Deck Board Spacing Calculator — Calculate Proper Deck Board Gaps

Deck Board Spacing Calculator

Calculate the perfect spacing between deck boards for optimal drainage, expansion, and appearance. Determine proper gaps based on board width, wood type, and climate conditions.

Step 1: Deck Specifications

Understanding Deck Board Spacing

Proper spacing allows for wood expansion, drainage, and prevents buckling. Typically 1/8″ to 1/4″ gap is recommended, depending on wood type and moisture content.

Step 2: Wood & Climate Conditions

15%
60%

About Wood Expansion

Wood expands and contracts with changes in moisture. Higher humidity climates require slightly larger gaps. Composite decking requires smaller gaps (1/8″) while natural wood needs more space (1/4″).

Deck Spacing Results

Summary
Wood Comparison
Breakdown

Recommended Gap Between Boards

0.25″
For 7.25″ cedar boards at 15% moisture
Number of Boards
20
Total Gap Space
4.75″
Board Width
7.25″
Wood Type
Cedar

Wood Type Spacing Comparison

Wood Type Recommended Gap Expansion Rate Moisture Sensitivity

Spacing Process Breakdown

Spacing Calculation Formula

Gap = Base Gap + (Moisture Factor × Humidity Factor)

Base gap varies by wood type. Moisture factor accounts for wood’s current moisture content. Humidity factor adjusts for local climate conditions.

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