Clapboard and Lap Board Siding Calculator
Calculate clapboard or lap siding boards, courses, linear feet, and cost. Choose from 5 board materials with exposure, overlap, and gable area support.
π Clapboard & Lap Siding Calculator
WALL
COURSES
MATERIAL
COST
π‘ Clapboard & Lap Siding Estimation
Clapboard (also called lap, bevel, or weatherboard siding) is one of the most iconic American home exterior styles, dating back to Colonial New England. Modern clapboard siding is available in natural wood, fiber cement, engineered wood, and composite materials β each with different exposure, overlap, and cost characteristics.
The calculator above supports 5 board materials with auto-filled pricing, adjustable board width and overlap, multiple board lengths, gable area input, individual window/door counts, and outputs courses, boards, linear feet, and cost.
Compare siding with our siding material calculator. For vinyl, see our vinyl siding calculator. Measure wall area with our square footage calculator.
Board Material Comparison
| Material | Common Width | Exposure | Cost/lin ft | Lifespan |
|---|---|---|---|---|
| Western Red Cedar | 6" | 4.75" | $2.00β$3.50 | 30β50 yrs |
| Fiber Cement (HardiePlank) | 8.25" | 7" | $1.50β$2.50 | 30β50 yrs |
| Pine / Spruce (primed) | 6" | 4.75" | $0.80β$1.60 | 15β25 yrs |
| Engineered Wood (LP SmartSide) | 8" | 6.75" | $1.20β$2.00 | 25β50 yrs |
| Composite / PVC | 8" | 6.75" | $2.50β$4.00 | 30β50+ yrs |
Most popular: Fiber cement (HardiePlank) dominates the US lap siding market β it's fire-resistant, termite-proof, and mimics the look of real wood. Western Red Cedar remains the premium natural-wood choice for its dimensional stability and natural decay resistance.
Understanding Exposure and Overlap
Board width = the full width of the siding plank. Overlap = the hidden portion covered by the board above (typically 1"β1Β½"). Exposure = the visible portion = board width β overlap.
- 6" board, 1.25" overlap β 4.75" exposure (standard for cedar)
- 8" board, 1.25" overlap β 6.75" exposure (standard for fiber cement)
- 10" board, 1.5" overlap β 8.5" exposure (wider profile)
Important: Minimum overlap of 1" is required for water resistance. In high-wind zones, 1.5" or more is recommended. Always follow manufacturer specifications for your climate.
Step-by-Step Clapboard Estimation
Step 1: Calculate Courses (Rows)
Convert wall height to inches. Divide by the exposure in inches. Round up to the nearest whole number.
Example: 9 ft wall = 108 in Γ· 4.75" exposure = 22.7 β 23 courses
Step 2: Calculate Boards per Course
Divide wall length by board length. Round up.
Example: 40 ft wall Γ· 12 ft boards = 3.33 β 4 boards per course
Step 3: Total Boards and Linear Feet
Boards = courses Γ boards per course. Linear feet = total boards Γ board length.
Example: 23 courses Γ 4 boards = 92 boards = 1,104 lin ft
Step 4: Add Waste
Add 10% for rectangular walls. Add 15β20% for gable walls (angle cuts produce more waste). Add 5% extra if boards have knots or defects to cull.
Gable Walls
Gable walls are triangular. To estimate boards: calculate courses using the same exposure, multiply by the gable width, then divide by 2 (since each successive course gets shorter). Add 15β20% waste for the angle cuts.
Example: A 30 ft Γ 8 ft gable at 4.75" exposure: 21 courses Γ 30 ft Γ· 2 = 315 lin ft + 20% waste = 378 lin ft.
Common Board Sizes
| Nominal Width | Actual Width | Typical Exposure | Lengths Available |
|---|---|---|---|
| 4" | 3.5" | 2.25"β2.5" | 8', 10', 12' |
| 6" | 5.5" | 4.25"β4.75" | 8', 10', 12', 16' |
| 8" | 7.25"β8.25" | 6"β7" | 8', 10', 12', 16' |
| 10" | 9.25" | 7.75"β8.5" | 8', 12', 16' |
| 12" | 11.25" | 9.75"β10.5" | 8', 12', 16' |
2025 US Clapboard Cost Guide
| Material | Material/lin ft | Installed/sq ft | 1,200 sq ft Home |
|---|---|---|---|
| Pine (primed) | $0.80β$1.60 | $4β$7 | $4,800β$8,400 |
| Fiber Cement | $1.50β$2.50 | $6β$10 | $7,200β$12,000 |
| Engineered Wood | $1.20β$2.00 | $5β$9 | $6,000β$10,800 |
| Cedar | $2.00β$3.50 | $8β$14 | $9,600β$16,800 |
| Composite / PVC | $2.50β$4.00 | $10β$16 | $12,000β$19,200 |
Labor: Professional installation typically runs $3β$6/sq ft for clapboard siding. Total installed cost ranges from $7β$20/sq ft depending on material and home complexity.