Gambrel Roof Truss Calculator
* Estimates for budgeting. Does not include installation labor, purlins, or sheathing. Get quotes from truss manufacturers for engineered specifications.
Disclaimer: Estimates are for budgeting purposes only. Actual costs vary by location, contractor, material availability, and project complexity. Always get professional quotes for exact pricing.
Gambrel Roof Truss Pricing
| Truss Type | Price / Foot | Best For |
|---|---|---|
| Prefab Gambrel | $4 – $8 | 16–36 ft barns, large sheds |
| Custom Engineered | $8 – $15 | 36+ ft spans, heavy loads |
| Site-Built (DIY) | $3 – $6 | Small sheds under 16 ft |
Truss Count by Building Size
| Building Size | 16" Spacing | 24" Spacing |
|---|---|---|
| 12×16 shed | 13 trusses | 9 trusses |
| 16×24 shed | 19 trusses | 13 trusses |
| 24×32 barn | 25 trusses | 17 trusses |
| 36×48 barn | 37 trusses | 25 trusses |
* Formula: (length in inches ÷ spacing) + 1. Includes end trusses.
How We Calculate
Our gambrel roof truss calculator estimates costs based on building dimensions, truss spacing, and truss type. Prefab trusses are priced per foot of span, while custom engineered trusses cost more for complex designs.
How the math works: Truss count = (building length ÷ spacing) + 1. Material cost = truss count × span × price per foot. The +1 accounts for end trusses. Delivery is a flat fee per shipment.
Truss Type Comparison
Prefab Gambrel Trusses ($4–$8/ft) are factory-built with precision jigs and include engineer stamps. Most cost-effective for 16–36 ft spans. Lead time is 2–4 weeks. Standard for residential barns and large sheds.
Custom Engineered Trusses ($8–$15/ft) are designed for unique spans, heavy loads, or complex geometry. Required for buildings over 36 ft wide, commercial barns, or high wind/snow zones. Include sealed engineer drawings. Lead time 4–8 weeks.
Site-Built Trusses ($3–$6/ft) use dimensional lumber (2×4, 2×6) assembled on-site with gusset plates. Only suitable for small sheds under 16 ft wide. Not permitted for habitable structures or buildings requiring permits. No engineering, so homeowner assumes liability.
Gambrel Roof Advantages
Maximum Usable Space: Gambrel roofs provide 50–75% more loft area than gable roofs of the same footprint. A 24×32 barn gains 400–600 sq ft of usable loft space with gambrel vs gable trusses.
Classic Aesthetic: Gambrel roofs evoke traditional barn architecture. Popular for country homes, barns, and sheds in rural or agricultural settings.
Cost vs Second Story: Adding a gambrel roof loft costs 60–70% less than building a full second story with conventional framing.
Additional Costs
Our estimates cover trusses only. Not included: installation labor ($2–$4/sq ft of roof), purlins/bracing ($200–$600 for 24×32 barn), sheathing ($1–$2/sq ft for OSB), roofing material ($2–$8/sq ft for metal or shingles), and crane rental ($300–$600 for large trusses over 30 ft).
Data Sources
Pricing from truss manufacturers, HomeAdvisor, and Angi contractor estimates. Engineering requirements per IRC 2021 and IBC. We review and update regularly.
Last updated: 2026-02-09
Frequently Asked Questions
What is a gambrel roof truss? +
A gambrel roof truss has two slopes on each side — a steep lower slope and a shallow upper slope. This design maximizes attic or loft space, commonly seen on barns, sheds, and Dutch Colonial homes. Gambrel trusses provide more headroom than standard gable trusses while using less material than a full second story.
How much do gambrel roof trusses cost? +
Gambrel roof trusses cost $4–$8 per foot of span for prefab trusses, $8–$15/ft for custom engineered trusses, and $3–$6/ft for site-built DIY trusses. A 24-ft span barn with 16 trusses costs $1,500–$3,000 for prefab trusses. Includes materials only — add $2–$4/sq ft of roof for installation labor.
How far apart should gambrel trusses be spaced? +
Standard spacing is 24 inches on center for most barns and sheds. Use 16" spacing for heavy snow loads (50+ psf) or metal roofing without purlins. Pole barns can use 48" spacing if designed with heavier trusses and structural purlins. Closer spacing increases cost but provides a stronger roof.
Can I build gambrel trusses myself? +
Yes, for small sheds (12×16 or smaller) you can build gambrel trusses on-site using 2×4 or 2×6 lumber and gusset plates. DIY saves 40–50% vs prefab trusses. For structures over 16 ft wide or habitable buildings, use engineered prefab trusses — DIY trusses lack engineer stamps required by code and may fail under snow loads.
What is the best pitch for a gambrel roof? +
Classic gambrel pitch: lower slope at 60° (21/12 pitch), upper slope at 30° (7/12 pitch). This maximizes interior space. Modern barns often use 50° lower (14/12) and 20° upper (4/12) for easier construction. Steeper lower slopes provide more headroom but require taller walls. Upper slope should be 4/12 or steeper for proper water drainage.
How do I calculate the number of trusses needed? +
Formula: (building length in inches ÷ truss spacing on center) + 1. For a 32-ft (384") barn with 24" spacing: 384 ÷ 24 = 16 spaces, plus 1 = 17 trusses. The +1 accounts for trusses at both ends. Add 1–2 extra trusses for gable overhangs if desired.
Are gambrel roofs more expensive than gable roofs? +
Gambrel roofs cost 10–20% more than gable roofs due to complex truss geometry and extra materials. Prefab gambrel trusses cost $4–$8/ft vs $2–$5/ft for gable trusses. However, gambrel roofs eliminate the need for a full second story, saving $15,000–$40,000 compared to adding a second floor for equivalent space.
Do gambrel roof trusses require engineering? +
Yes, gambrel trusses for buildings over 16 ft wide or habitable structures require engineered designs with sealed drawings per IRC. Engineers calculate loads, member sizes, and connections. Truss manufacturers provide engineered plans with prefab trusses. DIY site-built trusses for small non-habitable sheds (under 200 sq ft) typically don't require permits or engineering in most jurisdictions.
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