Types of Roof Trusses: A Complete Guide to Designs and Uses

Roof trusses are prefabricated structural frameworks that shape and support roofing systems, offering strength, economy, and design flexibility. This guide explains the most common types of roof trusses, their best uses, span capabilities, advantages, and design considerations for residential and commercial projects in the United States.

Truss Type	Typical Use	Span Range
King Post	Small residential roofs, porches	Up to ~30 ft
Queen Post	Medium spans, simple attics	25–45 ft
Fink	Common house roofs	Up to 60 ft
Howe/Pratt	Heavy loads, industrial	Medium to large spans
Scissor	Cathedral ceilings	Medium spans
Gambrel	Barns, extra attic space	Variable

What A Roof Truss Does And Why Type Matters

A roof truss Transfers Loads From The Roof Deck To Exterior Walls Using Triangular Geometry For Stability. Selecting The Right Type Affects Attic Space, Cost, Construction Speed, Thermal Performance, And Aesthetic Options.

Choosing The appropriate truss type improves structural efficiency, reduces material waste, and can simplify HVAC and insulation planning.

Common Truss Types And Their Characteristics

King Post Truss

The King Post Truss Is The Simplest Truss With A Central Vertical Post (King Post) Connecting The Ridge Beam To The Tie Beam. It Is Ideal For Short Spans And Traditional Appearances.

Best For Small Homes, Porches, And Historic Restorations; Economical And Easy To Fabricate.

Queen Post Truss

The Queen Post Uses Two Vertical Posts With A Straining Beam Between Them, Allowing Longer Spans Than The King Post While Maintaining A Simple Profile.

Useful When Extra Headroom Or An Open Attic Is Desired For Spans Up To About 45 Feet.

Fink Truss

The Fink Truss Features A W-Shaped Web Pattern And Is The Most Widely Used Truss For Residential Construction Because It Optimizes Material Use For Common Roof Pitches.

Offers Efficient Load Distribution For Typical Roofs, Cost-Effective For Spans Up To Approximately 60 Feet.

Pratt Truss

The Pratt Truss Has Diagonals That Slope Toward The Center With Vertical Web Members In Tension; Adapted From Bridge Engineering, It Works Well For Metal And Timber Roofs Carrying Heavy Loads.

Preferred For Long, Straight Runs With Concentrated Loads; Often Used In Industrial Buildings.

Howe Truss

The Howe Truss Is The Inverse Of Pratt: Diagonals Slope Away From The Center, Putting Diagonals In Compression And Verticals In Tension. It Handles Heavy Roof Loads Well.

Common For Heavy Timber Or Engineered Lumber Roofs And Long Spans Where Compression Members Are Robust.

Scissor Truss

Scissor Trusses Cross The Bottom Chords, Creating A Vaulted Or Cathedral Interior Ceiling Without The Need For Additional Support, While The Top Chords Form The Roof Pitch.

Ideal For Creating Open Interiors And Architectural Interest While Maintaining Structural Efficiency.

Gambrel Truss

The Gambrel Shape Has Two Different Roof Slopes On Each Side, Maximizing Upper-Level Space Often Seen In Barns And Dutch Colonial Homes.

Provides Substantial Attic Or Loft Area; Suited For Buildings Needing Extra Storage Or Living Space Under The Roof.

Attic/Storage Truss

Attic Or Storage Trusses Incorporate A Full-Depth Room-Sized Space Between The Bottom Chords, Turning The Roof System Into Usable Square Footage For Bedrooms Or Storage.

Efficient Way To Add Livable Or Storage Space Without Traditional Framing For A Second Floor.

Mono Truss

Mono Trusses Have One Slope Only, Where One Top Chord Is Longer Than The Other, Often Used For Lean-Tos, Extensions, Or Shed Roofs.

Useful For Single-Slope Additions, Roofing Over Awnings, Or Sunrooms Where A Low Profile Is Needed.

Parallel Chord Truss

Also Called A Flat Truss, The Parallel Chord Has Top And Bottom Chords That Are Parallel, Making It Suitable For Flat Or Low-Slope Roofs And Floors.

Common In Commercial Construction And For Long, Continuous Roof Decks Requiring Unobstructed Space Below.

Hammerbeam And Bowstring Trusses

Hammerbeam Trusses Are Traditional Timber Forms For Wide Church Or Great Hall Spans, While Bowstring Trusses Use A Curved Top Chord To Span Large Distances With A Distinctive Arch.

Both Types Offer Architectural Appeal For Large Open Spaces But Often Require Specialty Fabrication And Higher Costs.

Materials And Fabrication Methods

Roof Trusses Are Fabricated From Timber, Engineered Lumber, Or Steel, Depending On Span, Load, Fire Codes, And Budget. Prefabricated Wood Trusses Are Common For Residences; Steel Trusses Dominate Industrial And Long-Span Applications.

Engineered Lumber And Metal Connectors Improve Precision, Strength, And On-Site Efficiency Compared To Traditional Stick Framing.

Design Considerations: Span, Pitch, Loads, And Codes

Span And Roof Pitch Drive Truss Geometry: Higher Pitches May Require Different Web Configurations. Trusses Must Account For Dead Loads, Live Loads (Snow, Maintenance), Wind, And Seismic Forces Based On Local Codes.

Structural Engineers Or Truss Manufacturers Generate Shop Drawings And Load Calculations To Ensure Compliance With International Building Code (IBC) And Local Amendments.

Cost, Time, And Construction Advantages

Prefabricated Trusses Reduce On-Site Labor, Speed Construction Schedules, And Lower Waste, Making Them Economical For Many Projects. Cost Varies With Material Type, Span, Complexity, And Transportation.

Savings Are Often Greatest For Repetitive Residential Roofs; Complex Or Large Trusses Increase Fabrication Time And Shipping Expenses.

Insulation, Ventilation, And Mechanical Integration

Truss Selection Affects Insulation Strategy: Attic Trusses Provide Clear Attic Space For Traditional Insulation, While Scissor Or Vaulted Ceilings Require R-Value Within The Roof Plane And Proper Venting To Prevent Moisture Issues.

Coordination With HVAC, Ductwork, And Skylight Placement Should Occur Early To Avoid Costly On-Site Modifications.

Maintenance, Inspection, And Common Issues

Regular Inspections Should Check For Sagging, Connector Plate Corrosion, Water Intrusion, Insect Damage, And Changes Caused By Remodeling. Addressing Leaks And Ventilation Early Protects Truss Integrity.

Connector Plates Can Lose Strength If Exposed To Moisture; Replace Damaged Components Promptly And Consult A Structural Professional For Repairs.

How To Choose The Right Truss Type For A Project

1. Define Functional Needs: Determine Whether Attic Space, Vaulted Ceilings, Or Simple Economy Is The Priority.

2. Assess Site Conditions: Check Local Snow Loads, Wind Speed Maps, And Seismic Zone Requirements.

3. Consult A Structural Engineer Or Truss Manufacturer Early To Optimize Span, Material, And Cost.

4. Evaluate Access And Transportation Constraints For Large Prefabricated Trusses.

Early Coordination Between Architect, Engineer, And Truss Fabricator Minimizes Design Conflicts And Costly Rework.

Examples And Typical Applications

Building Type	Recommended Truss Types
Single-Family Home	Fink, Attic, Scissor
Apartment Or Townhouse	Parallel Chord, Fink
Barn Or Workshop	Gambrel, Howe, Pratt
Church Or Large Hall	Hammerbeam, Bowstring, Scissor

These Pairings Reflect Typical Performance, But Project-Specific Loads And Architectural Goals May Change The Optimal Choice.

Sustainability And Energy Considerations

Choosing Engineered Lumber From Certified Sources And Designing For Continuous Insulation Improves Environmental Performance. Trusses Can Facilitate Integrated Solar Mounting Systems If Designed For Additional Live Loads.

Proper Ventilation And Air Sealing Are Essential To Achieve Energy-Efficient Roof Assemblies Regardless Of Truss Type.

Working With Truss Manufacturers And Contractors

Provide Accurate Plans And Load Requirements To The Truss Manufacturer To Receive Detailed Shop Drawings And Bracing Instructions. Ensure The Contractor Has Experience Installing The Selected Truss Type And Follows Manufacturer Bracing For Temporary And Permanent Stability.

Verify Insurance, Warranties, And References For Both Fabricator And Installer Before Contracting.

Resources And Next Steps For Homeowners And Builders

• Consult Local Building Codes And The IBC For Minimum Load Requirements.

• Ask Truss Suppliers For Engineered Drawings, Spec Sheets, And Example Installations.

• Request A Site Visit From A Structural Engineer For Unique Or Long-Span Designs.

• Plan Insulation, Ventilation, And Mechanical Routing During The Truss Design Phase.

Involving Experts Early Reduces Change Orders And Ensures The Selected Roof Truss Type Meets Structural, Functional, And Aesthetic Goals.