The most challenging part of building a house is the roof. However, it can be easy. Start with exact as-built measurements, and then use a calculator to calculate the math. You can cut most roof rafters in one pass.
Ceiling designs are more complex than floor and wall designs. It is because there are many styles, shapes, and weights of roofing materials. Several types of frames are available: gabled, hip, flat, and possibly panned.
Depending on the design of the roof, span, and other components, roof framing might include roof joints, collar ties, and ridge boards. Roof trusses can be roof joists or collar ties. Joists and hanging beams may also use various types and shapes of additional short rafters.
Roof framing’s primary function is to support the roofing material and protect the home.
“When we build, let us think that we build for ever.”
John Ruskin
Parts of a roof
Without a roof, a house or business wouldn’t be as beautiful. To allow your roof to protect your home from the weather and do its job, you must combine the following essential elements in attic structures.
1. The frame of the roof structure
The roof frame’s purpose is to cover the building’s walls and support the roof—the slope allows rainwater to drain from the house.
The roof framework strengthens the structure against winds from different directions. Roof frames come in various styles and can be made from steel concrete or wood.
Purlins, rafters, pitch, and trusses are just a few of the essential components of a roof. The combination of these components forms the roof’s structure.
- Truss
The “skeleton” of the roof is the truss, which is made up of a series parallel beams.
A truss is a triangular unit of straight parts joined at the ends. Prefabricated triangular wooden trusses are used to support the roof. They are designed to support the roof. We can also use them to connect the space above the room.
Trusses are robust and cost-effective, can be made to any size you need, and can span great distances. Trusses transmit all of their weight to the exterior walls. It means that no interior walls are load-bearing.
- Rafter
A rafter can be described as a group of sloping structural members (usually wood beams) that extend from an eave, wall plate, or drop perimeter.
They can support roof decking, shingles, and other roof accessories.
Also known as a stick frame. It is a structure that is built on-site by a professional carpenter. These are the main components of rafters:
- Common rafter
- Plumb cut
- Ridge board
- Collar tie
- Birdsmouth cut
- Tail cut
- Ceiling joist
- Double top plates
- Wall stud
2. Roof covering
The roofing materials are underlayment, decking, shingles, and flashings. These items are necessary for your home to look complete and be as protected as it needs.
- Underlayment can be a waterproof material placed directly on your roof. It can be an asphalt-saturated feeling and placed on the cover.
- Finishing layer on the ceiling. The sheathing consists primarily of plywood or particleboard and is put over the trusses. It is used to strengthen the frame and provide a platform for the underlayment and shingles. In addition, it gives you space to attach the roof covering.
- Decking reinforces the roof structure and provides a base for the tiles. You can make it from many materials.
- Shingles add a beautiful finish to your roof. Many shingles can be used to give your roof a perfect look. There are many options for shingles, including aluminum, galvanized steel, copper, titanium, and many others.
- Flashing is a material that protects areas susceptible to water ingress, such as metal siding around roofs. Flashing can be made from asphalt, clay, metal, wood, or other material. Galvanized steel is the most common roofing material.
It stops flashing water from entering roof joints, holes, and cracks. It top finish adds water protection to the roof and gives it a stunning look.
3. Eaves
Roof ridges are eaves, which are usually located on the exterior walls of a building. It is composed of a fascia and sole with teardrop-shaped edges. This roof is essential as it prevents animal nesting and water ingress.
Ways to frame a roof
There are two ways to build a roof.
Prefabricated trusses or rafters
Truss roofing is today’s most popular type of construction. Roof trusses are sturdy because they have webbing and are less difficult to install due to their factory-made process.
Although rafters give a classic look to new houses, it can be costly and challenging to find an experienced artisan. However, it is also straightforward; one person can cut all the pieces for framing.
Ceiling joists are also known as stick framing
Roof installation is simple with a site-built roofing system. They prevent the roof from spreading and causing it to collapse.
Builders sometimes use this construction method to build cathedral ceilings. However, it is only occasionally simple to construct a stick-frame roof.
Over the years, stick framing requirements have become more complicated. Roof joists are the structural elements to which the roof is attached.
Building triangles with rafters and ceiling joists
The most stable shape is the triangle. The triangle should be kept as straight as possible by attaching the bottom of each triangle to the rafters at the ends. Also, ensure that the floor joists run the entire floor width, so the rafters don’t separate when under load.
- The lower leg of the triangles may be present when floor beams are perpendicular or at a distance from the rafters.
- The lower leg of this triangle might be missing for cathedrals or vaulted ceilings due to the absence of ceiling joists.
Vaulted ceiling
There are two concepts of resistance to the vaulted ceiling’s load. First, to prevent rafter drift at its bottom, rafters that are not supported by bottom ties must be kept at their top ends. Second, the ridge supports half the load. Therefore, the ridge member is now a ridge beam. It is a load-bearing element. It must be designed such that the span between its supports transfers vertical loads to the ground. The ridge beam must be secured to the rafters.
The vaulted ceiling extends from the walls to the middle, creating a lot of space above. It can be attached to walls or floors as a self-supporting fixture.
Types of roof framing
Roofs have different frames, meaning they can drain rainwater differently from their roof surface. The roof’s angle affects the volume available for rainwater outflow. It means that the average precipitation in each case will differ. Flat-pitched roofs may collect 50% more rainwater than flat roofs.
The following five basic structures can be used to frame the roofs:
1. Shed
2. Gable
3. Hip
4. Gambrel
5. Mansard
1. Shed roof framing
A shed-style or pitched roof, also known as a squillion roof or pitched roof, is a roof with a slope in one direction. It is a flat roof that has a steep slope. The pitch of a building will vary depending on its design. Although once used for sheds only, its use in homes is becoming more popular.
The design is easy to implement and very affordable. It’s much easier and quicker for a roofing contractor to design a roof style that requires less labor. It is crucial to properly insulate your roof because It can get very hot or cold depending on the season.
The only requirements for a roof are the rise, span, and line length. Most roofs have a low pitch. It is usually between 4-by-12 (18º), or 8-by-12(33º).
2. Gable roof framing
Gable roofs are A-shaped profiles with two inclined planes equal in length. Gable roofs are made up of pairs of eaves, which run at an angle between the wall and the roof. The basic gable roof assembly is based on a right triangle. The horizontal ridge board (if needed) runs between the pairs at the top.
Gable roofs are the most popular. It is typically 1/4 to 1/3 of the total construction time.
Although the gable design is simpler to construct, it offers limited storage space in the attic.
Storage is fine if there are steep slopes between your trusses or joists. However, the pitch of your trusses or beams will make it more challenging to install the shingles.
Many types of gable roofing have valleys. Many people with roofs with valleys understand that this is the most likely area for a roof to leak.
3. Hip roof framing
A hip roof has a slope at the shed’s sides. They are all equal in length and join together to create a ridge.
A hipped roof does not have gables or any other vertical sides. Hip roofs can be constructed in houses with two trapezoidal and one triangular side. The rectangular plan has a four-sided hipped roof. They almost always have the same pitch or slope, so they are symmetrical around the center lines. A hip roof usually has a constant-level fascia, allowing for gutter installation.
Most hip roof pitch ratios are between 4:12 to 6:12, although there is variation depending on weather conditions, snow, rain, and wind.
First, measure all four walls with a laser rangefinder to measure the dimensions of the frame. Then use a ceiling measuring tool and a rangefinder to measure the ceiling. Second, calculate the length of each rafter. Next, mark and cut the rafters with a saw. Put the rafters together, and then install the rafters. Finally, fix the board to your rafters by nailing them.
4. Gambrel roof framing
Gambrel roofs are symmetrical roofs. Each side has two slopes: one steeper and one shallower. The standard gambrel roof is constructed with an angle 30 degrees and a pitch 60 degrees. However, it is possible to adjust the pitch according to the wishes and needs of the designer.
Gambrel roofs can be built quickly and offer more storage space than traditional pitched roofs. A frame can be constructed from one piece of wood, or you can place the trusses directly on the ground.
Two roof beams are attached to each side of the frame. They are reinforced with simple plates (a triangular metal or wooden plate that strengthens the joints and is usually screwed in). After all the trusses have been installed, they can be lifted onto the roof and secured to the ground. The roof deck can be either timber, metal cladding, or shingles to cover the trunks. The size of the roof will determine the number of trusses needed.
5. Mansard roof framing
A mansard is a quad-sided, barn-like, hip roof. It has two slopes—mullioned Windows perforates one slope at a steeper angle than its counterpart.
A pitched roof with a window creates additional flooring in the dwelling and reduces the overall roof height to accommodate a set number of floors.
Mansard’s roof is steeper and lower than the average roof at 70 degrees. It has an upper slope that ranges between 30 and 36 degrees.
Mansard roofs are available in concave, convex, or straight configurations. The framing style resembles the Gambler’s Roof. We use regular-type rafters. Drill holes and screw securely. Do the same thing again for all sides.
Final words:
In a sense, the roof and four walls provide protection for you and your family. Strong joints such as rafter-to-hip joints or rafters-to-valley joints, rafters-to-ridge joints, and hip-to-ridge joints are necessary for a sturdy roof structure. These connectors enable you to build strong, code-compliant, safe stick-frame roofs by using them together.
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