Here we share our rafters vs trusses design guide including what they are, differences and pros & cons. One of the most important decisions when building a home is going to be the roofing design. The roof not only affects how the entire exterior of the home looks, but it also decides how you are going to protect your home from outdoor elements.
Two of the main methods for framing a roof are with Roof Rafters and Roof Trusses. These two options have many pros and cons that differ from one another that are discussed below.
Roof rafters are an older method that is tried and true, while roof trusses are coming in to give it a run for its money (literally).
It’s good to be said that roofs are not something that should be messed with when it comes to amateur do it your-selfing. When making changes to the home, make sure to consult a structural engineer, or contractor to make sure any changed that are being made are safe and legal.
What Is A Roof Rafter?
A roof rafter is framing that is used in roofing. This is the traditional method used for the framing, and the ‘rafter’ is one of the main pieces used.
A rafter board is used to make the slope of the roof, where it gets nailed or screwed together with the ridge of the roof and the top of the exterior walls. These tend to be paired with ceiling joists to connect together to create what we call an attic.
This form of building can also be called stick framing, which is measured and cut on the job site. While rafters are traditionally made from lumber, they have recently moved to having steel options for rafters.
Rafters are not something that are typically seen from the interior of the home, unless they are especially designed to be that way. You can read more about the different types of roofs here.
What Is A Roof Truss?
By definition a roof truss is a wooden structure that is prefabricated. The wooden truss is laid out in a triangular webbing design to give support.
Truss designs include different chords, ties and beams to create the overall roofing system. This method helps to evenly distribute the load of the roofing for better strength. This is a newer kind of design that involves a lot less on site work and time spent for the roofing.
Roof trusses are less expensive than the rafter choice dude to the ability to be massed produced off sight, unfortunately they are a great deal less customizable because of this though. These have become increasingly popular and are what are mainly used in buildings now.
Difference Between Rafters And Trusses
There are a few key differences between rafters and trusses that help you either figure out what you have now, or what you would like to have in the future. Some of these key differences can sway you from one direction to the other.
Below are a list of pros and cons of each type to better decipher which is right for your home.
Trusses Pros and Cons
Trusses are great for roof for many reasons and can be a splendid framing method for a home in any location.
Quality Control: Quality control is a huge one, since the materials are built in a factory, in a controlled environment, the accuracy of them are extremely high.
Additionally, the individuals working on these are specialized to only work on the trusses all day, every day, so they really know what to keep an eye out for.
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Quality control is also kept due to the quicker installation that leaves the roof framing from having to be left to the elements for too long before it is covers with sheathing.
Delivery: Another plus is that since these items are built off site, they can be delivered right on schedule to be installed the day of or next day so that materials don’t need to take up too much space.
Plus using that method opens up the workers to complete other tasks until the trusses arrive. This saves time in shipping as well as overall labor since they are pretty easy to install once they arrive on site, they can typically be finished in a day or two depending on the size and the crews.
Cost: This also saves on the cost because of the labor reduction as well as the materials are a bit lower in cost compared to the rafter system.
Strength: On top of all the logistics of getting the trusses built, they are actually stronger than the traditional rafter system. This is because of the braces that the design includes, giving it a better weight distribution.
There are a few downsides when it comes to the truss system for roofing that set it apart from the rafters.
Attic Space: First, trusses take up a lot more space, leaving not much room in an attic, and not allowing for decorative open ceilings.
While the cost of labor is decreased, the up from cost is going to be a bit higher than the rafters since there is more material overall.
Scheduling: Another consideration is that this is built off site and has to be made and scheduled for delivery in advanced, if the project if running ahead or behind this date could cause trouble.
Plus the site needs to be big enough to accommodate the delivery, not to mention the potential difficulties of shipping something that large.
Changes: As mentioned, these are built off site, which means they will be built to the dimensions sent to them, if there are any last minute changes or shifts it could cause a lot of trouble, and end up costing a lot if it needs to be rectified.
Finally, trusses do not leave a lot of room for future changes, all the pieces are placed in a particular spot for ideal support, taking a piece out or moving something could be detrimental.
Rafters Pros and Cons
Rafters can be a great change even with its differing qualities from the above mentioned trusses.
Attic Space: Rafters offer more attics space as they are an open structure. This means more storage space or even adding an extra room with the open space.
Rafters also give the option of specialized ceilings if desired, this can include a vaulted ceiling or a cathedral ceiling, but those required a lot of additional planning.
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Insulation: When using rafters you can use insulation to create a barrier and help keep the temperature regulated in the home.
Scheduling: Since rafters are built on site, they have less lead time since they do not need much additional planning.
Rafters can be modified as needed the day they are installed as long as there is enough material. This can save a lot of headaches in the long run, and avoid any on road errors that may occur.
There are a few cons that differ from the trusses as well.
Time Consuming/Costs: Rafters are quite time consuming, since it all must be built in real time, on site. This can cause the price of them to go up as well, based on the labor costs.
These labor costs can also be brought up by needed rafter trained craftsmen, who are pretty costly, since it is a specialized skill.
Strength: Rafters are not a strong as its truss competitor, without the extra bracing that the trusses have it can not hold up to as much weight making it the lessor choice.
What Size Lumber Is Used For Roof Rafters
When creating roof rafters one commonly uses 2 x 10 or 2 x 12 pieces of lumber. These then slope down the sides from the central ridge.
It is important that all are the same length or the pieces will not fit in correctly. Rafters have a maximum span of 30 feet. This inhibits the size of the building.
This does limit what the length of the lumber will be though; based on the overall span the roof needs to cover.
The size of the building will greatly affect the size of the materials needed. With the larger materials needed, the costs could be driven up, and also make the installation a little more difficult. Make sure to have any equipment and safety equipment on hand when dealing with larger pieces of lumber.
What Size Lumber Is Used For Roof Trusses
Trusses typically use lumber ranging from 2 x 4 to 2 x 10 depending on the size of the building being built. If it is just a smaller shed, then it will needs something smaller like a 2 x 4.
When it comes to larger homes, they will be more in the range of 2 x 6s and 2 x 8s. Roof trusses can range in sizes and spans so there will be logistic documents drawn out beforehand so that they can be manufacturer according to that.
One of the advantages to trusses is the lower cost, by using these smaller sized pieces of lumber to build the trusses there is the ability to get multiple pieces from the same long piece of lumber.
For example if you have a 2 x 10 you could cut it to get a 2 x 4 and a 2 x 6 if needed. Making sure these methods are utilized in the most effective way can drive cost down exponentially.
Trusses vs Rafters For Load Bearing
One of the most important factors when it comes to deciding which roofing system is needed is how much weight it needs to be able to hold.
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Both trusses and rafters can be load bearing though, seeing as they need to hold up to the elements. One common question to be asked though is, which is stronger?
Are Roof Trusses Stronger Than Rafters?
Yes, roof trusses can hold a great deal more weight than the rafters. Not only that, but they can also span a longer distance and still hold more weight.
Trusses have a webbed look that includes multiple braces strategically placed so that the trusses are stronger and can support the weight of larger buildings as well as any inclement weather or other elements that could add weight to the structure.
Roofs are made to withstand a lot more than they need to, since you cannot predict the future and you most definitely do not want a collapse.
Additionally, these pieces of wood are susceptible to damage, and over time can have a decreased load bearing.
To fully see how much each can hold, there is a roof load calculation that can be done, but it is highly recommended to get a professional to do those calculations and give a formal recommendation on what you should use.
Rafters vs Trusses Cost
When it comes to cost rafters and trusses both have their ups and downs. Weighing the pros and cons between the two can come down to the cost, and from there you can see a clear winner.
Rafters Cost: Rafters, as the most traditional way to frame the roof, requires quite a bit of skill and accuracy.
This type of skill is only had by particular workers, typically older workers who, in recent times, have been retiring.
The demand as well as the skill level needed drives the labor cost of building rafters sky high.
Building rafters on site is not a quick task either. This reason alone is the reason that rafters are the more expensive of the two options.
Trusses Cost: Trusses are a prefabricated product, which means it is built off site and shipped to the location.
At the manufacturing location they knock out a ton of these at a time driving material and labor costs down.
There are shipping costs for the large item, which can be daunting, but in the long run there will be saving to make up for it.
Using trusses ends up being anywhere from 30 to 50 percent less in cost for the roof framing.
In the end trusses are more often used then rafters. Trusses are less expensive to build and provide comparable roof strength.
Two of the main things lacking with trusses is the ability to customize the design and they leave little room for an attic space.
For more related information visit our page on the types of ceiling designs.