Fence Building Guide

Post spacing, concrete footing requirements, board patterns, and gate construction for wood privacy fences

Wood Privacy Fence Basics

A wood privacy fence is a solid barrier fence typically 6-8 feet tall, designed to provide privacy, security, and noise reduction. It consists of vertical posts set in concrete, horizontal rails connecting the posts, and vertical pickets or boards attached to the rails.

Privacy fences are most commonly built from cedar, pressure-treated pine, or redwood. Cedar and redwood offer natural rot resistance and attractive grain patterns, while pressure-treated lumber provides durability at a lower cost.

Key Components: A privacy fence has three main parts: posts (vertical support members set in concrete), rails (horizontal connecting members), and pickets or boards (vertical face boards that create the privacy screen).

Post Spacing by Fence Height

Standard Post Spacing Guidelines

Fence Height	Maximum Post Spacing	Recommended Post Size	Notes
3-4 feet	8 feet O.C.	4×4	Garden fences, decorative borders
4-6 feet	8 feet O.C.	4×4	Most common privacy fence height
6-8 feet	6-8 feet O.C.	4×4 or 6×6	Use 6×6 for maximum stability or windy areas
8+ feet	6 feet O.C.	6×6	May require engineering approval in some jurisdictions

Wind Load Consideration: In areas with high winds or exposure, reduce post spacing to 6 feet O.C. and consider upgrading to 6×6 posts for fences 6 feet or taller.

Calculating Number of Posts Needed

Formula:

Number of posts = (Fence length ÷ Post spacing) + 1

Example: For a 100-foot fence with 8-foot post spacing:

Divide fence length by spacing: 100 ÷ 8 = 12.5
Round down: 12
Add 1 for the final post: 12 + 1 = 13 posts
Add extra posts for corners and gates

Post Hole Depth and Diameter

Post Hole Sizing Requirements

Post Size	Hole Diameter	Depth (Standard)	Depth (Frost Line)
4×4	10-12 inches	24-30 inches	Below frost line + 6"
6×6	12-16 inches	30-36 inches	Below frost line + 6"

Frost Line Rule: In cold climates, posts must be set below the frost line to prevent heaving. Check your local frost line depth and dig holes 6 inches deeper. Typical frost lines range from 12 inches (warm climates) to 48+ inches (northern states).

General Depth Rule

Rule of Thumb: Post holes should be dug to a depth equal to 1/3 to 1/2 of the above-ground height of the fence.

6-foot fence: 24-36 inch hole depth
8-foot fence: 32-48 inch hole depth

Always use the deeper of: (1) the 1/3 rule, or (2) frost line + 6 inches.

Concrete vs Gravel Footings

Method	Best Use	Pros	Cons
Concrete Footing	Permanent fences, tall fences, clay or sandy soil	Maximum stability, permanent, handles wind loads	More expensive, harder to adjust, can trap moisture
Gravel Footing	Temporary fences, well-draining soil, smaller fences	Better drainage, easier to adjust, lower cost	Less stable, not suitable for tall fences or high winds
Hybrid Method	Best of both worlds	Good drainage, stable, moderate cost	More complex installation

Concrete Footing Installation

Dig hole to proper depth and diameter
Add 4-6 inches of gravel at bottom for drainage
Set post in center of hole
Brace post plumb and level
Fill hole with concrete (80 lb bags: 2-3 for 4×4, 3-4 for 6×6)
Slope concrete away from post at top to shed water
Let cure 24-48 hours before continuing

Gravel Footing Installation

Dig hole to proper depth, 12 inches diameter
Set post in center of hole
Brace post plumb and level
Fill hole with crushed gravel (3/4" stone)
Tamp every 6 inches with tamper or 2×4
Continue filling and tamping to 2-3 inches below grade
Top with soil and slope away from post

Hybrid Method (Recommended)

Dig hole and add 6-8 inches of gravel at bottom
Set post and brace plumb
Fill lower 2/3 of hole with concrete
Fill upper 1/3 with gravel for drainage
Top with soil sloped away from post

This method provides stability while preventing water from pooling around the post base, extending post life.

Rail Sizing and Placement

Rail Size by Fence Height

Fence Height	Rail Size	Number of Rails	Rail Placement
3-4 feet	2×4	2 rails	8-10" from top and bottom
4-6 feet	2×4	2-3 rails	8-10" from top, 8-10" from bottom, center if 3 rails
6-8 feet	2×4	3 rails	8-10" from top and bottom, evenly space middle rail

Rail Installation: Rails should be installed with the 4-inch dimension vertical (on edge) for maximum strength. This orientation provides better support for the pickets and resists sagging.

Rail Attachment Methods

Face-mounted: Rails attach to the face of posts using brackets or screws. Easier installation, works for both sides of fence.
Between posts: Rails fit between posts in notches or with hangers. Cleaner look, more challenging installation.
Toe-nailed: Rails are angle-nailed directly into posts. Traditional method, requires careful nailing to prevent splitting.

Recommended fasteners: Use 3" exterior-grade screws or hot-dipped galvanized nails. For brackets, use joist hanger nails or appropriate screws.

Picket Spacing for Different Styles

Fence Style	Picket Size	Spacing/Gap	Description
Privacy (Solid)	1×6 or 1×8	0" (butted tight) or 1/4"	Pickets placed side-by-side with no gaps for maximum privacy
Shadowbox	1×6	1.5-2" gap, alternating sides	Pickets alternate on both sides of rails, overlapping gaps for privacy with airflow
Board-on-Board	1×6	2-3" gap, single side overlap	Similar to shadowbox but all pickets on one side, second layer covers gaps
Semi-Privacy	1×4 or 1×6	1-3" gaps	Evenly spaced pickets with gaps for partial view and airflow

Privacy Fence Installation

Start from one end or work from both corners toward middle
Use a spacer (1/4" or 1/2") for consistent gaps to allow wood expansion
Keep picket tops level using a chalk line or string
Attach with 2 screws/nails per rail (1.5-2" from edges)
Leave 2-3" gap at bottom for air circulation and weed trimmer clearance

Shadowbox Fence Installation

Install pickets on one side first, spacing 1.5-2" apart
Use spacer block for consistent gaps
Install second set of pickets on opposite side, centered over gaps
Pickets should overlap by at least 1" on each side of gap
Provides privacy while allowing air flow through fence

Picket Material Calculations

Privacy Fence Formula:

Pickets needed = (Fence length × 12) ÷ Picket width

Example: 100-foot fence with 6-inch (5.5" actual) pickets:

100 × 12 = 1,200 inches of fence length
1,200 ÷ 5.5 = 218 pickets
Add 10% for waste: 218 × 1.1 = 240 pickets

Gate Construction and Hardware

Gate Size Guidelines

Gate Type	Maximum Width	Frame Size	Notes
Walk-through Gate	3-4 feet	2×4	Most common residential gate size
Wide Single Gate	5 feet	2×4 or 2×6	Use anti-sag cable or brace
Double Drive Gate	8-16 feet (total)	2×6	Each panel 4-8 feet, requires heavy-duty hinges

Gate Frame Construction

Cut two vertical stiles (full gate height) from 2×4 lumber
Cut top and bottom rails (gate width minus stile widths)
Assemble frame with 3" exterior screws or through-bolts
Add diagonal brace from bottom hinge-side corner to top latch-side corner
Attach pickets to frame matching fence style
Gate width should be 1/2" to 3/4" less than opening for clearance

Anti-Sag Cable: For gates over 4 feet wide, install a turnbuckle cable from the top hinge-side corner to the bottom latch-side corner. Tighten turnbuckle to lift and support the gate, preventing sagging.

Gate Post Requirements

Post size: Use 6×6 posts for gates up to 5 feet wide, 4×4 acceptable for 3-4 foot gates
Post depth: Set gate posts 6-12 inches deeper than fence posts
Post spacing: Opening width = gate width + 1.5-2 inches for hardware clearance
Concrete footing: Always use concrete for gate posts, minimum 12-inch diameter hole

Gate Hardware Selection

Hardware Type	Size Recommendation	Notes
Hinges	2-3 heavy-duty T-hinges or strap hinges	Use 3 hinges for gates over 5 feet tall. Galvanized or stainless steel.
Latch	Heavy-duty gate latch or cane bolt	Must be operable from both sides for walk-through gates
Gate Spring	Adjustable tension spring	Optional for self-closing gates, installs on hinge side
Drop Rod	1/2" rod with bracket	For double gates, secures one panel to ground

Gate Installation Steps

Set gate posts plumb and let concrete cure fully (48+ hours)
Position gate in opening with 1/2" clearance all around
Use blocks or shims to hold gate at proper height
Mark hinge locations on post (top 6-8" from top, bottom 8-10" from bottom)
Attach hinges to gate frame first, then to post
Test swing and adjust as needed
Install latch hardware at comfortable height (36-42")

Rot Prevention Techniques

Wood Selection for Longevity

Cedar: Natural rot resistance, 15-20 year lifespan, attractive appearance, no treatment needed
Redwood: Excellent rot resistance, 20-25 year lifespan, premium price, beautiful color
Pressure-treated pine: Chemical rot resistance, 15-20 year lifespan, most economical option
Treated posts: Always use pressure-treated lumber rated for ground contact (.60 retention) for posts

Post Protection Methods

Post caps: Install decorative or flat caps on all posts to shed water
Gravel base: Place 4-6 inches of gravel at bottom of post hole before setting post
Concrete slope: Slope concrete away from post at ground level to prevent water pooling
Post anchors: Consider metal post anchors that elevate wood above concrete
Sealer on cut ends: Apply end-cut preservative to any fresh cuts in treated lumber

Fence Board Protection

Ground clearance: Leave 2-3 inches between bottom of pickets and ground
Stain or seal: Apply exterior wood stain or sealer within 2-6 months of installation
Avoid face-grain contact: Position rails and pickets so end grain faces up to shed water
Kickboard alternative: Use rot-resistant board (or no board) at ground level

Finish and Maintenance Schedule

Initial application: Wait 2-6 months for new wood to weather, then apply solid stain, semi-transparent stain, or clear sealer
Re-staining: Every 2-3 years for solid stain, 2-4 years for semi-transparent, annually for clear sealers
Cleaning: Power wash fence before re-staining, use low pressure to avoid damaging wood
Inspection: Check posts for rot annually, especially at ground line. Replace damaged sections promptly

New Pressure-Treated Wood: Modern pressure-treated lumber uses water-based treatments. Let it dry for 2-6 months before staining. Wood is ready when water beads on surface rather than soaking in.

Tools and Materials Needed

Tools

Post hole digger or auger
4-6 ft level
String line and stakes
Tape measure
Circular saw or miter saw
Drill/driver with bits
Speed square
Chalk line
Hammer
Post level (3-way level)
Wheelbarrow or mixing tub
Shovel and tamper

Materials

Posts (4×4 or 6×6, ground contact rated)
Rails (2×4 lumber)
Pickets or fence boards
Concrete mix (80 lb bags, 2-4 per post)
Gravel (3/4" crushed stone)
3" exterior-grade screws or galvanized nails
Gate hardware (hinges, latch, spring)
Post caps
Wood stain or sealer
Temporary bracing (1×4 or 2×4 scraps)

Safety and Code Considerations

Call Before You Dig: Contact 811 or your local utility locating service at least 2-3 business days before digging to have underground utilities marked. Hitting gas, electric, or water lines can cause serious injury or death.

Property Lines and Setbacks: Verify your property lines before building. Most jurisdictions require fences to be set back from property lines. Check with your local building department and HOA for setback requirements and height restrictions.

Permits: Many areas require building permits for fences over a certain height (typically 6 feet). Check local codes before starting. Failure to obtain permits can result in fines and required removal.

Pressure-Treated Lumber: Wear gloves when handling pressure-treated wood. Avoid burning treated wood as it releases toxic fumes. Wear a dust mask when cutting. Wash hands after handling.

Note: Fence regulations vary significantly by location. Some areas have specific requirements for fence height, setbacks, appearance (which side faces neighbor), and construction methods. Always verify local codes and obtain necessary permits before beginning construction.

Quick Reference Summary

Standard 6-Foot Privacy Fence

Posts: 4×4 pressure-treated, 8 ft O.C., 24-36" deep
Rails: 2×4, three rails (top, middle, bottom)
Pickets: 1×6 cedar or treated, butted tight or 1/4" gap
Footing: 2-3 bags concrete per post with gravel base

Key Measurements

Post hole depth: 1/3 of above-ground height minimum
Post spacing: 8 feet maximum for 6 ft fence
Rail placement: 8-10 inches from top and bottom
Ground clearance: 2-3 inches below pickets
Gate clearance: 1/2 to 3/4 inch all around

Disclaimer: This guide provides general information about wood fence construction. Local building codes, soil conditions, climate, and property regulations vary significantly. Always consult with local authorities, obtain necessary permits, and follow manufacturer specifications for all materials. When in doubt, hire a licensed fence contractor.