Post spacing depends on fence type: wood privacy fences use 8 feet maximum, chain link spans 10 feet, and horizontal slat fences require 4-6 feet. Posts must be buried 1/3 of total post length with 24" minimum depth, or 6" below frost line, whichever is deeper.
📏 Post Spacing Standards by Fence Type
Wood Privacy Fence
Chain Link Fence
Vinyl/PVC Fence
Horizontal Slat Fence
Split Rail Fence
Ornamental Aluminum/Iron
⚓ Post Depth & Concrete Requirements
| Fence Height | Total Post Length | Burial Depth | Hole Diameter (4×4) | Concrete |
|---|---|---|---|---|
| 4 feet | 6 feet | 24 inches | 12 inches | 1.4 cu ft |
| 6 feet | 8 feet | 24 inches | 12 inches | 1.4 cu ft |
| 6 feet | 9 feet | 30 inches | 12 inches | 1.75 cu ft |
| 6 feet | 9 feet | 36 inches | 12 inches | 2.1 cu ft |
| 8 feet | 12 feet | 48 inches | 12 inches | 2.8 cu ft |
| Post Type | Size Required | Depth | Hole Diameter |
|---|---|---|---|
| Line posts | 4×4 (up to 6') or 6×6 (6.5-8') | 24-48 inches | 12" (4×4) or 18" (6×6) |
| Corner posts | 6×6 (upgrade regardless of fence) | +6 inches beyond line posts | 18 inches |
| 3-4 foot gates | 4×4 acceptable, 4×6 recommended | 30-36 inches | 12-15 inches |
| 5-6 foot gates | 6×6 required | 36-42 inches | 18 inches |
| 10-12 foot double gates | 6×6 minimum or 8×8 heavy | 42-48 inches | 18-24 inches |
🏗️ Concrete & Gravel Specifications
Concrete Bag Yield
Typical Bag Requirements
Gravel Base Requirements
Standard: Install 6 inches of compacted 3/4-inch crushed stone or 21AA packing gravel at bottom of each hole before setting posts.
Benefits: Provides drainage, reduces frost heaving, prevents wood rot, extends post life by 30-50%.
Calculation: Subtract gravel depth from concrete calculation. A 30-inch deep hole with 6-inch gravel base needs only 24 inches of concrete.
Fast-Setting vs Regular Concrete
Fast-Setting (Quikrete)
- • No mixing required - pour dry, add water
- • 1 gallon water per 50 lb bag
- • Sets in 20-40 minutes
- • 3,000 PSI strength
- • Costs 10-15% more
- • Perfect for fence posts
Regular Concrete Mix
- • Requires mixing
- • Sets in 24-48 hours
- • 4,000 PSI with proper curing
- • Lower cost
- • Requires overnight bracing
- • Use for structural deck posts
❄️ Frost Line Depth Requirements
Posts must extend 6 inches below local frost depth. This requirement overrides the 1/3 rule in cold climates. Never set posts less than 24 inches deep regardless of fence height.
Deep Frost States
- • Minnesota: 80 inches
- • North Dakota: 75 inches
- • Wisconsin: 65 inches
- • Michigan: 42-48 inches
Moderate Frost States
- • Illinois: 36 inches
- • Ohio: 32 inches
- • Pennsylvania: 30-36 inches
- • New York: 32-42 inches
No Frost States
- • Florida: 0 inches
- • Hawaii: 0 inches
- • Southern California: 0-12 inches
- • Gulf Coast: 0-6 inches
🪵 Wood Fence Material Specifications
Actual vs Nominal Lumber Dimensions
Lumber dimensions create calculation complexity. Always use actual dimensions for material estimates - calculating with nominal sizes produces significant errors.
| Nominal Size | Actual Size | Common Use |
|---|---|---|
| 1×6 | 3/4" × 5.5" | Privacy fence pickets |
| 1×4 | 3/4" × 3.5" | Picket fence, board-on-board |
| 2×4 | 1.5" × 3.5" | Rails (horizontal supports) |
| 4×4 | 3.5" × 3.5" | Posts (up to 6' fences) |
| 6×6 | 5.5" × 5.5" | Posts (6.5-8' fences, corners, gates) |
Rail Requirements by Fence Height
Formula: 1 rail per 2 feet of fence height.
Standard 2×4 rails (1.5" × 3.5" actual) work for most applications. Use 16-foot rails when possible to span two 8-foot sections, staggering joints for strength.
Picket Calculation Formulas
Standard Privacy Fence (butted or spaced boards)
Formula: Boards per Linear Foot = 12 ÷ (Board Actual Width + Spacing)
• 5.5" boards with zero gap: 12 ÷ 5.5 = 2.18 boards/foot
• 5.5" boards with 1" gap: 12 ÷ 6.5 = 1.85 boards/foot
• For 8-foot section with no gaps: ~18 pickets
• For 8-foot section with 1" gaps: ~15 pickets
Board-on-Board (overlapping pickets on both sides)
Requires approximately 30% more material than standard privacy. First layer boards space 1.5" apart, second layer covers gaps with 1-1.5" overlap.
• 8-foot section with 5.5" boards: 24 pickets
• 8-foot section with 3.5" boards: 38 pickets
Picket Fence (3-4 feet tall with gaps)
Traditional spacing: 2-4 inch gaps between pickets. Most codes allow 4-inch maximum gaps; pool enclosures strictly limit gaps to prevent child passage.
• 3.5" pickets with 2.5" gaps: 16 pickets per 96" section
• 3.5" pickets with 4" gaps: 12 pickets per 96" section
🔩 Fastener & Hardware Specifications
Screw Specifications for Wood Fencing
Required Sizes
- • 1.5-1.75 inches: Pickets to rails
- • 2.5 inches: General assembly
- • 3 inches: Rails to posts
- • Gauge: #8-#10 gauge
All outdoor fasteners must be hot-dipped galvanized, coated, or stainless steel. Standard screws cost 6-7 cents each versus 1-1.5 cents for ring shank nails, but screws provide superior holding power.
Quantity Formula
Total Fasteners = (Rails × 4) + (Pickets × Rails × 2)
Each rail needs 4 fasteners (2 per end). Each picket needs 2 fasteners per rail.
Example: 6-foot fence with 3 rails and 549 pickets requires 3,306 fasteners.
Post Caps
Post caps protect against water intrusion and rot, extending post life significantly.
4×4 Post Caps
Accommodate 3.375 to 4.1875-inch range (actual 3.5" × 3.5" posts)
6×6 Post Caps
Fit 5.375 to 6.125 inches (actual 5.5" × 5.5" posts)
UV-resistant ASA resin: 10-year warranty, best durability
Powder-coated metal: Cap Claw designs for flexibility
Traditional wood: Not recommended due to rot susceptibility
🚪 Gate Hardware & Specifications
Standard Gate Widths
Gate Frame Construction
Material: 2×4 lumber for gates up to 6 feet wide and 6 feet tall. Upgrade to 4×4 lumber for wider or commercial applications.
CRITICAL - Z-Bracing Direction: The diagonal brace must run from BOTTOM hinge corner to TOP latch corner, placing the brace in compression. This prevents sagging. Running the brace the opposite direction (top hinge to bottom latch) will result in gate failure.
Cross-bracing (X-pattern): Provides maximum stability for gates 8+ feet wide.
Fasteners: All joints require exterior deck screws with pre-drilled holes. Never use nails for gate construction.
| Gate Size | Weight Range | Hinge Count | Hinge Size | Extras |
|---|---|---|---|---|
| 3-4 feet wide | Up to 75 lbs | 2 minimum | 6-8" strap or T-hinges | None required |
| 4-6 feet wide | 75-125 lbs | 2-3 hinges | 8-10" heavy-duty strap | 3 hinges if over 75 lbs |
| 6 feet wide | 125-150 lbs | 3 required | 10-12" heavy-duty strap | Support wheel + anti-sag cable |
| 10-12 feet double | 125-150 lbs per leaf | 3 per leaf | 12-14" heavy-duty | Support wheels mandatory |
🏊 Pool Fence Code Requirements
Mandatory Safety Requirements
Pool barriers are strictly regulated. Non-compliance can result in fines, insurance issues, and serious child safety risks. Always check local codes - requirements vary by jurisdiction.
Minimum Height: 48 inches
Measured from ground level. Cannot be less than 4 feet under any circumstances.
Maximum Opening: 4 inches
Barriers must not allow passage of 4-inch diameter sphere. Closer-spaced members limited to 1.75-inch maximum spacing. Chain link requires 1.25-inch maximum mesh or privacy slats reducing spacing to 1.75 inches.
Gate Requirements
Must open outward from pool. Self-closing and self-latching from any open position. Latch mounted 54 inches minimum from ground or equipped with locking mechanism. Self-closing mechanisms mandatory per ICC and CPSC requirements.
Non-Climbable Zone
Horizontal members less than 45 inches apart must be on pool side of fence. Vertical spacing not exceeding 1.75 inches. Clear zone of 36 inches minimum between barrier exterior and any climbable structures or equipment.
Bottom Clearance
Maximum 2 inches for non-solid surfaces (grass, gravel). Maximum 4 inches for solid surfaces (concrete, decking).
Self-Closing Hardware Options
TruClose Hinges
- • Regular: up to 66 lbs
- • Heavy-duty: up to 154 lbs
- • Adjustable tension
- • UV-stabilized polymer
Waterson Hydraulic Hinges
- • Supports up to 440 lbs
- • 3 adjustable speed settings
- • Stainless steel construction
- • Commercial grade
📐 Height Regulations & Building Codes
Common Residential Height Standards
Front Yards
3-4 feet maximum height (standard across most jurisdictions). Often must be 50-75% open construction (picket or ornamental styles). Front setback typically extends 20 feet from property line.
Backyards
6 feet standard without permits (most common). 7-8 feet maximum with building permits and approvals. Privacy fences can be solid construction in backyards.
Corner Lots - Visibility Triangles
30-50 feet measured from corner along both roadways. 3-foot maximum fence height within triangle. Trees must have branches no lower than specified height (often 8 feet). Traffic engineer approval may be required.
Height Measurement Standards
Standard measurement: From lowest grade at fence base to top of fence.
Grade differential: When finished grades differ by less than 2 feet between properties, measure from highest parcel. Artificially altered grades (fill creating slopes exceeding 1 foot per 3 feet distance) include altered grade height in calculations.
Decorative elements: Decorative posts and caps may extend 4 inches above maximum height limits in most jurisdictions.
🔢 Material Calculation Formulas
Example: 200 Linear Feet Wood Privacy Fence (6 feet tall)
Step 1: Calculate posts
Formula: Posts = (Linear feet ÷ Spacing) + 1, round up
Posts = (200 ÷ 8) + 1 = 25 + 1 = 26 posts
Note: Corner posts share between fence lines (don't double-count). Gate posts replace line posts.
Step 2: Calculate rails
Sections = 200 ÷ 8 = 25 sections
Rails per section = 3 (6' fence uses 3 rails)
Total rails = 25 × 3 = 75 rails (2×4×8')
Use 16-foot rails when possible to span two 8-foot sections, staggering joints.
Step 3: Calculate pickets (5.5" boards, no gaps)
Formula: Boards per foot = 12 ÷ (Actual width + Gap)
Boards per foot = 12 ÷ 5.5 = 2.18
Total pickets = 200 × 2.18 = 436 pickets
Add 10-15% waste factor: 436 × 1.10 = 480 pickets to order
Step 4: Calculate concrete
Posts = 26
Bags per post = 2-3 (80 lb bags for 30" depth)
Total bags = 26 × 2.5 = 65 bags (80 lb)
Use 3 bags for corner and gate posts (deeper/larger holes)
Step 5: Calculate fasteners
Formula: (Rails × 4) + (Pickets × Rails × 2)
Fasteners = (75 × 4) + (436 × 3 × 2)
Fasteners = 300 + 2,616 = 2,916 screws
Order 3,000 screws (includes spare for errors)
Quick Reference Formulas
Posts = (Linear feet ÷ Spacing) + 1
Sections = Posts - 1
Rails per section = Fence height ÷ 24 inches
Total rails = Sections × Rails per section
Pickets per foot = 12 ÷ (Actual width + Gap spacing)
Total pickets = Linear feet × Pickets per foot
Hole diameter = 3 × Post width
📊 Waste Factors by Material
Apply waste factors by multiplying raw quantity by (1 + waste decimal). Always round up to nearest selling unit.
Wood fencing
Basic projects 10%, complex cuts 15%
Vinyl fencing
Consistent panel sizes reduce waste
Chain link
Roll flexibility allows exact cutting
Example: 100 linear feet with 10% waste = 100 × 1.10 = 110 feet to order
Extra material proves useful for repairs and accounts for cutting errors, defects, and irregular property lines.
🛡️ Pressure-Treated Lumber Requirements
Critical: All posts and lumber within 6 inches of ground require ground-contact rating with 0.15 MCA retention level (UC4A rating for permanent burial). Above-ground lumber uses lower retention at reduced cost.
Wood Species Characteristics
Western Red Cedar
- • Natural rot resistance without treatment
- • Stable dimensions, minimal warping
- • Lifespan: 20-30 years
- • Premium cost but excellent durability
Southern Yellow Pine (Pressure-Treated)
- • Economical strength, widely available
- • More warping and checking than cedar
- • Lifespan: 15-20 years with proper treatment
- • Most common residential choice
Redwood
- • Premium durability with beautiful color
- • Excellent natural rot resistance
- • Lifespan: 20-25+ years
- • Costs approximately 3× pressure-treated pine
Black Locust (Split Rail)
- • Exceptional durability for posts
- • Lifespan: 50+ years in ground contact
- • Primarily used in split rail applications
- • Superior to treated wood for longevity
Lumber Grades
#1 Grade: Fewer knots, better appearance, tighter grain
#2 (Construction) Grade: Standard framing quality with acceptable knots (most residential fencing)
Select/Premium: Minimal knots for high appearance applications
Clear Grade: No knots or defects at premium pricing
📚 Building Codes & Industry Standards
International Residential Code (IRC) R404.1 - Footings
Post footings must extend below frost line or 24-inch minimum depth. Requires concrete encasement for structural support. Posts must be set 6 inches below local frost depth.
IRC P2801 - Swimming Pool Barriers
Minimum 48-inch height. Self-closing, self-latching gates opening outward from pool. Latch 54 inches from ground. Maximum 4-inch openings. Non-climbable zone requirements. Always requires permits and inspections.
ASTM F567 - Chain Link Fence Fabric
Standards for wire gauge (11-gauge residential, 9-gauge commercial), 2-inch mesh size, coating specifications (galvanized or vinyl-coated). Ensures structural integrity and longevity.
ASTM F1083 - Pipe, Steel, Hot-Dipped Zinc-Coated (Galvanized) Welded
Specifications for fence framework posts. HF20 residential grade (16-gauge, 0.065" wall, 2" OD line posts). HF40 commercial grade (all posts 2.5-3" OD).
Local Setback & Height Requirements
Property line fences typically require 0-6 inch setback from property line. Height restrictions: 6 feet backyard standard, 3-4 feet front yard maximum. Corner lot visibility triangles limit to 3 feet. Always verify local ordinances before installation.