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How to Use Postcrete: The Complete Guide to Setting Fence Posts
Quick Answer
Postcrete (also written as ‘post crete’, and sometimes just called post mix) is a rapid-setting dry concrete mix designed specifically for fixing wooden, metal or concrete posts into the ground. Unlike traditional wet-mix concrete, there’s no mixing involved — you add water directly into the hole, pour the dry powder in around the post, and it typically sets in around 5 to 10 minutes. As a general starting point, plan for two bags per post, though larger or heavier posts may need more.
What is postcrete, and how does it work?
Postcrete is a pre-blended, rapid-setting dry-mix concrete, suitable for securing wood, metal and concrete posts. Because the cement is already blended with the right aggregates, there’s no need to mix it in a wheelbarrow or bucket first — you simply add water to the hole and tip the dry powder in around the post. Our own Post Mix range, including Premier Post Set, comes in a waterproof bag, requires no mixing, and is rapid setting in 5 to 10 minutes.
How many bags of postcrete do you need?
As a general rule, we recommend two bags of postcrete per post. The exact amount you need depends on the size of the post and the size of the hole — a hole roughly three times the width of the post, and around a third of the post’s overall length in depth, is the usual starting point for a standard garden fence post.
Post type | Typical guidance |
Standard timber fence post (garden fencing) | Around 2 bags per post |
Larger or heavier posts (entrance gates, exposed sites) | Allow extra — check hole size before you buy |
Topping up an under-filled hole | Buy at least one spare bag per fence run, so you’re not left short on the last post |
How to use postcrete: step by step
1. Check before you dig. Make sure you know where any pipes or cables run before digging — check with your local authority, or use a cable avoidance tool (CAT scanner) if you’re unsure.
2. Mark out and dig your holes. Lay a string line to mark the fence run, and space your holes to match your panel or bay width. A full third of the post’s overall height should sit below ground — most contractors allow around 600mm for a standard fence post.
3. Add drainage. Put roughly six inches of gravel in the base of the hole before positioning the post. Without it, the postcrete can form a ‘bucket’ around the base of the post with nowhere for water to drain — one of the most common causes of a post rotting prematurely.
4. Position the post. Stand the post in the hole. If you’re using an incised (pressure-treated) post, make sure the incised end goes into the ground — if you ever need to shorten a post, always cut from the top, never the incised end.
5. Add water, then postcrete. Pour water into the hole, then add the postcrete around the post until it reaches ground level.
6. Level and brace. Check the post is upright on two faces with a spirit level, and prop it with sturdy battens so it can’t move while the postcrete sets.
7. Leave it to set. Postcrete typically sets in 5 to 10 minutes, but avoid putting any strain on the post — such as attaching panels — until you’re confident it’s fully hardened.
8. Finish neatly. Smooth the top over and slope it slightly away from the post, so rainwater runs off rather than pooling around the base.
Postcrete vs traditional concrete
The main appeal of postcrete over a traditional wet-mix concrete is speed. Traditional concrete needs to be mixed with the correct ratio of aggregate and water, then left to cure for a day or two before it can safely take any weight. Postcrete is pre-blended, requires no mixing, and sets hard enough to hold a post upright within minutes — which is why it’s become the standard choice for fence, gate and deck post installations where you want to get on with the rest of the job the same day.
Common mistakes to avoid
Skipping the gravel drainage layer — this is the single biggest cause of posts rotting from the base up.
Not bracing the post while it sets — postcrete sets quickly, but a knock in the first few minutes can leave a post leaning.
Cutting the wrong end of an incised post — always shorten from the top, never the treated, incised end that goes into the ground.
Not checking for pipes or cables first — always check before digging any new post hole.
Under-buying — it’s worth having a spare bag on site so you’re not caught short on the last post of the run.
Which postcrete product should you choose?
We stock two options depending on what you need. Our Post Mix / Premier Post Set is rapid setting, supplied in a waterproof bag and needs no mixing. We also stock Post-mix Dry-mix 20kg K‑Rend, a rapid-setting post mortar suitable for wood, metal and concrete posts — just add water. Browse the full Post Mix & Postcrete range to compare bag options.
Postcrete near you
Walford Timber has been manufacturing and supplying timber and fencing products since 1945, with branches placed to serve customers across England and Wales:
Ross-on-Wye, Herefordshire — serving Hereford and the surrounding area
Cheltenham, Gloucestershire — serving Cheltenham, Gloucester and the surrounding area
Chesham, Buckinghamshire
Whichever branch is closest, you can collect postcrete in person or arrange delivery — get in touch with your local branch for current stock and delivery options.
FAQs
Is ‘post crete’ the same as postcrete?
Yes — postcrete and post crete are simply two ways of writing the same product name. It’s also sometimes called post mix or post-fixing mix.
How long does postcrete take to set?
Postcrete typically sets in around 5 to 10 minutes once water is added, which is why it’s so widely used for fence, gate and deck post installations.
How many bags of postcrete do I need per post?
As a general rule, plan for two bags per standard timber fence post. Larger, heavier posts, or posts going into bigger holes, may need more — it’s always worth having a spare bag on site.
Can postcrete be used for metal and concrete posts, not just timber?
Yes. Postcrete is suitable for securing wood, metal and concrete posts.
Do I need to mix postcrete before use?
No. Postcrete is designed so that you add water to the hole first, then pour the dry powder in around the post — there’s no need to pre-mix it in a separate container.
Where can I buy postcrete near me?
Walford Timber branches in Ross-on-Wye (Herefordshire), Cheltenham (Gloucestershire) and Chesham (Buckinghamshire) all stock postcrete for collection, with delivery also available — see our Post Mix & Postcrete range for current options.
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