🏗️ Roof Truss Calculator
Calculate roof truss dimensions and requirements
Distance between supporting walls
Rise in inches per 12 inches of run
Typical: 16", 19.2", or 24" on center
Length of building perpendicular to trusses
How to Use This Calculator
Enter Span
Input the truss span in feet. This is the horizontal distance between the supporting walls or beams.
Enter Roof Pitch
Input the roof pitch in inches per 12 inches of run. For example, enter "6" for a 6/12 pitch.
Enter Truss Spacing and Building Length
Input truss spacing in inches (typically 16", 19.2", or 24") and building length in feet. Click "Calculate Roof Truss" to see results.
Formula
Rafter Length = √(Run² + Rise²)
Run = Span / 2, Rise = Run × (Pitch / 12)
Number of Trusses = (Building Length / Truss Spacing) + 1
Roof Area = 2 × Rafter Length × Building Length
Example: 30 ft span, 6/12 pitch, 24" spacing, 40 ft length
Step 1: Run = 30 / 2 = 15 feet
Step 2: Rise = 15 × (6/12) = 7.5 feet
Step 3: Rafter length = √(15² + 7.5²) = 16.77 feet
Step 4: Number of trusses = (40 / 2) + 1 = 21 trusses
Step 5: Roof area = 2 × 16.77 × 40 = 1,342 sq ft
About Roof Truss Calculator
The Roof Truss Calculator is an essential tool for contractors, carpenters, architects, and builders who need to calculate roof truss dimensions and requirements. This calculator eliminates guesswork by providing precise calculations for roof trusses based on span, pitch, spacing, and building length, helping you estimate materials and plan construction accurately.
When to Use This Calculator
- Truss Planning: Calculate number of trusses needed for roof construction
- Material Estimation: Estimate trusses, roofing materials, and components needed
- Rafter Sizing: Determine rafter lengths and roof dimensions
- Project Planning: Plan roof truss projects with accurate dimensions
- Cost Estimation: Calculate material costs based on truss requirements
Why Use Our Calculator?
- ✅ Accurate Calculations: Precise truss calculations using standard geometric formulas
- ✅ Multiple Dimensions: Calculates rafter lengths, roof height, area, and number of trusses
- ✅ Load Estimates: Provides load estimates based on building type
- ✅ Time Savings: Instant calculations eliminate manual math
- ✅ Easy to Use: Simple input fields for span, pitch, spacing, and length
Understanding Roof Trusses
Truss Definition: A roof truss is a prefabricated structural framework used to support the roof. Trusses consist of triangular frames made of wood or metal members connected at joints. They distribute roof loads efficiently to supporting walls.
Truss Spacing: Typical truss spacing is 16 inches, 19.2 inches, or 24 inches on center. Closer spacing provides stronger support but requires more trusses. Spacing depends on roof loads, span, and building codes.
Load Requirements: Roof trusses must support dead loads (roofing materials) and live loads (snow, wind, maintenance). Residential buildings typically need 20 psf live load, while commercial buildings need 30 psf or more.
Important Notes
- Engineering Required: Actual truss design requires structural engineering. This calculator provides estimates only.
- Consult Engineers: For all truss installations, consult a structural engineer or truss manufacturer
- Local Codes: Verify truss spacing and loads with local building codes
- Manufacturer Specifications: Use actual truss manufacturer specifications for construction
- Professional Installation: Trusses require professional installation for safety
Frequently Asked Questions
What is a roof truss?
A roof truss is a prefabricated structural framework used to support the roof. Trusses consist of triangular frames made of wood or metal members connected at joints. They distribute roof loads efficiently to supporting walls.
How many trusses do I need?
Number of trusses = (Building Length / Truss Spacing) + 1. For example, a 40-foot building with 24-inch (2-foot) spacing: (40 / 2) + 1 = 21 trusses. The calculator performs this automatically.
What is typical truss spacing?
Typical truss spacing is 16 inches, 19.2 inches, or 24 inches on center. Closer spacing provides stronger support but requires more trusses. Spacing depends on roof loads, span, and building codes. The calculator works with any spacing.
Can I design trusses myself?
No. Truss design requires structural engineering. This calculator provides estimates for planning purposes only. Always consult a structural engineer or truss manufacturer for actual truss design and specifications.
What loads do trusses need to support?
Trusses must support dead loads (roofing materials, typically 10 psf) and live loads (snow, wind, maintenance). Residential buildings typically need 20 psf live load, commercial buildings need 30 psf, and heavy-duty buildings need 40+ psf.