Choosing the right roof truss is an important part of creating a strong, efficient and durable roof structure. Different truss configurations distribute loads in different ways, making certain designs better suited to particular spans, loads and building requirements.
One well-established option is the Howe truss. Recognisable by its distinctive arrangement of diagonal and vertical members, the Howe truss is designed to distribute loads efficiently across the structure. Although the design is also widely associated with bridges, it can be adapted for roof structures where its particular structural characteristics are beneficial.
Below, we examine how a Howe truss works, its advantages and disadvantages, and where this design may be appropriate for a roofing project.
What is a Howe truss?
The Howe truss is a triangulated structural framework consisting of a top chord, bottom chord, vertical members and diagonal members.
One of its defining characteristics is the orientation of its diagonal members. The diagonals typically slope upwards towards the centre of the truss. This arrangement allows forces to be distributed through the vertical and diagonal members and transferred towards the supports.
Like other truss systems, the Howe truss makes effective use of triangular geometry. Triangles provide structural stability while allowing loads to be carried over relatively long spans without relying on a solid beam of equivalent depth.
What sets a Howe truss apart?
The orientation of the internal web members is one of the easiest ways to distinguish a Howe truss from other designs.
A Pratt truss, for example, uses diagonals that run in the opposite direction. Warren trusses typically use a repeating series of triangles with fewer vertical members, while simpler King Post designs contain considerably fewer internal members.
These differences aren’t purely visual. Changing the orientation and arrangement of the webs changes how compression and tension forces travel through the structure.
The Howe configuration distributes forces through a repeating combination of diagonal and vertical members. This can create an efficient structure in which individual members primarily carry axial compression or tension rather than significant bending.
Advantages of the Howe truss
Efficient load distribution
One of the main strengths of a Howe truss is its ability to distribute loads across multiple structural members.
Instead of concentrating the load on one large beam, the triangular framework transfers forces through the chords and webs towards the supports. This efficient load path is one reason trusses can achieve substantial spans without becoming excessively heavy.
Suitable for longer spans
The Howe configuration can provide a lightweight structural solution across relatively long spans.
This makes the underlying structural principle useful where a designer wants to minimise intermediate supports and create larger unobstructed spaces beneath the structure.
The exact span possible in a roof application will always depend on factors such as material, roof covering, truss depth, spacing and loading.
Relatively simple geometry
Although more complicated than a basic King Post truss, the Howe design uses a regular arrangement of vertical and diagonal members.
Its repeating geometry can simplify design and fabrication compared with highly customised structural systems.
Structural efficiency
Trusses are effective because many of their individual members primarily work in compression or tension.
When correctly engineered, this allows the structure to use material efficiently while still providing the necessary strength and stiffness.
Material versatility
Howe trusses can be manufactured from different structural materials, including timber and steel.
For roofing projects, the appropriate material depends on the required span, loads, building design, environment and budget.
Disadvantages of the Howe truss
No truss design is ideal for every project, and the Howe truss has some limitations that should be considered.
It requires structural depth
A truss achieves much of its efficiency through its depth. As a result, a Howe truss can occupy significant vertical space compared with shallower structural alternatives.
For buildings where roof-space height is restricted, another truss configuration may therefore be more appropriate.
More members can mean greater complexity
Compared with very simple trusses, a Howe configuration contains multiple diagonal and vertical members.
That can mean additional connections and material, depending on the specific design.
It may restrict usable roof space
The internal web configuration can make a conventional Howe truss unsuitable where homeowners want a completely open attic or loft.
If usable space inside the roof is important, an attic truss or another purpose-designed system may offer a better solution.
It isn’t automatically the best solution
A common mistake is to assume that one truss type is inherently stronger or better than every alternative.
In reality, roof truss performance depends on engineering. Span, truss spacing, roof covering, wind forces, material properties and connection design all need to be considered before selecting a truss configuration.
Where is a Howe truss best used?
The Howe truss is well known for applications requiring efficient load distribution over longer spans. Historically, the structural configuration has been extensively used in bridge construction, including railway and pedestrian bridges.
The same structural principles can also be applied to roof structures.
For roofing, a Howe configuration may be considered where spans or loading conditions make its web arrangement advantageous. However, it should be compared with alternatives such as Fink, Pratt, King Post or other engineered trusses before a final decision is made.
Rather than choosing a truss simply by its name or appearance, the objective should always be to find the most efficient system for the particular building.
Factors influencing truss selection
Before specifying any roof truss, engineers need to consider the complete roofing system.
Important factors include:
- Building span and support locations
- Roof pitch and geometry
- Weight of the roof covering
- Wind and other environmental loads
- Truss spacing
- Timber or steel specification
- Ceiling and insulation loads
- Additional equipment such as solar panels
- Available roof space
- Architectural requirements
Professional engineering allows these variables to be evaluated together so that the chosen truss provides the required structural performance without unnecessary material or cost.
How Dezzo Roofing can help
At Dezzo Roofing, roof trusses are designed according to the requirements of the individual project rather than relying on a one-size-fits-all approach.
Our experience with both timber and lightweight steel roof trusses allows us to assess factors such as span, roof covering, loading and roof geometry before determining an appropriate solution.
By combining professional roof engineering with precision manufacturing, Dezzo Roofing can provide a truss system designed to deliver structural reliability, efficient installation and long-term performance.
Conclusion
The Howe truss is a proven structural design that combines triangular geometry with diagonal and vertical web members to distribute loads efficiently.
Its strengths include structural efficiency, relatively simple geometry and suitability for longer spans. However, its depth, internal web members and project-specific suitability mean it isn’t necessarily the best option for every roof.
The safest approach is to have your roof professionally engineered so that the truss design is matched to the building, roof covering and expected loads.
FAQs
What is a Howe truss?
A Howe truss is a structural framework consisting of top and bottom chords connected by vertical and diagonal web members. Its diagonals typically slope upwards towards the centre of the truss, helping distribute loads towards the supports.
What is a Howe truss good for?
Howe trusses are particularly useful for distributing loads efficiently across relatively long spans. They are widely associated with bridge structures but can also be applied to roof structures where their configuration suits the project’s engineering requirements.
Is the Howe truss the strongest?
There is no single “strongest” truss for every application. A Howe truss can provide excellent structural performance, but the optimal design depends on span, loads, material, connections and geometry. The strongest solution is one that has been correctly engineered for its intended application.
What are the disadvantages of a Howe truss?
Potential disadvantages include the vertical space required by the truss, the number of internal members and connections, and reduced usable space within a roof. Depending on the building and loading conditions, another truss configuration may offer a more economical or practical solution.