How to Build a Privacy Fence

Before you stake or dig anything, confirm the exact location of your property lines. A fence on the wrong side of the line is a neighbour dispute waiting to happen and can result in forced removal at your expense. Pull your property survey from your mortgage closing documents. If none exists, hire a licensed land surveyor ($300–$800) — a county GIS parcel map is a useful rough reference but is not legally binding. Many municipalities require a fence permit for fences over 4 ft, front-yard fences, and corner-lot fences. Fees are typically $25–$100. Most jurisdictions also require a 6–12 in setback from the property line. Call 811 before any digging, and get HOA approval in writing before purchasing a single board.

Stake the fence line using mason's string and walk the entire run to check for grade changes. You need to decide before setting a single post whether you want a racked fence (follows the slope continuously) or a stepped fence (stays level between posts, drops in increments). Racked fences look more natural on gradual slopes; stepped fences are better for steep grades and are easier to build. Space posts a maximum of 8-ft on-centre for a 6-ft privacy fence — 6-ft spacing is stiffer and better for high-wind areas or soft soil. For 100 LF at 8-ft spacing: 100 ÷ 8 = 12.5 spans, rounding to 13 + end posts + gate posts = 17–18 posts depending on corners. Mark every location with spray paint and verify spacing by measuring the full run.

Post hole diameter should be at least 3× the post width — minimum 12 in for a 4×4 post, though 10–12 in is standard for fence posts. Depth rule: one-third of the total post length, plus 6 in for the gravel drainage base. For a 6-ft fence using 10-ft posts: ⅓ of 10 ft = 40 in + 6 in gravel = 46 in — which in most northern climates also clears the frost line. Always confirm with your local building department. After digging, add 6 in of pea gravel and tamp lightly before any concrete. This drainage base is the simplest thing you can do to extend post life — standing water at the post base accelerates rot even in UC4B treated lumber.

Place each post in its hole, brace it plumb in two directions with 2×4 kickers staked to the ground, and pour concrete around it. Quikrete Fast-Setting is ideal for fence posts — pour it dry around the post, add water per bag label, and it sets in 20–40 minutes without mixing. This lets you move down the line and set multiple posts in one day. Crown the concrete surface at grade so water drains away from the post rather than pooling. After setting each post, measure to the previous one to confirm spacing before the concrete stiffens. Let all posts cure 24–48 hours before attaching rails.

Snap a chalk line across all posts at 6 ft above finished grade, verify it from both ends, then cut every post at that mark in a single pass with a circular saw or reciprocating saw. On sloped ground, post heights will vary — each post must be individually measured from grade, not from the top of the previous post. Immediately after cutting, apply end-cut wood preservative to every post top and install a post cap. The exposed end grain is the most vulnerable point on the entire fence — rain hits it directly and it wicks moisture deep into the post. Install 3 rails per panel: top at 7½ in below post top, middle at mid-height, bottom at 8 in above grade. Attach with rail brackets for speed and strength, or toenail with 3-in exterior coated screws.

Cedar is the right choice for 6-ft privacy fence pickets: naturally rot and insect resistant without chemical treatment, dimensionally stable, and takes penetrating stain well. Hold the first picket plumb and set it off the post face rather than flush to the post — this small gap allows the rail to shed water freely. Use a story pole (a scrap 1×2 marked with your gap and height positions) to set every picket without measuring each individually. Standard gap is 5/8 in between pickets. Leave a minimum 2-in gap between the picket bottom and grade — cedar will rot if it contacts soil. Drive nails or screws into each rail: 2 fasteners per rail per picket.

Build the gate frame on a flat surface before hanging it. Cut two vertical stiles the height of the fence opening and two horizontal rails the opening width minus 1 in on each side for swing clearance. Assemble into a rectangle, then add a diagonal tension brace running from the bottom hinge-side corner up to the top latch-side corner. This diagonal is structural — without it, the gate will sag within a year regardless of hinge quality. Attach pickets to the frame flat on the ground before hanging. For a single walk-through gate, keep the opening 36–42 in — gates wider than 4 ft sag even with diagonal bracing. Hang with at least 2 heavy-duty hinges (3 for gates over 5 ft tall or 30 lb). Shim the bottom of the gate ½ in above grade before securing hinges — most gates drop ¼–½ in in the first year.

Cedar weathers to a natural silver-grey if left unfinished — many people prefer this look and it requires no maintenance. If you want to preserve the warm brown tone, apply a penetrating semitransparent stain after the cedar has dried for at least 6 months. Film-forming products (solid stains, paints) will peel and chip on cedar within 3–5 years as the boards expand and contract — do not use them. The most important finishing tasks are mundane but critical: apply end-cut preservative to every cut post top, keep vegetation off the fence boards, and maintain a 2-in gap at the picket bottoms. Check post bases at grade every few years with a screwdriver — soft wood means rot has started.