Colorbond fencing is the most popular boundary fencing choice in Melbourne — and for good reason. It's durable, low-maintenance, and available in a wide range of colours to suit any property. With the right preparation and materials, a competent DIYer or fencing contractor can install a clean, professional result that will last 30+ years.

This guide covers the full installation process from layout through to the finished fence.

What You'll Need

Posts:

• Steel SHS posts (50×50mm or 65×65mm) for standard Colorbond, or 100 UC H posts if you're adding a concrete plinth
• Post spacing: 2.4m centres for standard 2.4m Colorbond sheets

Base:

• Concrete plinth (optional but strongly recommended — see our guide on why your Colorbond fence needs a concrete plinth)
• Rapid-set concrete for post footings

Sheeting and fixings:

• Colorbond sheeting in your chosen colour and profile
• Colorbond top rail and bottom rail
• Colorbond screws and caps

Tools:

• Post-hole digger or auger
• String line and stakes
• Spirit level
• Drill and driver
• Tin snips or angle grinder with cutting disc
• Tape measure

Step 1: Check Regulations and Mark the Line

Before you dig a single hole, check your local council requirements. In Victoria:

• Fences on a boundary require neighbour notification under the Fences Act 1968
• Fences over 2m in height may require a planning permit
• Fences near easements or drainage reserves may have restrictions

Once you're clear on the rules, mark the fence line with a string line and stakes. Measure and mark each post position at 2.4m centres. Mark corner posts, end posts, and gate posts separately — these will need larger footings.

Step 2: Dig Post Holes

Post hole depth depends on fence height:

Fence Height	Minimum Post Depth
1.2m	450mm
1.5m	500mm
1.8m	600mm
2.1m	700mm

For corner and gate posts, add 100–150mm to these depths. The hole diameter should be approximately 3× the post width — so for a 65×65mm SHS post, dig a 200mm diameter hole.

Call Dial Before You Dig (1100) before any excavation to check for underground services.

Step 3: Set the Posts

This is the most critical step. Posts that are out of line or not plumb will make the rest of the job very difficult.

1. Set the two end posts first. Plumb them carefully with a spirit level and brace them in position.
2. Run a string line between the end posts at the top — this is your alignment guide for all intermediate posts.
3. Set each intermediate post to the string line, checking plumb in both directions.
4. Pour rapid-set concrete around each post. Keep the post braced until the concrete sets (typically 30–60 minutes for rapid-set).
5. Allow the concrete to cure for at least 24 hours before loading the posts with rails and sheeting.

Gate posts need larger, deeper footings and should be set in standard concrete (not rapid-set) for maximum strength. Allow 48–72 hours cure time before hanging gates.

Step 4: Install the Concrete Plinth (Recommended)

If you're using a concrete plinth — and we strongly recommend it — install it before the rails and sheeting.

The plinth slides into the post channels at the base of the fence, sitting on the ground. It keeps the Colorbond sheeting off the soil, preventing corrosion at the base of the panels and sealing the fence line against pests and water ingress.

FPM stocks plain and charcoal concrete plinths at 2360mm length to suit standard 2.4m post spacing. For uneven ground, plinths can be cut to length on-site.

Step 5: Install the Rails

Colorbond fencing uses a top rail and bottom rail system. The rails run horizontally between posts and the sheeting clips onto them.

1. Attach the bottom rail brackets to each post at the correct height (typically 50–75mm above the plinth or ground level)
2. Slide the bottom rail through the brackets along the full fence run
3. Attach the top rail brackets and install the top rail
4. Check that rails are level and at consistent heights along the run

For 1.8m fencing, a mid rail is recommended for additional rigidity, especially in exposed or windy locations.

Step 6: Install the Colorbond Sheeting

1. Start at one end post and work along the fence line
2. Slide the first sheet into position, engaging the ribs with the rails
3. Each subsequent sheet overlaps the previous one by one rib
4. Fix the sheets to the rails with Colorbond screws at the top, middle, and bottom of each sheet
5. Use a spirit level periodically to check the sheets are plumb

Cutting sheets: Use tin snips for small cuts or an angle grinder with a metal cutting disc for longer cuts. Always cut with the painted side up to avoid scratching. Deburr cut edges and apply touch-up paint to prevent rust.

Step 7: Install Gates

Gates are installed last. Standard Colorbond gates come as pre-hung units with hinges and a latch. Follow the manufacturer's installation instructions for your specific gate type.

Key points:

• Allow 10–15mm clearance between the gate and the post for smooth operation
• Adjust hinge positions to ensure the gate hangs level and swings freely
• Install a gate stop to prevent the gate swinging back against the fence

For double gates, install a drop bolt on the passive leaf to hold it in position when the gate is closed.

Step 8: Finish and Inspect

• Install post caps on all exposed post tops to prevent water ingress
• Apply touch-up paint to any scratched or cut edges
• Check all fixings are tight and all sheets are secure
• Clear the site of offcuts and debris

Common Mistakes to Avoid

Posts not plumb. Even a small lean compounds over a long fence run and makes sheeting installation very difficult. Take the time to get posts perfectly plumb.

Insufficient post depth. Shallow posts will move over time, especially in clay soils that expand and contract with moisture. Follow the depth guide above as a minimum.

No concrete plinth. Colorbond sheeting sitting on bare ground will corrode at the base within a few years. A concrete plinth is a small upfront cost that significantly extends fence life.

Wrong post type for gates. Standard SHS posts are not strong enough for heavy gates. Use 100 UC H posts for gate posts and set them deeper.

Materials from FPM Building Supplies

FPM stocks SHS posts, 100 UC H posts, concrete plinths (plain and charcoal), and rapid-set concrete from our Epping warehouse. We supply fencing contractors and homeowners across Melbourne and Victoria.

Use our free Colorbond fence estimator to calculate exactly how many posts, plinths and sheets your project requires. Or contact our team for trade pricing and project advice.