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When it comes to roof framing for your new home, you can expect to see either rafters or roof trusses. While they may look similar and serve the same purpose, they differ in many ways. Roof trusses have become more popular these days thanks to their versatility, convenience, and lower price point. But rafters (and some types of specialty trusses) offer more attic space if you plan on installing any future conversions. In this article, we’ll dig deep into the differences between rafters and trusses and determine which one is right for you.
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What are rafters and trusses?
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Rafters are long wooden boards used for the frame of the roof, also known as stick framing. Rafters are made on the job site by the roofers and they are typically cut into 2x10 or 2x12 beams, which slope down from the peak of the roof. Ceiling joists then help secure the rafters and the exterior walls. The ridge beam or ridge board is placed at the center of the roof, which helps to support the roof rafters at the top.
Exposed ridge beams in an attic.
It's important to understand the difference between ridge beams and ridge boards. Each requires different sizes of rafters and serves different purposes. The ridge beam is a structural piece that supports and holds up the rafters and is required by building code if your roof slope is less than 3/12. Ridge beams typically offer more stability than ridge boards and lengthen the lifespan of the rafters. They're also commonly used for buildings with vaulted ceilings or when you want to increase the amount of attic space.
Ridge boards are thin, non-structural boards that don't carry the load as well as ridge beams do. These boards serve as a connecting point between the joists on each side and help with the spacing of the rafters as well as the transferring of the load through the joists to the external walls. Ridge boards are typically used for roof slopes between 3/12 and 12/12 and require collar ties to prevent pressure and collapse of the walls, whereas ridge beams don't require collar ties or purlins.
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Roof trusses are similar to traditional rafters in the sense that they provide support but are made and structured differently. Trusses feature prefabricated lightweight wood that's made in a factory, typically from larger pieces of wood like 2x8s or 2x10s, and delivered to the home construction site. While rafters are constructed in a stick framing pattern, trusses feature chords on the top and bottom and an arrangement of webbing which allows them to distribute the load more broadly to the outside walls. There are many different types of roof trusses where the webbing posts are arranged in different patterns, providing different uses. The most basic roof truss is the King Post truss, which requires fewer materials, and costs less than the others.
Rafters vs. trusses: pros and cons
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Pros of rafters
More attic space - Rafters are perfect if you plan on installing any conversions to your attic to make it an active living space. Rafters give you more open space and provide enough room for a loft or a master bedroom.
Insulation - With every roof, you'll want to make sure that your attic is properly insulated. Installing insulation with rafters is easier because of the space between the beams where the installation is installed between the rafters and the drywall.
Less lead time - Because rafters are made on the building site, they require less planning and work than roof trusses.
Cons of rafters
Expensive - While rafters take less time to build and install, the wood and labor costs are typically more expensive than a roof truss system.
Longer construction - Since rafters are built on-site and don't require any prior planning, they are more time-consuming. Rafters, on the other hand, are built ahead of time, so they go up much quicker.
Requires a professional - Since trusses are becoming more popular, more contractors are more experienced with installing them than rafters. Finding craftsmen experienced with rafters can be difficult. Installing rafters is not a DIY roofing project, whereas roof truss DIY kits are available.
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Pros of trusses
High quality - Because roof trusses are made in a controlled environment with precise measurements and cuts, you can expect a higher-quality product and a tighter roof design.
Delivered - Construction projects with roof trusses are easier to plan out because the finished products are delivered to the site.
Faster - While it may take some time to have the trusses made, once they're delivered, building the frame of your roof may only take a few days to complete.
Stronger - Because of the trusses' webbing, it provides load-bearing and can support the roof with cheaper materials.
Cons of trusses
Less space - The biggest downside to roof trusses is the lack of space you'll have. The webbing of the truss makes it virtually impossible to install any conversions, modifications, or any additional space to the room.
Less flexibility - Once a roof truss is installed, you basically won't be able to adjust anything. Any kind of modifications or alterations made to the roof truss will affect the lifespan and structural integrity of the roof structure.
Which one is right for you?
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While they may seem similar, rafters and roof trusses serve different purposes and have many different qualities. Whether or not you have exposed beams, rafters offer a more classic appearance for new houses, but they can cost more, and finding an experienced craftsman may become a hassle. Roof trusses offer more support because of their webbing and are less of a headache to install because of their factory-made process.
At the end of the day, it all comes down to your own needs. If you plan on increasing the amount of room or storage space in your attic, rafters are the right choice. If you’re looking to keep your attic the way it is and want stronger support and quicker roof construction, we recommend installing roof trusses.