Construction Tool
Truss Calculator
Calculate roof truss dimensions, loads, and costs. Supports 8 truss types, 9 roof pitches, and multiple loading conditions for residential and commercial projects.
8 Truss Types-Rise & Rafter Length-Load Analysis-Cost Estimate
Truss Calculator
6.00
Rise (ft)
13.42
Rafter Length (ft)
1440
Total Load/Truss (lbs)
720
Reaction Force (lbs)
Truss typeFink
Pitch6/12 (26.6 deg)
Top chord total26.83 ft
Bottom chord24.00 ft
Tributary width2.00 ft
Truss Type Comparison
| Truss Type | Max Span | Cost Range | Best For |
|---|---|---|---|
| King Post | 24 ft | $75-$125 | Sheds, small additions |
| Queen Post | 36 ft | $100-$175 | Medium residential |
| Fink (W) | 40 ft | $100-$200 | Most common residential |
| Howe | 60 ft | $150-$300 | Wider residential, light commercial |
| Pratt | 80 ft | $200-$400 | Commercial, long spans |
| Warren | 100 ft | $250-$500 | Bridges, large commercial |
| Scissor | 40 ft | $175-$350 | Cathedral/vaulted ceilings |
| Gambrel | 36 ft | $150-$300 | Barns, bonus room above |
Frequently Asked Questions
What is a roof truss?⌄
A roof truss is a pre-engineered structural framework of triangles that supports the roof. Trusses are manufactured off-site and lifted into place, replacing traditional stick-built rafters. They span the full width of the building without interior load-bearing walls.
How much does a roof truss cost?⌄
Common residential trusses (Fink, 24-32 ft span) cost $75-$250 each depending on span, pitch, and region. Specialty trusses (scissor, gambrel) cost $150-$400+. Installation adds $75-$150 per truss for crane and labor.
What is the most common residential truss type?⌄
The Fink truss (W-pattern webbing) is most common for residential construction. It efficiently handles spans up to 40 feet and works with most roof pitches. It is the most cost-effective for standard homes.
How far apart should roof trusses be spaced?⌄
Standard residential spacing is 24 inches on center (OC). 16-inch OC spacing is used for higher load requirements (heavy snow, tile roofing). Commercial buildings may use 48-inch OC with heavier trusses.
What roof pitch is most common?⌄
4/12 to 6/12 pitch is most common for residential roofs. 4/12 is the minimum for standard shingles. 6/12 provides good water shedding and attic space. 12/12 (45 degrees) is steep and usually decorative.
How do I calculate the rise from roof pitch?⌄
Rise = (Span / 2) x pitch ratio. For a 24 ft span with 6/12 pitch: Rise = 12 x 0.5 = 6 ft. The rafter length = sqrt((span/2)^2 + rise^2) = sqrt(144 + 36) = sqrt(180) = 13.4 ft.
What is the dead load vs live load on a truss?⌄
Dead load = permanent weight (roofing material, sheathing, insulation). Typically 10-20 psf. Live load = temporary forces (snow, workers, wind). Typically 20-40 psf. Total design load = dead + live.
Can I modify or cut a roof truss?⌄
Never cut, drill, or modify a truss without an engineer's approval. Trusses are engineered as complete systems. Cutting one member can cause catastrophic failure. If modifications are needed, consult a structural engineer.