Rafters Vs. Trusses - What’s the Difference Between Rafters & Trusses? (2024)

It is common to read that “rafters are the way they used to frame roofs. Now everyone uses trusses.” First, that is plain wrong, and an oversimplification at best.

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Secondly, rafters can have important advantages over trusses in certain building projects; If you’re planning for an out-of-the-ordinary, custom roof design or want to make use of the attic space, then rafters might be more appropriate.

In this guide, we will define roof trusses and rafters and explain the pros and cons of each for comparison. We will also outline the best uses of each, so you can decide whether rafters or trusses are the right choice for your building project.

Quick Overview: Rafters and Trusses:

It is certainly true that trusses are more commonly used than rafters. They’re more economical to build and offer the same or greater roof strength. There’s a lot to like.

However, trusses don’t give you the opportunity for creativity in home design that rafters allow. There’s more on the pros and cons below, but first let’s define the terms:

What Is a Roof Rafter?

Rafters are the traditional means of framing a roof.

Building a roof frame with rafters is known as stick framing. This means that each rafter is built on the job site using dimensional lumber. Every piece is measured, cut, and fastened together to form the rafter. The stick framing process is labor-intensive.

This diagram shows the major components of a traditional rafter, though slightly different styles can be built.

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  1. Rafter Boards: The boards creating the slope of the roof are wider than lumber used to build trusses – 2x8s, 2x10s and 2x12s are most common in rafters vs. 2x4s in trusses. Rafter boards are fastened to the ridge board at the peak and the top plate where they join the wall.

In finished space, insulation is placed between the rafter boards and drywall, or other material is fastened to the face of the boards.

  1. Ridge Board: The ridge board must be the same width as the rafter boards. In heavy-duty construction, a ridge beam might be used instead.
  2. Collar Ties: These horizontally installed boards give the trusses strength and stability.
  3. Ceiling Joist: This board forms the bottom member of each rafter and, of course, the ceiling of the space below.

In unfinished space (an attic), insulation is typically laid between the joists. The joists might then be covered with OSB or plywood to form an attic floor for storage. The rafters are similar to trusses in this regard.

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What Is a Roof Truss?

One good roof truss definition is, “a prefabricated wooden structure that integrates a triangular webbing of structural members to provide support for the roof above while tying the outside walls of the house together.”

The diagram illustrates the “webbing” design of wood truss components.

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Trusses and rafters have many common parts including the sloping rafter boards and bottom joists that form the ceiling of the space below.

The major functional difference between the two is that trusses are built mostly with 2x4s in place of the wider dimensional boards. To compensate for using materials that aren’t as strong, more material is used.

The key practical difference is that trusses are built in a factory (prefabricated) under ideal conditions. Cuts are automated for tremendous precision.

Comparison of Pros and Cons

While trusses and rafters can handle similar loads, there are clear distinctions in essential areas that will help you choose which is right for your building project.

Truss Advantages

Price: When the cost of a prefabricated truss package is compared to the material and labor costs to build rafters on site, the cost of trusses is 30% to 50% less.

Accuracy: There are fewer mistakes made in the fabrication of trusses. They are built in a controlled environment. Specifications are loaded into software, and truss components are digitally measured and cut.

As noted, the precision is impressive. Every one of them exactly meets the specs.

Time and Weather Risks: Truss installation takes about a day on most 2,500 square foot homes. The trusses get installed, and the roof sheathing goes on, protecting the rest of the structure from weather. And the roof is ready for the installation of shingles.

On the same home, rafters might take a week to build, depending on the size of the crew. This slows the overall pace of the project, and the framing is susceptible to weather exposure for much longer.

Pro tip: You can only take advantage of the short installation time for trusses if you get them ordered well ahead of when they’re needed. Lead time is usually 3-4 weeks but could be longer during busy construction months.

Excellent Strength and Span: The webbing effect of the truss members creates outstanding structural strength, even though smaller lumber is used.

Did you know? Truss spans can reach up to 60 feet.

According to the American Wood Council, the maximum span for rafters is about 30 feet, and that’s with a relatively low load of 20lbs per square foot.

As the load goes up for snow in northern climates or for heavy roofing material like tile, the span length decreases.

DIY Friendly: Truss installation is much easier than building rafters one at a time. Your truss package will come with detailed installation instructions for spacing and fastening.

If there are trusses of differing sizes or type, such as gable trusses, they will be numbered or otherwise marked for easy identification.

Truss Disadvantages

If trusses were perfect, this discussion would be useless. Here are a few cons for trusses.

Weight and Size: Assembled trusses are big and heavy. This means a couple things. You’ll need them delivered on a semi, and that raises shipping costs (though trusses are still the economical choice).

You might need to rent a boom or crane to get them to the roof. If you’re building in the spring, the boom or crane company might say, “We can’t get our equipment onto the worksite until the muddy ground dries up.” That could cause unexpected delays not common to building with rafters.

Their sheer weight makes them more difficult to work with, especially when they span 40 feet and beyond.

Access: Building a mountain getaway or a home on an island? Good luck getting the trusses to your property! Transporting them will either be impossible, or the cost will be exorbitant.

Ceiling Design Limitations: The structural webbing of trusses limits what you can do with the space beneath and between them. Forget about a finished attic.

And most homes with trusses have flat ceilings. Scissor trusses are available for cathedral ceilings, but the angle of the ceiling can’t be as steep as when rafters are used.

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Rafter Advantages

Many of the rafter pros reflect truss cons, so we’ll make them brief.

More Space or More Drama: Have you ever stood in the attic of a home with a roof pitch of 6/12 or steeper? There is an enormous amount of unused space in there!

Using rafters takes advantage of the area beneath the roof and above the ceiling of the lower floor. Use your attic as a bedroom or office, for example.

Don’t need it for living space? Consider opening it to the lower floor to create a truly dramatic vaulted ceiling.

Use them Anywhere: Since rafters are stick built on the job site, they’re ideal for hard-to-reach building locations. The material can be brought in on a pickup truck or boat, if necessary.

We’ve seen rafter material transported by helicopter. Pricey, yes, but at least possible compared with getting trusses to that sort of remote building site.

Zero Lead Time: Going to work on a project “spur of the moment”? Then rafters are a good choice, since they don’t have to be ordered and built ahead of time.

Small Projects: Many builders choose rafters for sheds, small additions, or cabins to save the hassle of ordering and waiting on trusses.

Rafter Disadvantages

Again, these have been alluded to.

Cost: When materials and the much-higher labor rate is factored in, rafters are the clear loser in the cost battle.

Pace: The pace of building slows noticeably once the walls are up and work shifts to hand-building each and every rafter. If inclement weather rolls in, expect delays as the entire structure gets tarped to wait out the rain.

At worst, heavy rains during construction can lead to damage to the home’s structure that requires an insurance claim. We’ve seen that too.

Skill Required Factoring angles on stick-built rafters is complex. Frankly, many licensed builders today would struggle to get measurements and angles correct to produce 20 or more rafters exactly alike – and exactly in accordance withthe specifications.

Best Uses for Trusses Vs. Rafters

In a nutshell, trusses are right for most projects. Rafters are a better choice for specialty projects.

Use trusses when:

  • Your home-site is easily accessed.
  • You don’t prefer finished attic space.
  • Scissor trusses will provide enough steepness for any vaulted ceilings in the plan (consult your architect to determine that).
  • Cost is a significant priority in design.

Use rafters when:

  • You want to maximize living space within the home’s structure.
  • A steeply vaulted ceiling is preferred.
  • The building site cannot be reached by an affordable method of transportation for trusses.

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Rafters Vs. Trusses - What’s the Difference Between Rafters & Trusses? (2024)


Rafters Vs. Trusses - What’s the Difference Between Rafters & Trusses? ›

Roof rafters are used in traditional stick-framed architecture. Trusses offer a new way of building a roof, and are less expensive than rafters. Rafters are built on-site, while trusses are pre-fabricated. Trusses are considered stronger, but offer less flexibility for remodeling.

What is the difference between a truss and a rafter? ›

rafters is the fact that trusses are prefabricated wooden structures while rafters are usually built on-site. For trusses, the triangular webbing of structural pieces not only provide support for the roof, but they also tie the outside walls of the home together.

Why do builders use trusses over rafters? ›

Roof trusses can be more cost-effective than rafters in many cases. Because they are prefabricated, they can be mass-produced, which can reduce the cost per unit. In addition, because they are lighter and easier to install than rafters, they reduce labour costs. Design flexibility.

What is the cost difference between trusses and rafters? ›

Replacement or installation of roof trusses costs between $5 to $14 per square foot, and for rafters, the cost ranges from $7 to $30 per square foot. Generally, the cost of rafters, purlins, and joists is more expensive because they are constructed on-site.

What is the wood between rafters called? ›

Collar Tie

a timber placed horizontally and between rafters that control spreading or sagging of the rafters, usually placed parallel to the girts which connect rafter pairs at a given height.

Can you mix trusses and rafters? ›

Yes, you can create a hybrid roof system that incorporates both rafters and trusses. This approach allows you to combine the design flexibility of rafters with the structural efficiency of trusses in specific sections.

Do trusses have rafter tails? ›

Rafter tails are the exposed exterior portion of a building's wood structural truss that projects beyond the perimeter wall of the structure. This structural element is secured to the top of the wall or tie beam and then projects to support the soffit overhang.

Do roof trusses need a ridge beam? ›

If your home has a roof slope of less than 3/12, you will need to use a ridge beam. A ridge beam is also a good choice if you want to maximize attic space.

What is the most common spacing for rafters and trusses? ›

What Is The Standard Roof Rafter Spacing? The standard roof rafter spacings measured on-center are 12″, 16″, 19.2″, and 24″. The International Residential Building Code (IRC), which is the basis of most North America's building coide, identifies these standard industry measurements.

What is the most cost effective truss? ›

King post truss cost

King post trusses are among the most common and cost-effective styles due to their simple design using the fewest components—one bottom chord, two top chords, and one center vertical "king" post. King post trusses are designed for short-span applications like a garage or home addition.

Which is better wood or steel trusses? ›

Steel is incredibly durable: Steel trusses are very durable when coated properly. They can withstand high-stress situations and also require very minimal maintenance. Complete pest resistance: Wood trusses are vulnerable to pests, a major threat in areas prone to termite and other wood-boring pest infestations.

Is it cheaper to buy trusses or build them? ›

Trusses built on-site are more costly because the labor cost is higher.

What is considered a rafter? ›

In the field of construction, rafters are a series of sloped structural pieces that will extend from a ridge area to the plate of a wall or an eave. They are used to support the load of the building, especially the roof area.

Are rafters or trusses better for a shed? ›

What are the advantages of using trusses? They have superior strength and span. Although not much of a factor in a smaller building project like a shed, truss spans can be as long as 60', where as rafter spans are usually no longer than 30'. They are easier to build than rafters.

Are the terms rafter and truss interchangeable and describe the same component? ›

Rafters vs.

Rafters and trusses are both structural components that frame the roof. Rafters are framing boards that extend from the ridge to the wall plate and are usually built on site. Trusses are usually prefabricated off-site in a triangular webbing frame to provide support for the roof and exterior walls.

Do rafters hold up roof? ›

Yes. In fact, in most cases, they will be used together to form a very strong structure. Other components like collar ties augment this design to provide additional strength and support. In a typical roof system, rafters provide vertical support for the roof and ceiling joists provide horizontal support.


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