If you are building a home, you have to decide whether you want rafters or trusses for your roof construction. You are probably wondering what's the difference and does it matter which one you choose. We have done the research and have information to help you decide.
You have two options, rafters or trusses, for roof construction. Some of the differences between rafter and trusses include the following:
Please keep reading to find out more specific details about the differences between rafters and trusses, including the best situations to use each one.
Which is better, trusses or rafters?
Rafters and trusses are three-cornered wood structures that tie together and form a framework to support perimeter walls and a foundation for the roof of a building. They provide the triangular peak that is visually expected in a traditional roofline.
The answer to which one is better depends on the result you want for your home's interior and exterior. There are pros and cons to each one which we will discuss in this section.
Both rafters and trusses provide support, but the construction method is different with each one.
Rafters utilize the traditional roof framing method and are built on-site using a sticking framing pattern. Each piece is measured, cut, and fastened into place to form a frame for the roof. Rafters include several sections, including the rafter boards, ridge boards, collar ties, and ceiling joists.
Rafter construction uses sloping beams to form a triangle that supports the outside walls. Rafters generally use a larger dimension of lumber, with 2x8s and 2x10s being the standard choice. However, 2x12s and 2x14s can be used in specific designs.
A significant advantage to rafters is that it allows builders to customize a roof design. Homes with rafters also have more room available within the frame, which is another benefit when expanding the attic area into finished living or storage space. The added space also makes it easier to install insulation.
Trusses are considered pre-fab and built off-site, so a building plan and an advance order are required to create your customized package. Every truss you order will be a precise replica of the others because the trusses are fabricated using computer-generated specifications.
Once delivered to your job site, trusses are assembled. The final result is a roofing frame consisting of many small triangular configurations that form a design similar to a web. The construction design of trusses distributes the load more evenly to outside walls and is stronger than rafters even though smaller lumber is used. Trusses are usually built using 2x4s.
Cost is always a concern when building a new home. Staying on budget is essential, and construction is prone to unforeseen events that can add an unwanted expense to the final cost.
One area where you can plan to save money is the roof area. However, savings are only an option if your building plans include a standard roof and don't want useable attic space.
Is it cheaper to use trusses or rafters?
Overall, trusses are the less expensive option because they are built using a uniform mass production process. This process saves labor costs by eliminating the time and expense of measuring, cutting, and building the entire frame on-site. The crew only needs to fasten the trusses in place. However, you need equipment or a crew on the job site to unload and lift the trusses to the roof.
Rafter cost requires figuring the labor cost of the roofing crew and the raw material costs. It can take a crew up to a week to complete rafters for an average-size home. Quite a bit of labor costs can accrue during this time.
When comparing the cost of rafters versus trusses, you have to include all factors like labor and delivery and not just raw material cost. Trusses might look like the more expensive option if only considering the cost of raw materials. However, when you factor in the labor costs associated with rafters, you will find that, overall, trusses are the less expensive option.
Rafters are built on-site, so you have to order the materials and then wait for the construction crew to build each one. Typically, it takes up a week or longer for a crew to build rafters.
Trusses are mass-produced in a factory. While there may be inventory available in a warehouse, a package to match your exact building plans probably isn't going to be available, so you have to plan ahead. There, typically, is a 3-4 week lead time on truss production, so you have to place your order with enough advance notice to avoid stalling production and throwing off the timeline of your job.
Once they arrive, trusses can be installed in about a day. This means that your home's skeleton can get under cover faster, avoiding exposure to the outside elements for less time. If you need your roof timeline to move more quickly, then trusses might be the best option for your construction project.
As previously mentioned, trusses are built in a factory, so they check quality control. You can expect each truss you receive to be almost identical.
Trusses come in a package that includes everything needed to assemble your framing project. Inventory items will be labeled to correspond to the instructions to avoid confusion. Directions for spacing and fastener placement will be included, ensuring uniform quality if followed. There is no guesswork. However, there isn't much flexibility if you change your mind about the design.
Rafters are built on-site, so each one may not be thoroughly inspected. The quality is contingent upon the experience and work ethic of the laborer doing the work. Also, because many laborers work on a job site, there may be quality differences when different laborers build different sections.
Span is the distance covered by the lumber in a rafter or truss before additional structural support has to be installed. When considering the span of rafters or trusses, a builder has to consider many factors such as the slope of the roof, type and size of wood being used, and load, especially when heavy snow occurs frequently.
Calculating span should only be done by an experienced builder. While charts are available that address lumber size, lumber species, and live or dead load, the information isn't for a novice.
Large spans are desirable in structures because of increased interior space and decreased material and construction costs.
Trusses can accommodate a larger span than rafters. Rafters are noted to have a maximum span of 30 feet, while trusses can span technically span up to 80 feet even though that large of a span is impractical and very costly. Typically trusses span up to 40 feet but can reasonably span to 60 feet if needed.
Rafters don't have to be delivered because they are built on-site. This scenario works well when the job site is remote. Raw materials can often be delivered easier than large pre-built trusses. If your new home is a secluded hideaway in a location not easily found, then you may require rafters.
Trusses are delivered using a semi-trailer, so your job site must be accessible, or trusses won't be an option. So don't forget to factor the delivery charge into the overall cost. Generally, trusses are still less expensive than rafters, even with freight costs included. However, you should expect that the more difficult the location is to reach, the more expensive the freight charges.
When delivery is required, weather is also a factor. Too much rain or snow can create hazardous conditions for a semi-trailer. If delivery gets delayed, then your build is also delayed.
Are trusses as strong as rafters?
Trusses offer more support than rafters because of the additional reinforcement beams built within the outer beams. The additional beams create a web that allows the weight of the roof to be distributed equally.
Rafters and trusses both offer a functional framework to support the roof of a home. However, there are differences between the two. Rafters are suitable for customization and allow expansion into the attic space, while trusses offer a more cost-effective alternative for a standard roofline.
If you are considering a new porch or roof and need ideas, consider reading "15 Porch Overhang And Roof Ideas To Inspire You."
For more information about roofing, read "How Big Is A Square Of Roofing Shingles?"