Deck Screws Guide

ACQ-Compatible Coated

Designed specifically for pressure-treated lumber with corrosive preservatives like ACQ (Alkaline Copper Quaternary) and CA (Copper Azole).

• Ceramic or proprietary coating prevents galvanic corrosion
• Gold, green, or tan color coating
• Superior corrosion resistance vs. standard zinc plating
• Coarse threads for softwood holding power
• Best for: Ground-contact treated lumber, wet environments

Stainless Steel (305, 316)

Premium option for maximum corrosion resistance and longevity in harsh coastal or marine environments.

• No coating needed - naturally corrosion resistant
• 305 grade for standard decks, 316 for marine
• Compatible with all wood types
• Won't react with treated lumber chemicals
• Best for: Coastal areas, hardwoods, high-end projects

Epoxy or Ceramic Coated

Heavy-duty coating systems that provide excellent protection for treated lumber applications.

• Thick coating resists abrasion and chemicals
• Available in various colors to match decking
• Excellent holding power in softwoods
• More economical than stainless steel
• Best for: Standard treated lumber decks, high-moisture areas

Multi-Purpose Exterior

Versatile screws suitable for both treated and untreated lumber with moderate corrosion resistance.

• Zinc or dacromet coating
• Good for above-ground treated lumber
• Works with cedar, redwood, and pine
• Economy option for covered decks
• Best for: Covered decks, secondary framing, railings

Composite-Specific Hidden Fasteners

Specialized screws designed to work with hidden fastener systems for composite decking boards.

• Smaller head profile for clip systems
• Stainless steel or coated for longevity
• Prevents mushrooming of composite material
• Works with major brand clip systems
• Best for: Hidden fastener installations, high-end composite decks

Composite Face Screws

Screws engineered for face-fastening composite boards without cracking, splitting, or mushrooming.

• Reverse threads near head prevent mushrooming
• Colored heads to match popular composite brands
• Smaller diameter reduces board damage
• Self-countersinking bugle head
• Best for: Budget composite installations, repairs, borders

Structural Composite Screws

Heavy-duty screws for attaching composite boards to joists and structural framing.

• Larger diameter and longer lengths
• Deep threads for composite and wood grip
• Stainless or premium coating
• Often star drive for high torque
• Best for: Composite joist attachment, stair stringers, heavy loads

Trim Head Composite Screws

Low-profile screws for fascia, trim, and detail work on composite decks where fasteners should be less visible.

• Small head diameter (approx. half of standard)
• Colored to match composite trim boards
• Fine threads for dense composite materials
• Available in multiple lengths
• Best for: Fascia boards, picture framing, trim details

Hardwood Deck Screws

Designed for exotic hardwoods like Ipe, Tigerwood, and Cumaru that are extremely dense.

• Hardened steel construction
• Fine threads for dense wood
• Trim head style common
• Stainless steel for longevity
• Always requires pre-drilling
• Applications: Exotic hardwood decking, high-end projects

Ledger Board Screws

Heavy-duty structural screws specifically engineered for attaching deck ledger boards to house structures.

• Extra length (typically 3"-6")
• Large hex washer head
• High shear and tensile strength
• Hot-dip galvanized or stainless
• Meets building code requirements
• Applications: Ledger attachment to rim joists, structural connections

Joist Hanger Screws

Short, strong screws designed specifically for metal joist hangers in deck framing.

• Short lengths (1-1/4" to 1-1/2")
• Large head for hanger holes
• Hot-dip galvanized
• High shear strength rating
• Must meet hanger manufacturer specs
• Applications: Joist hangers, structural metal connectors

Star Drive (T15, T20, T25, T30)

The most popular drive system for deck screws, offering the best combination of torque transfer and cam-out resistance.

• 6-point star pattern distributes force evenly
• Virtually eliminates cam-out when using correct bit
• Single-hand operation - bit holds screw on end
• Common sizes: T15 (small), T20 (standard), T25 (large), T30 (structural)
• Longevity: Bits last longer than square or Phillips
• Best for: All deck applications, especially power driving

Square Drive (#1, #2, #3)

Traditional favorite offering excellent torque transfer with less cam-out than Phillips. Very popular in Canada and increasingly common in the US.

• Square recess provides good bit engagement
• Less cam-out than Phillips but more than star
• Good bit availability in hardware stores
• Common sizes: #2 (standard deck screws), #3 (structural)
• Single-hand capability with magnetic bits
• Best for: General decking, traditional preference

Combination Drive (Star/Square)

Dual-drive system accepting both star and square bits, offering flexibility but slightly compromised performance.

• Works with either star or square bits
• Convenient if you have both bit types
• Slightly more cam-out than dedicated drives
• Good for mixed screw projects
• Best for: Contractors who use multiple screw types

Phillips Drive

Older style still found on some deck screws but largely replaced by star and square drives due to cam-out issues.

• Cross-shaped recess
• Prone to cam-out under high torque
• Universally available bits
• Not recommended for power driving
• Best for: Hand-driving small quantities, repairs

Bugle Head

The standard for deck screws - designed to countersink slightly below the surface without splitting wood.

• Curved underside distributes pressure
• Self-countersinking in most woods
• Flat top sits flush or slightly below surface
• Prevents splitting better than flat head
• Applications: All standard deck board installations

Flat Head

Tapered head designed to sit completely flush when properly countersunk, primarily for hardwoods or composites.

• 82° tapered underside
• Requires pre-drilling and countersinking
• Completely flush finish
• Can split softwoods if not pre-drilled
• Applications: Hardwood decking, precise flush mounting

Trim Head

Small-diameter head (approximately half the size of standard) for a more discreet fastening appearance.

• Small head diameter minimizes visibility
• Slightly raised or flush finish
• Often used with colored plugs
• Less holding power than full-size heads
• Applications: Fascia, trim boards, picture framing, high-visibility areas

Deck Board Fastening

• Standard method: 2 screws per board per joist
• Wide boards (>6"): 3 screws per joist recommended
• Joist spacing: Typically 16" on center
• Formula: (Deck square footage ÷ Board width in feet) × (Deck length ÷ Joist spacing) × 2
• Example (12×16 deck, 16" joists, 5.5" boards): ~330 screws + 10% waste = 365 screws

Framing & Structure

• Joist hangers: 4 screws per side minimum (8 total per hanger)
• Rim joist blocking: 3 screws per connection
• Ledger board: Per code, typically every 16" (varies by load)
• Railing posts: 4-6 structural screws per post
• Always buy 10-15% extra for mistakes, splits, and adjustments

Standard Deck Board Attachment

• Two screws per joist: Position 3/4" to 1" from each edge
• Boards 6" or wider: Use 3 screws per joist to prevent cupping
• End joints: Must fall on joist center - use 2 screws per board end
• Stagger end joints: Alternate board ends across deck for strength
• First/last boards: May require toe-screwing if butting against house/fascia

Composite Board Requirements

• Follow manufacturer specs: Spacing varies by brand
• Edge distance: Typically 1" minimum from edge
• End distance: Usually 2" minimum from board ends
• Hidden fasteners: Follow clip manufacturer installation guide
• Temperature gaps: Leave expansion space per manufacturer (typically 1/4" to 1/2")

Hardwood Decking

• Always pre-drill: Pilot hole = 75% of screw diameter
• Countersink: Required for flat or trim head screws
• Edge distance: Minimum 1" to prevent splitting
• Consider plugs: Wood plugs hide screws in visible areas
• Hidden fasteners preferred: Creates clean surface appearance

Picture Frame Borders

• Miter joints: Use trim head screws, 2-3 per joint
• Face screws: Position to be covered by picture frame
• Border boards: Run perpendicular to field boards
• Extra blocking: Install blocking under border board edges
• Toe-screwing: May be needed at corners

Tool Selection

• Impact driver: Best for deck screws - high torque, no cam-out
• Cordless drill: Acceptable with fresh battery and quality bits
• Autofeed screwgun: Professional option for large decks (100+ sq ft)
• Bit quality: Use impact-rated bits with star/square drives
• Magnetic bit holder: Enables one-handed operation
• Clutch/torque setting: Essential for composite to prevent over-driving

Driving Technique

• Perpendicular angle: Keep drill at 90° to board surface
• Steady pressure: Push firmly while driving - prevents cam-out
• Two-stage driving: Drive fast to start, slow near flush
• Final seating: Stop when screw head is flush or slightly below
• Don't overdrive: Mushrooming, splitting, or stripping = failure point
• Pilot holes optional: Most softwoods don't need them except near ends

Pre-Drilling Guidelines

• Hardwoods: Always pre-drill at 75% of screw diameter
• Composite: Pre-drill per manufacturer requirements
• Board ends: Pre-drill within 2" of end to prevent splitting
• Treated lumber: Pre-drill near edges to prevent splitting
• Countersink: Use countersink bit for flat head screws
• Clearance holes: Top board gets larger hole for lag connections

Splitting & Cracking

Causes:

• Screws too close to board edge or end
• No pilot hole in hardwood or near ends
• Driving screws in cold weather
• Board is dried out or brittle

Solutions:

• Maintain 3/4" minimum edge distance, 2" end distance
• Pre-drill pilot holes near board ends
• Install when temperature is above 40°F
• Use Type 17 point screws that reduce splitting

Squeaking Deck Boards

Causes:

• Insufficient screw penetration into joist
• Board movement due to loose fastening
• Screws not hitting joist center
• Wet lumber that shrunk after drying

Solutions:

• Use screws with minimum 1-1/2" joist penetration
• Add additional screws to secure loose boards
• Mark joist locations clearly before driving
• Use kiln-dried lumber when possible

Stripped or Broken Screws

Causes:

• Wrong bit size causing cam-out
• Over-tightening with excessive torque
• Hardwood without pilot hole
• Low-quality screws with weak metal

Solutions:

• Use correct size bit and fresh, sharp bits
• Adjust clutch setting or driver speed
• Always pre-drill hardwoods
• Buy quality screws with hardened steel

Composite Mushrooming

Causes:

• Over-tightening composite deck screws
• Using wrong screw type (wood screws)
• No pilot hole in dense composite
• Installing in extreme heat

Solutions:

• Use composite-specific screws with reverse threads
• Pre-drill per manufacturer requirements
• Set torque/clutch to stop at flush
• Install in moderate temperatures (60-80°F)