  • With Post Mix concrete there’s no premixing, as with cement and ballast: more time saved. The same initial steps apply before use of Post Mix Concrete. That is, dig your fence post hole (at least 600mm deep); width will depend on the size of the post being erected. Using a post hole digger will help in softer earth, for smaller posts. Larger holes might need an auger or shovel first. If installing in an area where drainage of water is slow or absent, add shingle beneath the post to help drain away moisture.
  • Also, aggregate mixes are not suggested for placement below posts. Water held in them could cause early rotting from post absorption. Next, place your post and check vertical alignment with a spirit level, on both front and side faces. (Sometimes, posts are held secure with wooden braces to assure vertical alignment.) Complete instructions are printed on each 20kg bag of Post Mix Concrete to make it easy, but here are the simple steps to follow.




  • Pour half a bag of Post Mix Concrete into the hole – using more for larger holes and posts. Using a watering can with a fine rose, pour clean water around the post’s base, at the mix’s level. After just two minutes – don’t walk away, this is fast-setting material! – check vertical alignment with the spirit level. Adjust post positioning as needed. Repeat this process, directing water onto the post at ground level. Setting takes only 15-20 minutes, before further work can commence. Quick!


You’ll need about 1 & 1/3rd bags of Post Mix Concrete for each hole for 75 x 75mm and 100 x 100mm fence posts. That’s about 11 bags of postfix for eight fence panels. Gate Posts, which take a bit more strain from gate movement, might use three to four bags.


  • The posts should be buried from 600mm (2ft) to 750mm (2ft6″) into the ground, depending on the height of the fence; the postfix is to be placed around the post, but not underneath. If a post has the concrete underneath as well as around the sides the concrete can trap water and therefore soak the post, greatly increasing the chance of decay.
  • If the ground the post is sunk into is not free draining soil then a small layer of shingle can be placed under the fence post, (with the post still sunk a minimum 600mm into the ground), to help drainage occur.

So, there we have it – our top tips on using Post Mix concrete. Just let us know how you get on with this handy product in the comment box below!


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21 Feb 18