Outside wall to outside wall
Along the ridge line
Typical: 12-24 inches
Last updated: 2026-03-18
How to Estimate Roof Trusses for Any Building
Trusses changed residential construction. Instead of cutting and assembling rafters one board at a time on the roof, a crane drops factory-built trusses into place in hours. I've watched a crew set 40 trusses on a house before lunch. That speed matters when you're bidding jobs, because labor is where the money goes.
The math for truss count is straightforward. Divide the building length by the on-center spacing and add one. But the cost side gets more involved. Span, truss type, pitch, and your location all affect the per-truss price. Delivery and crane costs add up fast too. This calculator handles all of it so you can get a realistic budget number before you call the truss plant.
Inputs you'll need
- Building span - Outside wall to outside wall (feet). This is the truss span.
- Building length - Ridge direction measurement (feet)
- Roof pitch - Rise per 12 inches of run (e.g. 6/12)
- Truss spacing - 24" OC (standard) or 16" OC (heavy loads)
- Truss type - Common, attic, scissors, or mono
- Eave overhang - Horizontal overhang past the wall (inches)
2026 Truss Pricing by Span
Common truss, material only. Add delivery + crane for installed cost.
| Span Range | Price Per Truss | Typical Use |
|---|---|---|
| Up to 20 ft | $65 - $130 | Sheds, carports, small additions |
| 20 - 28 ft | $90 - $175 | 1-car garages, small homes |
| 28 - 36 ft | $140 - $270 | Standard homes, 2-car garages |
| 36 - 44 ft | $200 - $380 | Large homes, workshops |
| 44 - 52 ft | $280 - $480 | Large residential, light commercial |
| 52 - 60 ft | $350 - $600 | Commercial, agricultural |
Truss Type Price Multipliers
| Truss Type | Price vs Common | Best For |
|---|---|---|
| Common | 1.0x (baseline) | Standard gable roofs, most residential |
| Scissors | 1.3x | Vaulted ceilings, great rooms |
| Attic / Room-in | 1.4x | Usable attic space, bonus rooms |
| Mono (lean-to) | 0.75x | Additions, shed roofs, porches |
Worked examples
Example A: 28x40-ft garage, 6/12 pitch, common trusses at 24" OC
- Field trusses = (40 / 2) + 1 = 21
- Gable end trusses = 2
- Total = 23 trusses
- Per-truss cost (28 ft span): $90 - $175 each
- Truss material: 21 x ($90-$175) + 2 x ($54-$105) = $1,998 - $3,885
- Delivery: $250 - $800
- Crane + setting: $115 - $230
- Hardware: $69 - $138
- Total installed: $2,432 - $5,053
Example B: 36x60-ft home, 8/12 pitch, common trusses at 24" OC
- Field trusses = (60 / 2) + 1 = 31. Gable ends = 2. Total = 33
- Per-truss cost (36 ft span): $140 - $270 each
- Truss material: 31 x ($140-$270) + 2 x ($84-$162) = $4,508 - $8,694
- Total installed with delivery/crane/hardware: $5,173 - $10,024
Example C: 24x30-ft addition, scissors trusses at 24" OC
- Field trusses = (30 / 2) + 1 = 16. Gable ends = 2. Total = 18
- Scissors multiplier: 1.3x common price
- Per-truss cost: $90 x 1.3 = $117 to $175 x 1.3 = $228
- Total installed: approximately $2,450 - $5,000
Already have the truss package? Use the roof sheathing calculator to figure out how many sheets of OSB you need, or the shingle calculator to estimate roofing material. Comparing trusses to stick-framing? Check the rafter calculator.
Trusses vs. rafters: when to use each
| Factor | Trusses | Rafters |
|---|---|---|
| Install speed | Fast (crane sets 20-30/hr) | Slow (cut and fit each one) |
| Cost per sq ft | $3 - $5 installed | $3 - $8 installed |
| Attic space | Filled with web members | Open, usable space |
| Max span | 60+ ft without bearing walls | 26 ft max for 2x12 |
| Complex shapes | Limited flexibility | Any shape possible |
| Lead time | 2-4 weeks to order | Build same day |
What to know before you order
- Get sealed engineering drawings. Truss manufacturers produce stamped plans with bearing points, bracing requirements, and connection details. Your building inspector will require these. Do not install trusses without them.
- Verify your delivery access. Trusses ship on flatbed trucks. A 40-ft truss package needs a clear, straight path to the building site. Tight lots in older neighborhoods can be a problem. Ask the manufacturer about delivery feasibility before you order.
- Plan your bracing before the crane shows up. Trusses are unstable until they are braced. You need temporary lateral bracing every 8-10 ft and permanent diagonal bracing per the engineer's plan. Have the bracing lumber and a plan ready before the crane arrives. I've seen guys scramble to brace trusses while the crane operator is billing by the hour. That gets expensive.
- Never modify a truss. Do not cut, drill, or remove any web member without a written approval from the truss engineer. One missing web can compromise the entire roof structure. If you need to run ductwork, plumbing, or wiring through trusses, specify that during the design phase.
- Order 1-2 extras. Shipping damage happens. Having a spare on-site saves a week of waiting for a replacement. The cost of one extra truss is nothing compared to a crew standing idle.
Common mistakes that cost money
- Ordering before the foundation is complete. If the foundation dimensions are off by even half an inch, your trusses may not fit. Wait until you can verify the actual span before placing the order.
- Ignoring wind uplift requirements. High-wind zones require hurricane clips or straps at every truss-to-wall connection. That is code, not optional. Factor in the hardware cost and labor to install them.
- Forgetting the bearing point locations. Trusses need support at specific points. If you have interior bearing walls that do not line up with the truss design, something has to change. Coordinate with the truss engineer early.
- Storing trusses flat on the ground. Trusses should be stored upright and braced, not stacked flat. Laying them flat can warp the bottom chord and weaken connections. If they sit on-site for more than a few days, keep them off the ground and covered.
- Undersizing for the load. Standard trusses handle 20 psf live load. If you are in heavy snow country (40+ psf) or planning a tile roof, the truss design and price change significantly. Tell the manufacturer your loads upfront.
How to Use This Calculator
Enter your building dimensions
Input the building span (outside wall to outside wall) and the building length along the ridge. Use your plans or measure from the outside edges of the top plates.
Select roof pitch and truss spacing
Choose the roof pitch (rise over 12 inches of run) and truss spacing. Most residential truss roofs use 24" on center. Switch to 16" OC for heavy snow loads or tile roofing.
Pick your truss type
Choose from common (standard gable), attic/room-in (open center for usable space), scissors (vaulted ceiling), or mono (single slope lean-to). Type affects both cost and structural capacity.
Review truss count and costs
Get the total truss count, per-truss pricing, delivery, crane and setting labor, hardware, and total installed cost. Adjust your location for regional pricing differences.
Truss Count & Cost Formulas
Trusses = (Building Length ÷ Spacing) + 1 + Gable Ends
Truss Height = (Span ÷ 2) × (Pitch ÷ 12)
Roof Area = 2 × (Half Span + Overhang) × Pitch Factor × Adjusted Length
Total Cost = (Field Trusses × Per-Truss Price) + Gable Ends + Delivery + Crane + HardwareWhere:
- Building Length
- = Distance along the ridge direction (feet)
- Spacing
- = On-center distance between trusses (24" or 16")
- Span
- = Wall-to-wall distance that the truss bridges (feet)
- Pitch
- = Roof slope as rise per 12 inches of run (e.g. 6/12)
- Pitch Factor
- = sqrt(1 + (pitch/12)^2) - converts horizontal to slope distance
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Frequently Asked Questions
How many trusses do I need for my roof?
Divide your building length (in feet) by the on-center spacing (in feet), then add 1. At 24" OC (2 ft), a 40-ft building needs (40/2) + 1 = 21 field trusses. Add 2 gable-end trusses (flat, non-structural) for a total of 23. At 16" OC, the same building needs 31 field trusses plus 2 gable ends = 33 total.
How much does a roof truss cost in 2026?
Truss prices depend mainly on span. For a standard common truss in 2026: up to 20 ft span: $65-$130, 20-28 ft: $90-$175, 28-36 ft: $140-$270, 36-44 ft: $200-$380. Attic trusses run about 40% more and scissors trusses about 30% more than common. These are material-only prices. Add delivery ($250-$800) and crane/setting labor ($5-$10/truss) for installed cost.
What is the difference between trusses and rafters?
Trusses are pre-engineered, factory-built triangular frames with web members connecting the top and bottom chords. Rafters are individual boards cut and assembled on-site. Trusses go up faster (a crane can set 20-30 trusses in a few hours), span longer distances without interior bearing walls, and cost $3-$5/sq ft of roof plan area installed. Rafters cost $3-$8/sq ft but give you usable attic space since there are no web members filling the cavity. Trusses are the standard for production homes. Rafters are better for complex roof shapes or when you want a finished attic.
How far apart should roof trusses be spaced?
24 inches on center is the standard spacing for most residential truss roofs. This works for asphalt shingles with standard snow loads. Use 16" OC when you have heavy snow loads (40+ psf ground snow), tile or slate roofing, or need extra strength for long spans. Your truss engineer will specify the spacing on the sealed drawings.
Do I need a crane to set trusses?
For spans under 20 ft, a small crew can hand-set trusses. For anything larger, you need a crane or boom truck. A 28-ft common truss weighs about 60 lbs, which is manageable for two people, but lifting it 8-10 ft up to the top plates safely requires equipment. Most truss packages for homes and garages are crane-set. Budget $200-$500 for a half-day crane rental, or ask if the truss supplier includes setting in their delivery price.
What truss type should I use?
Common trusses work for 90% of residential gable roofs. They are the cheapest and strongest per dollar. Attic trusses (room-in) create usable space inside the roof but cost 30-40% more and have span limitations (typically max 60 ft). Scissors trusses give you a vaulted ceiling inside, popular for great rooms and open floor plans. Mono trusses are single-slope, used for lean-to additions and shed-style roofs. Your truss manufacturer will engineer the design once you give them the building dimensions and loads.
How long does it take to get trusses delivered?
Standard lead times are 2-4 weeks from order to delivery. During peak building season (spring/summer), lead times can stretch to 6-8 weeks. Rush orders may be available for an upcharge. Order trusses as soon as your foundation is poured so they arrive when framing starts. Verify the delivery route - a semi truck hauling 60-ft trusses needs a clear path to the site with no tight turns or low wires.
What are gable end trusses?
Gable end trusses are flat, non-structural trusses installed at each end of a gable roof. They have vertical web members instead of diagonal ones and provide the surface for sheathing and siding at the gable ends. They typically cost 30-40% less than standard field trusses since they carry no roof load. Most buildings need 2 gable end trusses (one at each end). On a hip roof, gable end trusses are replaced by step-down hip trusses.
How much weight can a roof truss hold?
Trusses are engineered for specific loads. A typical residential truss is designed for 20 psf live load + 10 psf dead load on the top chord (roof) and 10 psf on the bottom chord (ceiling). Heavy snow areas may require 40-60 psf top chord loads. Never store heavy materials on trusses that were not designed for it. Do not cut, drill, or modify trusses without an engineer's approval - removing even one web member can cause a collapse.
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