How Large Can Roof Trusses Really Get? A Builder’s Guide to Wide-Span Roofs

Did you know that roof trusses, as a structural element, have been around since 2500 BCE? That was the era of the Bronze Age, and historical records trace their first use back to the lake dwellings of this particular time period! 

 

That said, timber trusses started gaining popularity sometime during the Middle Ages. Fast forward to today, and they are an indispensable part of most modern Ontario homes – whether single-unit or multi-unit buildings.

 

However, despite their prevalence in construction, many builders, architects, and even homeowners still wonder:

 

How large can roof trusses really get? 

 

Experts at Fonthill Lumber Inc. – Ontario’s most trusted lumber yard for more than 75 years – will tell you that they can get larger than you expect them to. However, the actual number will depend on a myriad of different factors. 

 

From span and height to roof pitch, load requirements, building use, and regulatory codes – every single one of these plays a critical role in how large a roof truss can get. 

 

Understanding these factors can help you construct more open and wider spaces that may just set the record for being the largest of its kind in the area – all without expensive redesigns, delays, or long-term performance issues! Let us show you what we mean in today’s blog. 

 

 

What Roof Truss Size Really Means

 

Though common, it is a misconception that the size of a roof truss can be defined by its span alone. Its actual size depends on the combination of different measurements that primarily include the following: 

 

• Span: The span of a truss covers the horizontal distance between the bearing points on each of its ends
• Overall height: This concerns itself with the vertical dimension of the structure, from its bottom chord to its peak
• Roof pitch: This covers the slope of the roof, which directly impacts how ‘large’ the final truss will be
• Profile and configuration: This governs the measurement of the truss’ internal load-bearing web layout

 

Why are each of these important? It is highly likely for two roof trusses of the same span to be of very different sizes overall when their pitch and loading requirements are factored in. 

 

Take, for example, a shallow pitch truss. It might appear smaller, but it hides complex internal webbing to meet snow load requirements. On the other hand, a steep truss will not need as many internal members but is bound to be taller. 

 

It is also important to note that in the case of trusses, “bigger” does not generally mean “wider”. A larger truss could be taller, heavier, or even more complex or intricate on the inside. That is why span should not be the only factor when deciding the overall size of a roof truss. 

 

Remember: longer spans do not make for taller trusses, and steeper pitches do not allow wider structures. Both have to work together to create a truly sizable truss.

 

 

What Are The Dimensions Of A Typical Residential Roof Truss Span?

 

Since span definitely contributes to the appearance of colossal trusses, let’s talk about their average dimension. The roof trusses of most Ontario homes span anywhere between 30 ft and 60 ft, again depending on the project’s load requirements and overall design. 

 

Often, the largest roofing systems can be found in open-concept design homes, garages, and custom builds. 

 

The reason why roof trusses can reach 60 ft spans boils down to the fact that they are engineered systems that completely take the guesswork out of construction. Built on the foundation of precise loads and accurate measurements, these structures enable the creation of significantly longer spans than rafters do, that too without compromising their strength and integrity. 

 

 

What Can Limit The Size Of A Roof Truss?

 

How large a residential roof truss will be ultimately depends on a few key factors. These include:

 

• Load requirements

For Ontario projects, snow loads are a critical consideration that consequently affects truss size. Trusses should be designed well-enough to handle all kinds of loads, including the weight of roofing materials, snow, drift, and seasonal freeze-thaw cycles. 

 

• Roof pitch

While steep roofs can handle snow loads without the need for complex internal layouts, their exteriors require a greater amount of material to build. Similarly, roofs with lower slopes demand intricate web layouts. What we mean to say is final truss geometry is largely dependent on its pitch. 

 

• Material selection

Your choice of truss material – timber or metal – can also alter its capacity to produce larger structures. Although engineered lumber roofs guarantee predictable performance, the design expectations of your project can ultimately limit their final size. 

 

 

Factors That Increase Roof Truss Size

 

On the other side of things, there are a few factors that can actually increase truss size beyond the standard span of 30 ft to 60 ft. These factors can help you build larger roofs, but only if you plan early and efficiently. 

 

• Wider building footprints

Grand bungalows, sprawling multiple residential units, and even the occasional commercial building can increase truss size significantly. Ultimately, the width of the building determines how long the span of its truss will be without requiring intermediate support. To create such expansive structures without compromising their strength, it is necessary to build deeper truss profiles with additional webbing.

 

• Lower roof pitches

As we mentioned before, steep pitches can lead to the creation of trusses with smaller spans. However, lower pitches open up the structure considerably. That said, extra reinforcement is required to build overall larger profiles so they can safely handle different kinds of loads without collapsing.  

 

• Vaulted or cathedral ceilings

If the aim is to build a vertically larger truss, vaulted or cathedral ceilings are an excellent choice. They help in the creation of roomier interiors by accommodating really high ceilings and contributing to the grandeur of the entire project. 

 

• Fewer interior supports

If your project demands open concept layouts, you get the flexibility to use trusses of larger sizes. Eliminating interior load-bearing walls, these roofs rely on exterior walls to support their loads. 

 

 

Why Roof Trusses Outperform Traditional Framing Methods For Wider Spans

 

Traditional rafters may have been a popular choice once upon a time, but builders quickly realized they are not the best option for the creation of expansive spaces that modern Ontario homeowners demand. Why? Because rafters require multiple interior load-bearing walls to support them, this creates breaks in living areas, thus making them smaller. 

 

Roof trusses, on the other hand, use interconnected webs that allow the efficient transference of force to exterior walls or any other designated load-bearing points. This not only brings down the cost of construction, but it also enables the creation of:

 

• Homes with open concept layouts 
• Wide garages
• Vaulted ceilings
• Large common areas

With pre-engineered roof trusses, you get the flexibility you need to build truly opulent and spacious structures in a code-compliant and precise manner. 

 

 

Fun Fact: The Largest Known Roof Truss In The World

 

Though it is made of metal, the Globe Life Field – a major league baseball stadium in Texas – features a massive retractable roof that is made of ten steel trusses in total! These trusses span a whopping 620 ft, north to south, making them one of the largest of their kind in the whole world! It’s an incredible feat of engineering! 

Other large structures where truss spans go way beyond their typical width include agricultural barns and structures, commercial spaces, and multi-unit residential builds. You can expect each of them to be wider than 60 ft. 

 

Conclusion

 

Although it is possible to build really large trusses, there is no magic number or maximum limit as such. The only thing that really matters is choosing the right roof truss type for your project and executing it to perfection. Of course, that requires partnering with the right truss manufacturers at the early stages of construction and design. 

 

Fonthill Lumber Inc. is the leading designer and manufacturer of floor and roof trusses in Welland, Ontario. Engineered with precision, our code-compliant trusses can help you build exceptionally large roofs if your project requires. Contact us to turn your ambitious construction plans into strong, tangible, and long-lasting results. 

 

 

FAQs

 

Is there a maximum span limit for roof trusses?

No. There is no single maximum number. The span of your project’s roof truss depends entirely on its requirements in terms of design, load, etc.

 

Are larger roof trusses more expensive?

While they are likely to be more expensive due to their complexity and material requirements, the final price depends on your project’s design, load requirements, and other critical parameters. 

 

Why should builders involve a truss supplier early in the design process?

Involving a truss designer in the early stages of construction and planning can help you avoid costly delays and redesigns.