Deck Board Spacing: How Much Space Should You Leave Between Deck Boards?
Deck board spacing refers to the gap between individual deck boards and plays a critical role in how a deck performs over time. Proper spacing allows for water drainage, airflow, and natural movement of the boards, helping prevent warping, cupping, mold, and premature deterioration. Whether you are building with redwood, cedar, pressure treated lumber, hardwood, or composite decking, getting deck board spacing right is essential for a long lasting deck.
This guide explains how much space to leave between deck boards, why spacing matters, and how spacing recommendations vary by material and conditions.
Why Deck Board Spacing Matters
All decking materials move over time. Wood expands and contracts with changes in moisture, while composite decking responds primarily to temperature. Without proper spacing, deck boards can push against one another, trap moisture, or create standing water on the deck surface.
Correct deck board spacing helps:
● Accommodate natural expansion and contraction
● Improve airflow so boards dry faster after rain
● Allow water to drain through the deck surface
● Reduce the risk of mold, mildew, and rot
● Make cleaning and debris removal easier
Standard Deck Board Spacing Guidelines
There is no single spacing rule that applies to every deck. The correct gap depends on material type, moisture content, and installation conditions.
General Rule of Thumb
One eighth inch to three sixteenths inch spacing is typical for most decks once boards have acclimated.
Deck Board Spacing for Wood Decking
Dry or Seasoned Wood Deck Boards
If your boards are dry at the time of installation:
● Leave a three sixteenths inch gap between boards
● This spacing allows room for seasonal expansion while maintaining good drainage
Builders often use a sixteen penny nail or deck spacer to maintain consistent gaps during installation.
Wet or Green Wood Deck Boards
If boards are freshly treated or contain high moisture:
● Install boards tight together with no visible gap
● As the boards dry, they will naturally shrink and create spacing
Allowing wood to acclimate before installation produces the most consistent long term results.
Deck Board Spacing by Material
Redwood, Cedar, and Pressure Treated Lumber
● Expansion occurs primarily across the width of the board
● Spacing depends heavily on moisture content at installation
● Proper airflow is critical for long term durability
Hardwood Decking
● Dense hardwoods move less than softwoods
● Small, consistent gaps are still necessary for drainage and temperature changes
Composite Decking
● Composite boards expand and contract mainly with temperature, not moisture
● Spacing requirements vary by manufacturer
● Side gaps and end gaps may differ
Always follow the installation guidelines provided for your specific decking product.
How Climate Affects Deck Board Spacing
Environmental conditions influence how deck boards move after installation.
● Wet or coastal climates benefit from slightly wider gaps for drainage
● Hot, sunny areas require room for thermal expansion
● Shaded decks may retain moisture longer and need improved airflow
Considering local climate helps prevent spacing issues over time.
Tools That Help Maintain Consistent Deck Board Spacing
● Deck board spacers
● Hidden fastener systems
● Manufacturer approved clips
● Simple shims or nails for manual spacing
Consistent spacing improves both appearance and performance.
Common Deck Board Spacing Mistakes to Avoid
● Installing dry boards with no gap
● Over spacing boards, creating uncomfortable or unsafe gaps
● Ignoring manufacturer spacing guidelines
● Using inconsistent spacing tools
● Confusing deck board spacing with joist spacing
Avoiding these mistakes helps extend the life of your deck and reduces maintenance needs.
Deck Board Spacing Summary
● Dry wood boards require a three sixteenths inch gap
● Wet boards should be installed tight and spaced as they dry
● Composite boards must follow manufacturer instructions
● Climate and sun exposure matter
● Proper spacing improves drainage, durability, and appearance
Get Help With Decking Materials at OK Lumber
Choosing the right deck board spacing is only one part of building a durable, well performing deck. Selecting the right decking materials and accessories is just as important for long term results. OK Lumber carries a wide selection of decking and lumber products to support every stage of your project.
We supply:
● Redwood decking in multiple grades
● Hardwood decking including Ipe and Thermory
● Composite decking from Trex and TimberTech
● Pressure treated framing lumber
● Fasteners, spacers, and deck installation accessories
If you have questions about deck board spacing or need help selecting the right decking and lumber for your project, the team at OK Lumber is ready to help. Visit us or contact our team for guidance and material support for your next deck build.
