Wood Siding Calculator

About the Wood Siding Calculator

Wood siding remains the gold standard for natural beauty and curb appeal. From classic New England clapboard to modern shiplap, wood siding comes in many profiles, species, and grades. Calculating material quantities requires knowing the coverage rate for each profile, which accounts for overlap (lap siding) or tongue loss (tongue-and-groove).

This calculator determines the number of boards (in linear feet or board feet) needed based on your net siding area, the board's nominal width, and the actual exposure after accounting for the siding profile's overlap. Different profiles have different overlap losses: lap/bevel siding loses 1–1.5" per course to overlap, while tongue-and-groove loses the tongue width (typically 3/8–1/2").

Wood siding is typically ordered in random lengths (8–16 ft) or specific lengths. The calculator estimates linear feet, which your supplier can convert to bundles or board feet as needed.

When This Page Helps

Wood siding has significant overlap/waste that varies by profile. This calculator accounts for the specific profile's exposure to prevent under-ordering, which can mean weeks of delay for specialty wood species.

How to Use the Inputs

1. Enter the net siding area.
2. Enter the nominal board width.
3. Enter the exposure (visible face after overlap or tongue loss).
4. Enter the average board length available.
5. Enter a waste factor (12–18% for wood).
6. Review the board count and total linear feet.

Example Calculation

Tips & Best Practices

• Cedar and redwood are the most popular species for their natural rot and insect resistance.
• Back-prime (seal the back side) all wood siding before installation to prevent cupping and moisture damage.
• Acclimate wood siding on-site for 5–7 days before installation to match local moisture content.
• Use stainless steel fasteners with natural wood — galvanized nails can cause staining on cedar and redwood.
• Plan for 15–18% waste with random-length boards (higher than vinyl or fiber cement due to knot avoidance and length matching).
• Consider pre-staining or pre-painting before installation for full coverage of all surfaces.

Wood Siding Profiles

Common profiles include: Bevel/Clapboard (horizontal lap), Shiplap (horizontal or vertical with rabbeted edges), Tongue-and-Groove (interlocking), Channel Rustic (horizontal with a shadow gap), and Board-and-Batten (vertical). Each profile has a different exposure calculation.

Species Selection

Western Red Cedar is the premium choice for its natural durability, straight grain, and light weight. Redwood offers similar properties with a richer color. Cypress is excellent in humid climates. Douglas Fir and Pine are more affordable but require more frequent maintenance and better surface protection.

Moisture Management

Wood siding must always be installed over a weather-resistant barrier (house wrap or felt paper). Allow 1/4" air gap between the barrier and siding back with furring strips (rain screen method) for optimal moisture management, especially in wet climates.

Frequently Asked Questions

• What is the difference between clapboard and bevel siding?

  Clapboard (or lap) siding is a board that tapers from thick at the bottom to thin at the top. Bevel siding is similar but milled with precise taper and smoother surfaces. Both are installed horizontally with the thick edge at the bottom, overlapping the board below.

• How much overlap does wood lap siding need?

  A minimum of 1 inch overlap, though 1.25–1.5 inches is standard. The overlap ensures water cannot be driven behind the siding by wind. Building codes typically specify minimum 1" overlap for horizontal lap siding.

• How is tongue-and-groove different?

  T&G siding has a tongue on one edge and a groove on the other. The boards interlock without visible overlap. Coverage is calculated by subtracting the tongue width from the nominal board width. T&G can be installed horizontally, vertically, or diagonally.

• What grade of wood should I use for siding?

  Clear or Select grade has no knots and provides the best appearance. #2 Common has small, tight knots and is more affordable. For painted siding, #2 is often sufficient. For stained or natural finishes, Clear grade shows the best grain.

• How long does wood siding last?

  Well-maintained wood siding lasts 30–60+ years. Cedar and redwood can last 50+ years if kept painted or stained. Pine and fir siding lasts 20–30 years with regular maintenance. The key is preventing moisture from penetrating behind or into the wood.

• Should I use wood or fiber cement siding?

  Wood offers natural beauty and easier on-site modification. Fiber cement offers better fire resistance, rot resistance, and lower maintenance. Wood costs more in long-term maintenance but less in initial material cost. Fiber cement costs more installed but requires less upkeep over its lifetime.