roof diagram

The roof of your home has a variety of different components that have to be able to perform their functions. These components include the rafters, the purlins, the eaves and the chimney. In order to have a good understanding of these components, you’ll need a roof diagram that shows you the location of each piece.


Rafters are an integral part of the roof design. They serve a dual purpose as a structural support for the ceiling and also allow you to turn your attic into a second room.

There are many ways to go about it. A few good examples include the use of construction calculators. Construction calculators are a great way to learn about the various roof systems, without the hassle of memorizing charts.

The top notch construction calculator will provide you with the most pertinent information in a matter of seconds. Unlike charts and graphs, construction calculators are not only pre-programmed with Pythagorean formulas, they are also user friendly. Using one of these is like having a trained salesperson guide you through the process.

If you are unfamiliar with building and maintaining a roof, you may want to consult a structural engineer to ensure your project is designed with your safety in mind. While you are at it, don’t forget to check out the prescriptive code tables. Most codes require a minimum of one half inch of seat bearing on the top plate.

When it comes to rafter construction, there are several factors to consider, but a few are the most important. This includes the material used in the rafter itself and the spacing between rafters. In general, a thicker dimensional lumber will span longer, while thinner boards will give the tiniest of gaps between rafters.


Roof purlins are typically placed along a rafter or truss and are used to support the roof. They help to strengthen the framing of the roof and they may also replace closely spaced rafters in wood frame structures.

Purlins are used in both timber and metal building construction. In wood frame structure, they are typically supported by the rafters, and in metal buildings, they are often placed directly beneath the rafters.

Purlins are usually made from cold-formed steel, which is stronger and lighter than hot-formed steel. However, their load-bearing capacity can be affected by heat production in welding. If welding occurs before the purlin is fully assembled, considerable stress concentrations are likely.

Purlins are available in many different shapes and materials. Some of the most common types include RHS (Right Hand Strut), C purlins, and Z purlins.

RHS purlins are hollow, rectangular tubes with welded ends. They are commonly used as visible supports for the structure, especially for barns.

In addition to providing structural support, they can be painted. A vapor barrier is usually installed on top of the purlins, which provides additional protection against moisture. Steel roof purlins have been introduced to provide a strong, durable alternative to wooden roof purlins.


A soffit is the underside of a building, essentially the area of the roof overhang. It’s the perfect place to cover up the rafters, which could otherwise rot and cause serious structural damage. In addition to protecting your home, a soffit can enhance its appearance.

Soffit is available in a variety of styles, materials, and colors. You’ll want to choose the best option for your home, depending on your aesthetics and the needs of your space.

When choosing a soffit, you’ll also need to consider how you intend to use it. For instance, do you need to hide a structural beam, or will you be using it to provide a hidden vent system? If so, it’s worth considering options such as a vented panel or a solid panel.

The right soffit can make your home look great and protect its components from water and mold. Some structures even use soffits to conceal HVAC ducts. Regardless of what you decide to use, it’s important to properly install your soffit to ensure that your structure will last.

Installing a soffit is a relatively simple process. First, you’ll need to decide what kind of material you want. Vinyl, steel, or aluminum are three of the most popular choices. Choose one that’s light enough for the job but durable enough for your needs.


Guttering is a key part of the drainage system. It is used to channel water away from the home and prevent damage to the foundation.

There are several different types of gutters. They include the fascia, box, and box-type gutters. The most common type is the fascia. It is usually made of Zincalume or Colorbond. Fascia gutters are a popular option for houses with large roofs.

Box gutters are a more common choice on newer buildings. They are designed to blend into the overall structure. However, they are also very effective in draining water.

The ogee gutter is another highly functional and interesting gutter. This design features a curved base and a small lip. It is commonly seen in patios, sheds, and pergolas.

Another important part of a gutter system is the downspout. A downspout is a vertical pipe that leads water from the gutter to the ground. These pipes should be installed properly to ensure the proper direction of runoff water.

One way to determine how many downspouts are required is to estimate the area of the roof. Then, multiply that number by the downspout’s capacity. For example, a 10 foot downspout needs to have a capacity of at least 50 feet.


The eaves of the roof are the edges of the roof which extend beyond the building wall. These are designed to protect the building from water damage and to shield the outside of the structure from the sun.

A typical eave is designed to meet the side of the building at a 90 degree angle. However, some modern houses do not have eaves. Regardless of whether or not you choose to have eaves, the roof’s edges should be finished properly.

Eaves are made of wood. If you want your eaves to look decorative, you may opt for a soffit. Soffits are boards that are installed between the roof edge and the wall. They are used to conceal vents and cable connections.

There are two basic types of eaves: exposed and boxed in. Exposed eaves are the best-known. This is because they do not cover the rafters of the roof. On the other hand, boxed in eaves are more functional. These eaves meet the building at a similar angle as the roof, and they are also covered by fascia.

In general, eaves are used to provide protection from rain and snow. They also direct water away from the siding, window frames, and footings.


Downspouts are vertical pipes that connect to the gutters of a home. They are used to direct water away from the home’s foundation and are a necessity for protecting the home from moisture damage.

Proper downspout positioning will avoid water seepage into the home’s basement. In addition, it will also prevent damage to the roofing and foundation.

The best way to determine how much downspout you need is to calculate the amount of rain falling on the roof. Typically, each square inch of downspout can drain 1200 square feet of the roof. But depending on the intensity of the rainfall, the capacity may be reduced by one-third or even tripled.

There are many styles and sizes of downspouts. The most common style is the corrugated square downspout, which is usually paired with galvanized steel gutters. Its design adds structure to the downspout and is available in a variety of sizes.

Some homes have downspouts directly connected to a storm drain. This can create a bottleneck during heavy storms. If this is the case, the downspout must be capped. Also, the downspouts must be at least 10 feet from the property line.

Ideally, each downspout should have a cross-section area of seven square inches. The end of the downspout should be positioned toward the drainage areas.


When building a chimney, there are many different parts to consider. The diagram below shows the basic components of a chimney. Each part is important in its own way.

The first step is to measure the distance between the top of the chimney and the edge of the roof. This measurement is called the 10′-3′-2′ rule.

The next step is to install the base flashing on the bottom of the chimney. Typically, this is a square piece of metal that is bent at a 45-degree angle. Depending on the slope of the roof, this may need to be bent to fit properly.

To measure the front cap flashing, you’ll need to know the size of the shingle you plan to use for your roof. A typical size is about 8 inches long and fits around the two corners of the chimney. You’ll also need to add an extra 2 inches to the length to ensure it will overlap the lower cap flashing by a few inches.

If your chimney is in need of flashing, you’ll want to start by removing the old roofing material. Use a chisel to remove any old metal and scrapers to remove old mortar. Once the old mortar is loosened, you’ll need to drive the new flashing into the mortar.