How to Build a Timber Privacy Screen with Slats

What timber species, fasteners, and concrete meet Australian building standards?

Step-by-Step Guide

Step 1: Set Out and Excavate Footings

1️⃣ Clear the build area of vegetation and debris. Run a tight nylon stringline representing the face of the posts to ensure the screen runs straight.

2️⃣ Mark post locations. Maximum post spacing should not exceed 1200mm to 1500mm centre-to-centre to avoid timber slat deflection over time.

3️⃣ Dig post holes to a minimum depth of 600mm for an 1800mm-high screen (a standard rule of thumb is 1/3 of the total post length in-ground). Hole diameter should be roughly 250mm to 300mm. Add 50mm of blue metal gravel to the base of each hole to assist drainage away from the post end.

Step 2: Install and Plumb the Posts

1️⃣ Coat cut ends of in-ground timber with a timber preservative (such as Tanalised Enseal) to prevent premature rot.

2️⃣ Set the corner or end posts into the holes. Use temporary timber bracing (e.g., 70x35mm pine stakes) screwed into the posts to hold them rigidly.

3️⃣ Check for plumb on two adjacent faces using a 1200mm spirit level. Adjust braces until perfectly plumb.

4️⃣ Pour dry rapid-set concrete around the post while adding clean water in layers as per manufacturer specifications, or mix concrete in a wheelbarrow prior to pouring. Slope the top concrete collar away from the timber post at ground level to shed water. Allow a minimum of 2 to 4 hours to cure before loading.

Step 3: Trim Posts and Install Stiffeners

1️⃣ Mark the desired finished height on your end posts using a line level or water level. Snap a chalk line across intermediate posts and cut posts square using a reciprocating saw or circular saw with a guide.

2️⃣ If the post span exceeds 1200mm, plan to install a vertical 42x19mm stiffener cleat down the centre rear of the screen later to eliminate slat warping.

Step 4: Pre-Finish Timber Slats

1️⃣ Lay all slats out across sawstools. Sand off any handling marks or mill glaze with 80–120 grit abrasive paper.

2️⃣ Apply one complete coat of penetrating timber decking oil to all four sides (including ends) before installation.

💡 Pre-coating timber all-round seals the back face that becomes completely inaccessible once fixed against the posts, dramatically reducing the risk of cupping.

Step 5: Fix the First Slat

1️⃣ Start at the top of the posts to guarantee a clean, flush horizontal line at eye level, working your way down toward the ground.

2️⃣ Align the first 70x19mm or 42x19mm slat flush with the top and sides of the posts. Secure with quick-grip clamps.

3️⃣ Using a specialised countersinking bit, drill two pilot holes per post intersection. Fix using 10G x 50mm stainless steel decking screws. Drive screw heads flush; do not over-drive and rupture the timber grain.

Step 6: Systematic Slat Installation

1️⃣ Insert your uniform 10mm or 15mm spacer blocks tight up against the underside of the newly fixed slat.

2️⃣ Push the next slat up against the spacers, clamp it in position at each post, and pre-drill through your pilot holes.

3️⃣ Check alignment with the spirit level every 3 to 4 slats to catch and correct minor variations before they compound.

4️⃣ Once all horizontal slats are fixed, screw the rear vertical cleat at the mid-span point from the rear into each slat using 8G x 30mm screws (ensuring screws do not penetrate the visible front face).

Step 7: Final Finishing

1️⃣ Clean off any residual surface dust or tannin marks using a dedicated oxalic-acid-based timber cleaner if necessary.

2️⃣ Apply the second coat of penetrating exterior timber oil to the front face and edges to fully seal screw points and cut ends.

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