How to Install Aluminium Slat Fencing: A Factory's Step-by-Step Guide

Aluminium slat fencing looks simple — posts, slats, done. But the difference between a fence that looks factory-made and one that looks homemade comes down to a handful of details: post depths, consistent gaps, and how you handle slopes. This guide walks through the full install the way we'd want our own product put up.

Tools and materials

Tools: string line and pegs, post-hole digger or auger, spirit level (1200 mm), tape measure, drill/driver, rubber mallet, quick-set concrete mix, wheelbarrow or mixing tub, angle grinder with aluminium cutting disc (for trimming slats), spacers or packers for gaps.

Materials per run: posts (one per ~2.4 m plus gate posts), slats to suit your height and gap, top/bottom rails or side channels, fixings, post caps. Our fence calculator builds the exact list from your measurements.

Step 1 — Set out the line

Run a string line between your end points at the finished fence height. Mark every post position — standard spacing is 2.4 m centre to centre to match common slat/panel lengths. Check the line is straight and square to boundaries; a fence that's 20 mm out at the start is 100 mm out by the end of a long run.

Call your local "dial before you dig" service (1100 in Australia, 811 in the US) before any hole goes in the ground. Hitting a service line turns a weekend job into a very expensive one.

Step 2 — Set the posts

1. Dig to 600 mm deep (minimum) for a 1.8 m fence — the rule of thumb is one-third of the post in the ground. In soft soil or high-wind areas, go 700–800 mm.
2. Set the two end posts first, plumb in both directions, braced while the concrete sets.
3. Run the string line between end posts and set intermediates to it — every post face flush to the line.
4. Concrete, don't just backfill. Use a wet mix, crown it slightly above ground level so water runs off the post base, not into it.
5. Let it cure 24 hours before hanging anything. This is the step everyone rushes and regrets.

Step 3 — Fix channels and rails

Fix your side channels or top/bottom rails to the posts, checking level on every one. Channels must be parallel — if the top channel drifts 5 mm over a run, your slat gaps will visibly taper. Pre-drill aluminium before driving screws: it stops the bit wandering and protects the powder-coat from cracking around the hole.

Step 4 — Fit the slats

Start from the bottom and work up (or top-down if your system specifies it). Use packers to hold a consistent gap — never eyeball it; the eye picks up 2 mm of variation across a run. Tap slats home with a rubber mallet, never a steel hammer. Fix through the channel into the slat end, not through the slat face — face-fixing leaves visible screw heads and a water entry point on every board.

Step 5 — Handle slopes: racking vs stepping

Two methods, and choosing wrong is the most common DIY failure:

• Racking — slats follow the slope in a straight diagonal line. Use it on gentle, even grades. Looks clean, minimal cutting.
• Stepping — each bay stays level and drops at the post, like stairs. Use it on steeper or uneven ground. Each step needs the post set deeper on the low side.

Rule of thumb: if the fall is more than ~100 mm per 2.4 m bay, step it. Trying to rack a steep slope leaves wedge-shaped gaps under the fence that look wrong and let pets through.

Step 6 — Gates and finishing

Gate posts get heavier footings — 800 mm deep minimum, and consider a larger post section. Hang the gate, check it swings clear and latches without lifting, then fit post caps. Walk the full run sighting along the top: any slat sitting proud gets eased back now, not later.

5 mistakes that ruin the finish

1. Eyeballing the gaps. Use packers on every slat. Inconsistent gaps are visible from the street.
2. Screws through the powder-coat face. Always fix through channels/ends. A rust streak starts at every face puncture.
3. Posts too shallow or rushed concrete. A leaning post in year two means rebuilding the bay. 600 mm minimum, 24-hour cure.
4. Wrong post spacing. Stretching to 2.7 m to "save a post" leaves slats spanning too far — they bow, rattle in wind, and void the neat look.
5. Cutting slats with a steel blade. Use an aluminium cutting disc and deburr the cut. A rough cut tears the powder-coat back from the edge.

FAQ

How deep should fence posts be for aluminium slat fencing?

600 mm minimum for a 1.8 m fence (one-third in the ground), deeper in soft soil, sand or high-wind zones. Gate posts: 800 mm minimum.

What spacing between posts?

2.4 m centre to centre is the standard — it matches common slat lengths so you don't cut every board.

Can aluminium slat fencing go on a slope?

Yes — rack gentle grades, step steeper ones (see Step 5). Either way, keep the bottom of the fence within 100 mm of the ground along the run.

How long does installation take?

A handy DIYer: roughly a day per 10–12 metres including post curing time. A two-person crew: 20–30 metres a day on flat ground.

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