Roof trusses are engineered frameworks that support a roof and transfer its weight to a building’s walls or beams. Their shapes affect roof pitch, usable attic space, construction cost, and how a building handles loads such as snow and wind. Common roof truss types include gable, hip, fink, scissor, attic, and mono trusses. Knowing how these styles differ can help homeowners compare plans and discuss options with a builder or structural engineer.
What Is a Roof Truss?
A roof truss is a structural assembly of connected members, usually made from lumber or steel, that forms a rigid framework. Most residential wood trusses use top chords, bottom chords, and internal webs arranged in triangles. This geometry helps distribute loads through the frame to its supports.
Trusses are commonly manufactured off-site to specifications prepared for a particular building. Many wood trusses use metal connector plates pressed into the joints, although other materials and connection methods are available. The truss design must account for the building’s dimensions, roof shape, materials, support locations, and local loading conditions.
A roof truss is not the same as a roof covering. Shingles, metal panels, underlayment, and sheathing form parts of the roof assembly, while the truss is part of its supporting structure. Trusses also differ from rafters: rafters are individual sloping framing members assembled on-site, whereas a truss is a pre-engineered framework.
Common Roof Truss Types
King Post Truss
A king post truss has a central vertical member connecting the peak to the bottom chord, along with two sloping top chords. It has a simple, recognizable triangular shape and is often used for smaller structures, such as garages, porches, and pavilions. Its suitability depends on the required span and loads; it is not automatically appropriate for every small building.
The uncomplicated layout can suit exposed or traditional designs, but the central post and web arrangement can limit clear space below. A designer should confirm whether the truss can meet the project’s structural requirements and architectural goals.
Queen Post Truss
A queen post truss generally has two vertical posts connected by a horizontal member, creating a wider open area than a basic king post arrangement. Its appearance can work well in traditional or open-ceiling spaces. Like other named truss forms, the label describes a general configuration rather than guaranteeing a particular span or capacity.
Fink Truss
The fink truss is one of the most common configurations in residential construction. Its internal webs often form a W pattern between the top and bottom chords. The web arrangement distributes forces through multiple members and can be efficient for many conventional pitched roofs.
Fink trusses are often selected for standard homes because they can be manufactured in a range of sizes and roof pitches. The webbing typically occupies much of the attic, however, making the space difficult to use for storage or conversion without a truss design specifically intended for that purpose.
Howe Truss
A Howe truss typically combines diagonal web members with vertical members. The pattern is associated with bridge design, but Howe-style layouts also appear in roof trusses. The arrangement and member materials affect how forces travel through the structure; the configuration should not be chosen by name alone.
For residential roofs, a manufacturer or engineer evaluates whether a particular Howe-style design suits the span, loads, and support conditions. Its internal members may restrict open attic space, as they do in many conventional truss designs.
Pratt Truss
A Pratt truss generally has vertical members and diagonals that slope toward the center of the span. Pratt configurations are common in some bridge and structural applications and may be adapted for roof framing. Their performance depends on the complete engineered design, including member sizes, connections, materials, and loading.
Warren Truss
A Warren truss uses a repeating series of triangles, often with alternating diagonal members and few or no verticals in its basic form. The layout can create a visually clean pattern, but roof versions may include additional members or modifications. A truss engineer determines whether the geometry is appropriate for the building and its conditions.
Scissor Truss
A scissor truss has bottom chords that slope upward toward the center, forming a vaulted ceiling beneath the roof. It can provide a more open interior than a standard flat-bottom truss while retaining a framed roof structure.
The ceiling slope, roof pitch, insulation strategy, and available depth all affect the finished space. Scissor trusses often create less room for insulation at the eaves than raised-heel designs, so the designer should coordinate the structure with energy-code requirements and the planned ceiling assembly.
Attic Truss
An attic truss, sometimes called a room-in-attic truss, is designed to create usable space within the roof structure. Its configuration leaves a central area that may accommodate a room, storage, or access, depending on the design. It can be useful when a building plan calls for an upper-level space without conventional full-height walls across the whole floor.
An attic truss is not simply a standard truss with some webs removed. It must be engineered for the intended floor loads, clearances, stairs, openings, and roof loads. Local building codes may require specific fire protection, egress, and ceiling-height provisions for habitable space.
Mono Truss
A mono truss has a single sloping top chord, creating a one-way roof slope. It is commonly used for lean-to additions, porches, sheds, and buildings with a single-slope roof. Its height, slope, bearing points, and drainage details must match the design and site conditions.
Hip Truss
A hip roof slopes down on all sides rather than ending in vertical gable walls. A hip truss system generally includes multiple related trusses, such as a supporting girder truss and shorter jack trusses, to form the roof shape. The precise layout depends on the building’s dimensions and roof plan.
Hip roofs can be architecturally appealing and may perform well in some wind conditions, but no roof shape is automatically windproof. Connections, bracing, sheathing, and the complete load path are critical. Local wind exposure and code requirements should guide the design.
Raised-Heel Truss
A raised-heel truss lifts the roof above the top of the exterior wall, creating extra depth near the eaves. That space can help maintain insulation thickness where a conventional low heel would compress insulation. The benefit depends on the overall roof assembly, air sealing, ventilation approach, and applicable energy requirements.
Raised heels may affect exterior wall height, fascia details, and roof appearance. They should be coordinated early with the building design rather than treated as a last-minute insulation adjustment.
Parallel-Chord Truss
A parallel-chord truss has top and bottom chords that run approximately parallel. It can be used for low-slope roof or floor applications and may help create a consistent depth for insulation, services, or a flat ceiling. The term describes the chord arrangement; it does not establish whether a roof is flat or how much load it can support.
Bowstring Truss
A bowstring truss has a curved or polygonal top chord paired with a flatter bottom chord, producing a broad arched roof profile. It is more often associated with large-span or specialty buildings than ordinary houses. Because of its geometry and potential scale, it calls for project-specific engineering and careful attention to connections and lateral stability.
Roof Shape and Truss Design Are Different
Some terms describe the roof’s exterior form, while others describe the truss’s internal framing. A gable or hip roof refers to the roof shape. Fink, Howe, and Warren describe truss web patterns. A project can combine a roof form with a truss configuration selected to support it.
This distinction matters when comparing bids or discussing a plan. For example, “hip roof” does not identify a single truss design, and “scissor truss” describes a ceiling-and-frame arrangement rather than a complete roof covering. The construction documents should specify the required geometry and performance, not rely only on a general style name.
Roof Truss Types at a Glance
| Truss Type | Typical Feature | Common Consideration |
|---|---|---|
| King post | Central vertical post | Often suited to smaller or decorative structures |
| Fink | W-shaped web pattern | Efficient for many conventional pitched roofs; limited attic access |
| Scissor | Sloped bottom chords | Creates a vaulted ceiling; coordinate insulation depth |
| Attic | Open central area | Must be designed for intended floor use and access |
| Mono | Single sloping top chord | Useful for one-way roof slopes and additions |
| Hip | Multiple trusses form slopes on all sides | Requires a coordinated system and appropriate connections |
| Raised heel | Higher bearing point at the eave | Can provide more room for insulation near the wall |
| Parallel chord | Top and bottom chords run parallel | Useful where consistent truss depth is needed |
How to Choose a Roof Truss Style
The right roof truss depends on more than appearance. Architects, builders, truss designers, and structural engineers consider how the building will be used, how the roof will look, and how loads will reach the foundation. Key factors include:
- Building span and layout: The distance between supports, wall locations, and any interior bearing points affect the framing design.
- Roof pitch and shape: The desired slope, eaves, hips, valleys, and overhangs influence the truss layout.
- Attic or ceiling needs: A flat ceiling, vaulted ceiling, storage area, and habitable attic each call for different planning.
- Local loads: Snow, wind, and other design loads vary by location and project. The building department’s adopted code and site conditions matter.
- Energy performance: Insulation depth, air sealing, ventilation, and thermal bridging should be considered as part of the roof assembly.
- Openings and equipment: Skylights, chimneys, ducts, and mechanical equipment need coordinated locations. Truss members should not be cut or altered to make room for them.
- Delivery and installation: Large trusses require suitable access, lifting equipment, temporary bracing, and a safe installation plan.
Cost and Construction Considerations
There is no universal price for a roof truss. Cost depends on dimensions, lumber and connector specifications, design complexity, quantity, location, delivery, and installation. A standard configuration may be economical for one building, while a custom shape or attic design may require more material, engineering, or specialized handling.
Comparing estimates requires more than comparing the word “truss.” The proposals should reflect the same roof geometry, design loads, materials, bracing requirements, openings, and delivery scope. Builders should confirm whether engineering documents, installation labor, crane service, and temporary bracing are included.
Safety, Codes, and Professional Design
Roof trusses are engineered structural components. Their design and installation should follow the approved construction documents, the manufacturer’s instructions, and the building code adopted by the local authority. Design loads and code provisions vary, so a generic chart or online span estimate cannot replace project-specific engineering.
Trusses should be stored, lifted, braced, and connected as specified. Temporary bracing is important during installation, before the permanent roof sheathing and other components stabilize the structure. The Structural Building Components Association provides industry guidance on handling and installing structural building components.
Never cut, drill, notch, or remove a truss member without written approval from the truss designer or a qualified structural engineer. Such changes can disrupt the load path and weaken the assembly. If a conflict arises with plumbing, HVAC, a skylight, or another building component, the design team should resolve it before modification.
For residential wood construction, the American Wood Council’s codes and standards resources offer information on wood design and applicable standards. Local building officials determine which code requirements apply to a specific project. Plans should be reviewed and permitted as required in the project’s jurisdiction.
Questions to Ask Before Ordering Trusses
- Which truss type and roof geometry are shown on the approved plans?
- What design loads and building-code criteria apply at the project location?
- Are attic access, storage, or habitable-room loads included in the design?
- How will insulation, ventilation, and air sealing work at the eaves and roof peak?
- Have skylights, chimneys, ducts, and other openings been coordinated with the truss layout?
- Who supplies the permanent and temporary bracing details, and who is responsible for installation?
- What documents, inspections, and approvals are required before construction?
Clear answers help ensure the selected roof truss style fits the building’s appearance and function while meeting structural, energy, and code requirements.