Introduction
The difference between a fence that stands straight for 15 years and one that leans by year three is rarely the lumber — it’s the installation details: string lines, post depth, drainage, and fastener choice. Estimating gets you the right materials; these are the practices that make them perform.
The Wood Fence Calculator handles the quantities — this guide covers the craft. Below are the installation tips that separate professional results from weekend-warrior wobble, organized in the order you’d actually use them on the job.
Layout and String Lines
Run two lines, not one
Set a string line at the top of the pickets and a second at ground level. The top line keeps heights consistent across uneven ground; the bottom line keeps the run straight. Batter boards at the ends (stakes with a crosspiece) hold the strings while you dig — a single stake gets knocked over the first time someone trips on it.
Mark posts before you dig
Spray-paint every post location from your measured spacing before the auger arrives. Measure from one end continuously rather than post-to-post — cumulative tape error is how 6-ft spacing drifts to 6 ft 3 in by the tenth post. For the measurement technique, see the estimating guide.
Post Setting
The 1/3 rule is a minimum, not a target
One-third of the total post in the ground — 3 ft (0.91 m) of burial for a 6-ft (1.83 m) fence, so buy 9-ft (2.74 m) posts. On windy sites and in loose soil, go deeper rather than wider: depth resists overturning far better than a fat, shallow hole. In cold climates, the post base must also sit below the local frost line — the code compliance guide explains what to check with your local authority.
Concrete vs gravel backfill
| Method | Best when | Watch out for |
|---|---|---|
| Concrete (full hole) | Windy sites, tall privacy fences, loose soil | Traps moisture against the post if the top isn’t crowned to shed water |
| Concrete (top 2/3 only) | Most residential jobs | Compact the soil in the bottom third first |
| Compacted gravel | Wet/clay soil, frost-heave areas | Needs tamping in 6-in lifts; slightly less rigid |
The crown matters more than the mix: dome the concrete 1–2 in (2.5–5 cm) above grade and slope it away from the post so water never pools at the wood. A flat or dished concrete top is a post-rot accelerator.
Set posts a hair high
Posts settle. Set each post 0.5–1 in (1–2.5 cm) above its final height mark and let gravity finish the job — you can always trim a high post, but you can’t stretch a settled one.
Pickets and Rails
Start pickets at the highest point
On sloped ground, begin at the high end and let the fence step down. Starting low means ripping the last pickets at an awkward angle. Each step should drop by a full picket-course increment so the top line stays level between posts.
Leave a ground gap
Keep picket bottoms 2–3 in (5–7.5 cm) above grade. Wood wicking soil moisture rots from the bottom up; the gap also lets you trim grass without chewing the fence. Cut pickets rather than burying them to follow a dip.
Pre-drill near ends
Cedar splits. Pre-drill picket ends and any rail closer than 1 in (2.5 cm) to an edge — it adds minutes and saves dozens of split boards over a 150-ft run.
Two fasteners per rail crossing
One screw per picket-rail crossing lets the board pivot and cup over time. Two fasteners (top and bottom rail positions, diagonally offset) lock the board flat. Use exterior-rated screws or ring-shank nails — plain nails back out within a couple of seasons. Fastener math and corrosion notes are in the material guide.
Finishing
Stain before you hang (or immediately after)
Pre-staining pickets before installation coats all six faces including edges and ends — the faces you can’t reach once boards are up. If pre-staining isn’t practical, stain within 4–6 weeks of installation before UV greys the surface. Coverage planning (150–300 sq ft/gal) is worked in the formula guide.
Don’t seal the bottoms shut
End grain absorbs and releases moisture fastest. Seal cut ends with the same stain — but never cap picket bottoms with a waterproof membrane that traps moisture inside the board.
Working Smart
- Rent the auger, buy the level. A two-person power auger turns a weekend of post holes into an afternoon; a 4-ft level you’ll keep. Rental ≈ $75–$100/day.
- Sort lumber on delivery. Cull warped and split pickets immediately — suppliers replace defects fast if you report them within days, not weeks.
- Work in the order: posts, rails, pickets. Let concrete cure 24–48 hours before hanging rails. Rushing this step is the top cause of leaning fences.
- Keep a cut list. For a 150-ft run you need 330 pickets at ~2.2/ft — cut in batches of 20 and check the string line every batch. The pre-install checklist has the full sequence.
Related Guides
- Wood Fence Complete Guide — the flagship estimating overview.
- Common Fence Estimating Mistakes — the errors these tips prevent.
- Wood Fence Material Guide — species, treatments, and fastener selection.
- DIY vs Pro — which of these tasks are worth hiring out.
- Estimating Guide — measuring the run these tips build on.
Frequently Asked Questions
Should fence posts be set in concrete or gravel?
Concrete for wind-loaded privacy fences and loose soil; compacted gravel where drainage or frost heave is the bigger enemy. Either way, crown the top to shed water and bury one-third of the post minimum.
How long should concrete cure before hanging rails?
24–48 hours for standard mix before loading the posts with rails and pickets. Full strength takes ~28 days, but the fence load is light enough that two days of cure is the practical standard.
Should I stain a fence before or after installation?
Before is better — pre-staining coats edges and ends you can’t reach once boards are hung. If you missed that window, stain within 4–6 weeks of installation.
How do I keep a fence straight on a slope?
Step the panels: keep each section level and drop height at the posts, starting from the high end. Material counts barely change; post lengths grow on the downhill side.
Why do fence pickets warp?
Uneven drying — one face in sun, one in shade — plus single fasteners that let boards pivot. Two fasteners per rail crossing, consistent stain coverage, and keeping boards off the soil all reduce warping.
Get Your Number
Good installation is a sequence: straight lines, deep posts, drained footings, two fasteners per crossing, stain on schedule. Get the quantities right with the Wood Fence Calculator, then work the sequence — the fence you build this weekend has to stand for fifteen years, and these are the details that decide it.
Disclaimer: Installation tips are general planning guidance, not engineering advice. Soil, wind, and frost conditions vary; verify post depth and footing requirements locally and consult a licensed professional or your local building authority for structural or code-related decisions.
