Aluminium Gates Poles – Concrete InstallationInstalling poles for aluminium gates — including SecOnline gates designed to suit 40 × 40mm square aluminium posts — is a simple job, but ground condition is one of the most important factors to consider and is frequently overlooked
Different soil types behave very differently once you introduce moisture, weight and movement. Choosing the right concrete approach for your conditions can make the difference between posts that stay perfectly plumb for years, and posts that slowly lean, sink or loosen over time.
Here are a few key things you should know about ground conditions before installing your posts.
Why Ground Conditions Matter
Your pole footing has one job: to resist movement. That movement can come from:
Expansive soils that swell when wet
Loose or sandy ground that won’t compact
Clay that holds water
Sloped sites where gravity is constantly pulling on the poles
Wind loads on gates or tall panels
Common Ground Types (and How to Work With Them)
Sandy or Loose Soil
Characteristics
Drains quickly
Doesn’t compact well
Can collapse back into the hole
Offers minimal natural support
Best approach
Use a larger hole diameter than usual
Bell out the base of the hole if possible (wider at the bottom)
Use a standard structural concrete mix
Tamp soil firmly around the outside of the concrete once poured
Pro tip: In very loose sand, adding a small gravel base before placing the post can improve stability.
Clay Soil
Characteristics
Holds water
Expands and contracts with moisture changes
Can push posts upward over time
Common in many Australian backyards
Best approach
Ensure good drainage at the base (add crushed rock before concreting)
Avoid shallow, straight-sided holes
Go deeper than usual to get below the most reactive zon
Use a normal concrete mix and allow proper curing time
Pro tip: Never leave standing water in clay holes before pouring — bail it out first.
Rocky or Hard Ground
Characteristics
Excellent natural stability
Difficult to dig
Limited hole diameter
Best approach
Drill or jackhammer where needed
Use higher-strength concrete if hole size is restricted
Make sure the pole is well centred
Fill all voids completely with concrete
Because rock already provides strong lateral support, depth is often more important than width here.
Mixed or Fill Ground
Characteristics
Often found in newer estates
Inconsistent layers
May contain builder’s rubble
Settles over time
Best approach
Dig until you reach undisturbed soil where possible
Increase footing depth
Compact surrounding material carefully
Consider slightly stronger concrete
Fill ground is unpredictable, so deeper footings usually pay off
Choosing Your Concrete Type
For most DIY pole installations, you’ll be choosing between:
Standard Premix Concrete
Best for:
Most fence posts
Gates
Stable soil conditions
Requires mixing with water before pouring.
Rapid-Set / Post Mix
Best for:
Quick installs
Smaller posts
Jobs where speed matters
Usually poured dry into the hole, then watered. Convenient, but not always ideal for larger or heavily loaded posts.
Higher-Strength Concrete
Best for:
Heavy Gates
Tall structures
Soft or unstable soil
Narrow holes
Offers extra rigidity where ground support is limited.
Don’t Forget Alignment and Bracing
Before your concrete sets:
Check posts are plumb on two sides and will set at the required height
Allow full cure time before hanging gates or applying load
Rushing this step is one of the most common causes of leaning posts.
Final Thoughts
Good installations start below ground. Matching your footing method to your soil conditions gives your poles the best chance of staying straight, solid and reliable for years to come — especially for gates and other moving components.
Important! the information above is general advice only and doesn’t account for your specific site conditions, loads, or local requirements, so specialised guidance may be needed for your project
Aluminium Gates Poles – Concrete Installation