Postmix is the rapid setting pre-mixed concrete supplied by us. Supplied in 20kg showerproof sacks for fixing concrete, metal or wooden fence posts, gate posts and railings.

We always keep these products in stock so you can save time and money by picking up a few bags with your fencing materials.

Why use rapid setting concrete?

Most fence and gate posts need to be secured into holes by using concrete. Traditionally fence erectors have had two options:

  1. Mix sand and cement on-site
  2. Get a supplier to deliver ready mixed concrete

Postmix has lots of benefits over these traditional options: 

  • Supplied in 20Kg strong shower proof non-slip bags
  • No waste of time on site either going to collect ready-mix from a local depot or waiting for a delivery to arrive
  • No waste of concrete, even if you get a bit more 'just-in-case' what you do not need, you can use on the next job
  • Ready to use, no mixing required on site, a correct mix every time making sure the posts are secure
  • Postmix sets in 5-10 minutes and fully hard within hours

We have calculated the volume of postmix for differing post sizes and hole depths.  You can buy as much as you need to use or to stock.

Hole width
Hole depth for a 75 x 75 square post
450mm
600mm
750mm
150mm ½ bag ½ bag ¾ bag
200mm ¾ bag 1 bag 1¼bags
Hole width
Hole depth for a 100 x 100 square post
450mm
600mm
750mm
200mm ¾ bag 1 bag 1¼ bag
250mm 1 bag 1½ bags 2 bags
Hole width
Hole depth for a 150 x 150 square post
600mm
750mm
1000mm
250mm 1 bag 1½ bag 2½bags
300mm 2 bags 2½ bags 4 bags
Hole width
Hole depth for a 175 x 175 square post
600mm
750mm
1000mm
300mm 1½ bags 2 bags 3 bags
350mm 2¾ bags 3½ bags 4½bags
Hole width
Hole depth for a 200 x 200 square post
600mm
750mm
1000mm
300mm 1½ bag 1¾ bags 2½ bags
350mm 2½ bags 3 bags 4 bags