Siding Calculator
Estimate siding materials for exterior wall coverage. Works for vinyl, fiber cement, wood, and metal siding with waste factors.
Professional Siding Calculator
Industry-standard material calculations based on ASTM specifications
Project Information
Project Complexity
This determines the waste factor applied to calculations
Frequently Asked Questions
How is siding coverage calculated?
Siding coverage depends on material type and installation method. Vinyl siding: 1 square = 100 sq ft actual coverage. Fiber cement lap: varies by plank width (6-12 inches). Board and batten: calculate board coverage minus gap spacing. Manufacturers provide exposure rates per piece or per box.
Should I deduct windows and doors from siding calculations?
Yes, deduct all window and door openings from total wall area. However, add back 5-10% for trim, corners, and waste. Large windows and garage doors significantly reduce siding needs. Multiply gable areas by 0.5 to approximate triangular area, or use height × width ÷ 2 for accuracy.
How much waste factor for siding?
Standard installations need 10% waste for cuts, corners, and trim. Complex layouts with multiple corners, angles, or architectural details require 15% waste. Diagonal or decorative patterns need 15-20% waste. Fiber cement has higher waste (12-15%) due to brittleness requiring careful cuts per ASTM C1186.
How many squares of siding do I need?
Calculate total wall square footage (length × height for each wall), deduct openings, add waste factor, then divide by 100 to get squares. Example: 2,000 sq ft of walls minus 300 sq ft openings = 1,700 sq ft. With 10% waste: 1,870 sq ft = 18.7 squares (round up to 19 squares).
Industry Standards Referenced
ASTM D3679 - Rigid Poly(Vinyl Chloride) (PVC) Siding(ASTM D3679)
View StandardMaterial specifications and installation standards for vinyl siding including impact resistance, wind load ratings, expansion allowances, and fastening methods.
Key Requirements:
- •Expansion gaps: 1/4 to 1/2 inch at trim (vinyl expands/contracts with temperature)
- •Fastener placement: Center of slot, allow panel to move, don't overdrive
- •Nail penetration: Minimum 3/4 inch into solid wood or approved sheathing
- •Wind rating: Standard 110 mph, enhanced 160 mph in hurricane zones
- •Substrate: Flat, smooth surface required - OSB or plywood sheathing recommended
ASTM C1186 - Flat Fiber-Cement Siding(ASTM C1186)
View StandardSpecifications for fiber-cement siding products (HardiePlank, James Hardie) including composition, strength, moisture resistance, and installation requirements.
Key Requirements:
- •Nailing: Face nailing only (no blind nailing), corrosion-resistant nails required
- •Clearance: Minimum 6 inches from grade, 2 inches from horizontal surfaces
- •Joint treatment: All field-cut edges must be sealed (paint or caulk)
- •Fastener spacing: 16 inches maximum on studs 16 inches on-center
- •Substrate: Minimum 7/16-inch OSB or 1/2-inch plywood sheathing
IRC R703 - Exterior Covering(IRC 2021 Section R703)
View StandardBuilding code requirements for exterior wall coverings including water-resistive barriers, flashing, attachment specifications, and weather protection standards.
Key Requirements:
- •Water-resistive barrier: Required behind all siding (felt paper, house wrap, etc.)
- •Flashing: Required at all penetrations, windows, doors, and horizontal transitions
- •Clearance to grade: 6-inch minimum for wood siding, varies by material
- •Ventilation: Proper cavity ventilation prevents moisture accumulation
- •Fastening: Must penetrate studs or approved sheathing per manufacturer specs
Vinyl Siding Institute (VSI) Installation Manual(VSI Standards)
View StandardComprehensive installation guidelines from vinyl siding industry association. Covers proper handling, storage, fastening, and troubleshooting for vinyl siding installations.
Key Requirements:
- •Temperature considerations: Don't install below 40°F (vinyl becomes brittle)
- •Fastening: Leave 1/32-inch gap between nail head and panel for expansion
- •Starter strip: Critical for first course, must be level and straight
- •J-channel: Required at all windows, doors, and trim transitions
- •Accessories: Corners, trim, and accessories must match siding brand for fit
James Hardie Installation Guidelines(Manufacturer Specifications)
View StandardLeading fiber-cement manufacturer's installation requirements. Following these precisely is required for warranty coverage. Covers climate-specific installation methods.
Key Requirements:
- •Climate zones: Different installation for HZ5 (dry) vs HZ10 (wet) climates
- •Nailing: Blind nailing prohibited, face nailing only with approved fasteners
- •Joint spacing: 1/4-inch gaps required at all butt joints for caulking
- •Painting: Pre-primed boards must be painted within 180 days
- •Warranty: 30-year product warranty requires professional installation following manual
Standards Disclaimer: Standards and codes are subject to periodic updates. Always verify current requirements with local building authorities and professional engineers before beginning construction. Links provided are for reference only.
Want to Learn More?
Coverage calculations for vinyl, fiber cement, wood, and metal siding with ASTM installation specifications and waste factors.
Read the Siding Materials GuideHow to Use This Calculator
- Measure wall area: Input total square footage of exterior walls.
- Select siding type: Choose vinyl, fiber cement, wood, or metal.
- Subtract openings: Enter square footage of doors and windows.
- Review materials: See panels/boards, trim, and accessories needed.
Siding Coverage Standards
Vinyl siding: 1 square = 100 sq ft installed. Fiber cement 4x8 sheets: 32 sq ft per sheet. Add 10% waste for vertical, 15% for diagonal installation per ASTM D4756.