A Colorbond gate completes a Colorbond fence and adds security and convenience to any property. Whether you're installing a pedestrian gate or a double driveway gate, the process is the same — it's all about getting the posts right.

This guide covers everything from selecting the right gate posts through to final adjustment.

What You'll Need

Materials:

• Colorbond gate (pre-made or site-fabricated)
• Gate posts — C posts or square hollow section (SHS) steel
• Concrete (N20 minimum)
• Gate hinges — heavy-duty weld-on or bolt-on type
• Gate latch or lock
• Gate drop bolt (for double gates)
• Post caps

Tools:

• Post-hole digger or auger
• Spirit level
• String line
• Tape measure
• Drill and bits
• Spanner set
• Angle grinder (if cutting posts)

Step 1: Choose the Right Gate Posts

Gate posts carry significantly more load than standard fence posts — they support the weight of the gate and the dynamic forces of opening and closing. Undersized gate posts are the most common cause of sagging gates.

For pedestrian gates (up to 1.0m wide):

• 65×65mm or 75×75mm SHS steel, minimum 3mm wall thickness
• Or a heavy-duty C post (channel section)

For single driveway gates (1.0m–2.0m wide):

• 75×75mm or 100×100mm SHS steel, minimum 3mm wall thickness

For double driveway gates (2.0m–4.0m total opening):

• 100×100mm SHS steel, minimum 4mm wall thickness
• Consider 150×150mm for heavy gates or high-use applications

Gate posts should be set 300–400mm deeper than standard fence posts to handle the additional leverage from the gate.

Step 2: Set the Gate Posts

The gap between gate posts determines the gate width. Allow for:

• The gate width
• Hinge clearance (typically 10–15mm each side)
• Latch clearance
• A small operational gap (5–10mm) for the gate to swing freely without binding

For a 900mm gate, set posts approximately 950–970mm apart (inside face to inside face).

Setting the posts:

1. Dig post holes to the required depth — for a 1.8m gate, dig at least 800mm deep (ideally 1.0m)
2. Set the first post plumb and brace it
3. Set the second post at the correct spacing, checking both plumb and alignment with the first post
4. Pour concrete around both posts simultaneously so you can fine-tune the spacing before the concrete sets
5. Recheck plumb and spacing, then leave to cure for at least 72 hours before hanging the gate — gate posts need longer than fence posts due to the additional load

Step 3: Mark Hinge Positions

Hinge placement affects how the gate hangs and swings. Standard hinge positions for a 1.8m gate:

• Top hinge: 200mm from the top of the gate
• Bottom hinge: 200mm from the bottom of the gate
• Middle hinge (for gates over 1.5m): centred between top and bottom hinges

For heavy gates or double driveway gates, use three hinges regardless of height.

Mark the hinge positions on both the gate post and the gate frame before welding or bolting.

Step 4: Attach the Hinges

Weld-on hinges provide the strongest connection and are preferred for permanent installations. They require welding equipment and should be hot-dip galvanised after welding to prevent rust.

Bolt-on hinges are easier to install and adjust. Use M12 or M16 bolts with large washers to distribute the load. Stainless steel or hot-dip galvanised hardware only — never zinc-plated bolts on an outdoor gate.

Attach the hinge plates to the gate post first, then hang the gate and mark the corresponding positions on the gate frame. Remove the gate, attach the gate-side hinge plates, then re-hang.

Step 5: Hang the Gate

With hinges attached to both the post and the gate frame, lift the gate into position and connect the hinges. Most bolt-on hinges have slotted holes for adjustment — leave the bolts slightly loose at this stage.

Check the gate for:

• Level — the top rail should be level (or parallel to the fence line if the fence follows a slope)
• Plumb — the gate should hang vertically
• Clearance — consistent gap between gate and post on the latch side
• Ground clearance — the gate should clear the ground by 50–75mm minimum

Once satisfied, tighten all hinge bolts fully.

Step 6: Install the Latch

For pedestrian gates, a standard spring latch or D-latch is suitable. Position the latch at a comfortable height — typically 900–1000mm from the ground.

For driveway gates, use a heavy-duty bolt latch or a lockable latch. Double gates also need a drop bolt on the passive (non-latching) leaf — this pins into the ground or a concrete socket to hold the passive leaf in position when the gate is closed.

Step 7: Fit Post Caps

Always cap gate posts to prevent water ingress into the hollow section. Water inside a steel post causes internal corrosion that's invisible until the post fails. Use powder-coated or galvanised post caps that match your Colorbond colour.

Common Problems and How to Avoid Them

Gate sags over time Cause: undersized posts or insufficient embedment depth. Fix: use larger posts and set them deeper.

Gate binds or won't close Cause: posts have moved or were set out of plumb. Fix: adjust hinge positions using slotted holes, or re-set the post.

Gate swings open on its own Cause: posts are not plumb — the gate is hanging on a slight lean. Fix: re-check post plumb and adjust.

Hinges rust Cause: zinc-plated hardware used instead of galvanised or stainless. Fix: replace with hot-dip galvanised or stainless steel hardware.

Colorbond Gate Colours

FPM stocks Colorbond fencing components in the full range of Colorbond colours including Monument, Woodland Grey, Basalt, Night Sky and Paperbark. Match your gate to your fence for a consistent finish.

Call us on 0431 235 919 or visit our Epping warehouse at 32 Fullarton Drive for gate hardware, posts and Colorbond fencing supplies.