25 Parts of a Roof (and Their Functions)

Understanding all the different elements that make up an entire roof is crucial when it comes to making effective repairs and maintenance. Like other parts of your house, the roof is complicated and made up of many parts and layers.

In the main, most people would run a mile at the prospect of performing a DIY repair on their roof. However, if you are the adventurous type and fancy giving it a go, this article is for you.

Here is our simple guide to all the parts of a roof with a little background knowledge and what role they play.

1. Shingles

Shingles are flat coverings that protect your roof from water ingress. They are made from various materials, including slate, asphalt, plastic, composites, and metal. Wood is also another widely used material, especially on premium-build homes.

Shingles are ideal if you need to carry out repairs because you only have to replace the broken shingles rather than the entire roof. This is more common than you might think. Shingles suffer at the hands of extreme weather conditions and are susceptible to cracking.

It’s also worth noting that lighter colored shingles reduce what is known as “the urban heat island effect.” Dark roofs can actually increase the heat in the local area in densely populated areas of concentrated housing.

2. Ridge

The ridge of your roof is one of the most important elements. It consists of a horizontal timber sandwiched between the rafters and trusses. It is the roof’s highest point, creating that sloped angle to allow the water to run off.

When the ridge sits between two opposing roof slopes, it is called a duo-ridge, and when it butts to a supporting wall with only one pitch, it is a mono-ridge.

The ridge is the most weather-exposed part of the roof, taking quite a bit of punishment. Interestingly, the ridge board is a non-structural component, serving only as a prop for opposing rafters.

3. Valley

Roof valleys are the point where opposing slopes meet, creating a V-shaped channel for the water to run off the roof. Contractors and roofers are aware that a valley is one of the most problem-prone parts of the whole roof structure.

If you are looking for a leak, the valley is a good place to start your search. Roof valleys can be made from lead, concrete, fiberglass, and even aluminum. Lead is one of the most common materials used in older homes as it is weather-proof and does not corrode.

4. Eave

The eave is the area where the roof extends past the point where the supporting wall ends. It is an essential component of your roof because it stops animals and birds from nesting.

It gets its name from the old English word efes, meaning “edge.”

Some eaves terminate flush with the outer wall, and this is called a “flush eave.” Traditional eaves do a great job of channeling water away from walls, windows, and doors, protecting the exterior of your home against water damage.

5. Soffit

The soffit sits between the outer edge of your roof and the exterior wall. Soffits are both functional and aesthetic in that they form a connection between your roof and the wall and protect against water damaging the wooden rafters inside the structure.

Soffit is derived from the French language and literally means “something fixed underneath.”

Water causes mold and rot, so keeping the wooden elements dry is a crucial job. Not all roofs have soffits, so if you are curious to know if yours does, stand by the exterior wall and lookup.

If the overhang of the eaves is enclosed, that’s your soffit.

6. Rake

The rake isn’t technically part of the roof as it sits on the sloped sides of the gable end to cover where the siding meets the roof. It creates a neat line while protecting the roof from the elements.

Rakes come in three varieties: overhanging and exposed, overhanging and boxed in, and abbreviated or extended. Exposed rakes are more common in older houses like cottages, where the rafters are left exposed beneath the roof covering.

Overhanging and boxed in rakes have a soffit about 6 inches in width to close up any gaps. These are the most common types of rakes. An extended rake has a wider soffit and is usually decorative.  

7. Sidewall

A sidewall is a junction between the slopes of a roof and a wall. The vertical part of the sidewall flashing should extend behind the outside wall to ensure that water does not get in.

8. Flashing

Roof flashing is a thin material, often galvanized steel, that roofers use to channel water away from critical areas of the roof where slopes meet walls, like a dormer.

It is also used to seal the gaps where chimneys, vents, and skylights cut through the roof. Like the valleys, if a problem occurs and you spring a leak, the flashing is an obvious culprit.

9. Hip

A hipped roof is a type of roof where all the sides slope down towards the exterior walls. It lacks a flat gable end or other vertical sides, which is why hipped roofs are typically low-profile with a gentle slope. This slope is referred to as the hip bevel.

For this reason, single-story homes often feature a hipped roof.

10. Flat roof

You might think that flat roofs are roofs with zero pitch; however, they are rarely completely flat, as water needs to drain away. For this reason, they are laid to a fall to allow the water a means of escape.

Flat roofs are a budget-conscious way of protecting against the elements. They are cheaper because they require fewer materials, time, and complex construction. Once you install your flat roof, you can put it to many uses.

You could create a viewing area with railings and seating to take in a spectacular view. You might even want to turn your roof into a garden.

A well-fitted flat roof can last as long as 20 years, and contrary to popular opinion, it can be insulated to avoid heat loss.  

11. Dormer

A dormer is a built-in feature that adds head height to an attic space. It is a window structure that extends vertically beyond the line of a sloped roof. It gets its name from the Latin dormitorium, which means “sleeping room.”

Because it cuts through a section of the roof to gain added height, there are many elements involved when keeping water at bay. Dormers can be made from wood, concrete, or brick and are commonly used when converting attics into rooms.

The dormer roof is laid to fall to allow a smooth runoff for water.

12. Abutment

The abutment is the part where the roof joins a vertical exterior wall. You can buy specialist abutment systems to avoid water leakage.

Another common method is to insert galvanized flashing strips into the adjoining wall and the abutment to create a water-tight seal.

13. Low pitch areas

Low pitch areas are the parts of the roof where the slope is marginal. You might find them on commercial buildings, as well as sheds, outbuildings, sunrooms, and enclosed front doors. The most common material used is a waterproof membrane.

Other materials include sheet steel, aluminum, asphalt, and composites.

14. Downspout

A downspout, waterspout, downpipe, or gutter is a pipe that carries water from your roof via a rain gutter. Downspouts channel water from the top of the building to the ground without dripping or splashing against the exterior of your home.

If you had no downspout, water would overflow the rain gutter and saturate the exterior walls of your house, causing the ground to become waterlogged. This leads to poor drainage, causing damp issues.

On a 1,000 square-foot house, if 1-inch of rain falls, it channels 623 gallons of water towards the downspouts. That’s a lot of water dispersing into the drainage system. In Chicago, the average yearly rainfall is 37 inches!  

That means the average downspout on a single Chicago house contributes to over 23,000 gallons of water soaking away. Now you see why downspouts are crucial to protecting your home.

15. Drip Edge

Drip edges are metal sheets shaped like an L that allows water to get directed away from the roof edge and fascia into the gutter. You find them installed on the edge of your roof, and they are sometimes called drip-edge flashing or D-metal.

16. Fascia

The fascia, or transition trim, sits between the roof and the wall giving your roof that “finished” look. They are both architectural and aesthetic in appearance, neatening the lines between the roof and the exterior walls.

Your gutter sits atop the fascia board as it runs the length of the roof. Most modern fascias are sleek, but they often carry ornate decorations, especially in older homes.

17. Gutters

A rain gutter is sometimes called an eaves-trough, an eaves-shoot, or a water collection channel. It sits on the fascia board along the line where the roof slope extends out over the exterior wall.

Its function is to collect rainwater, channeling it towards the downspout and the ground. As water flows down the slope of the roof, it needs somewhere to go, or you risk saturating the exterior walls of your house.

Common materials used to make gutters include lead, zinc, iron, steel, copper, and painted steel. Rain gutters are problematic because they collect debris like leaves and moss, which inhibits the water flow.

Signs that your gutter needs attention could include damp patches visible on inside walls as well as mold and mildew growth on the exterior walls just below the channel.

18. Rafter

The rafter is one of the main structural components of a roof’s construction. It spans the ridge hip of the roof towards the wall plate of the external wall.

Rafters are laid in sequence, evenly spaced along the roof’s length, and they support exterior coverings like tiles, shingles, and slate. It is important to factor in the weight of the roof covering when constructing the roof.

If the rafters are insufficiently strong enough, the roof may bow and buckle under the weight. Roof rafters are often called roof trusses and are an integral part of the roof’s structure.

19. Underlayment

Roof underlayment is a safety net against severe weather. It consists of a water-resistant material that sits beneath the exterior roof covering.

There are three main types of underlayment:

  • Asphalt-saturated felt.
  • Rubberized asphalt.
  • Non-bitumen synthetic.

Underlayment is not always necessary, especially if you live in areas of low rainfall. However, you should always install underlayment on low-pitched roofs and areas where water ingress could be a problem.

20. Collar beam

Collar beams are one of the simplest forms of roofing and one of the oldest. You often find collar beams in very old houses where the rafters are exposed. Old barns and medieval halls are prime examples of where you might see a series of collar beams.

Imagine the A-frame of the roof, as the rafters run the length of the building. The collar beams sit across the middle, about halfway up the rafters, spanning the gap between the two wooden trusses.

It adds stability, increasing the integrity of your roof’s construction. A collar beam stops the roof from sagging, almost like an additional brace.

21. Chimney

The chimney has one primary function to channel smoke to the outside of your building through a long flue. It also adds stability to the house construction, as it is often the only brick element of the home’s design.

As the smoke draws up the chimney, the air is sucked into the room, fuelling the fire in the grate. It is why you should regularly sweep your chimney to avoid soot build-up, which reduces the strength of the draw and increases the chance of a chimney fire.

You are then in danger of smoke billowing back into the house, causing carbon monoxide poisoning. Chimneys come in all materials like stone, metal, brick, and concrete.

22. Ice and water protector

The ice and water protector is an underlayment membrane that sits below the exterior roof covering to protect it against snow and ice damage. They are typical in buildings situated in colder climates and are often made of polymer modified bitumen.

Sometimes, they are called ice and water shields, as they are a barrier to frost and ice damage that could rot your wooden rafters. Without this membrane, ice forms on your structure, causing expansion and retraction as it melts and dries.

You can imagine that this is not a healthy state for your roof, as wood is susceptible to the elements.  

23. Skylight

Skylight is a generic term for a window in the roof that allows extra light to flood the interior of your home. But there is a difference between a skylight and a roof window.

A roof window is a fixed window to increase light levels in the home. A skylight opens to increase light and airflow. Skylights typically feature in homes with single-story extensions or attic conversions.

Their purpose is to provide light where there was previously none. They also help you take advantage of any nice views, plus they are also a means of escape in an emergency.

Imagine being trapped on the top floor of the house during a fire outbreak. A skylight offers a way out.

Skylights are also a great option when you want to brighten up a darker space and have a limited budget.

24. Lookout

The lookout, or lookout rafter, is a cantilevered wooden joist that extends out from the building’s exterior wall line to support the roof sheathing. It also provides a surface to nail the fascia boards down.

25. Solid decking

Solid decking is the base that forms the “bare bones” of your attic roof and sits on the rafters as a means of attaching a roof covering like shingles or slate.

Sometimes they are referred to as a solidly sheathed deck and form a base to attach roofing materials. Solid decks prior to 1970 typically have between 1 x 8-inch and 1 x 12-inch wooden board decking.

After 1970, plywood became a more popular material. However, unless it is kiln-dried, it will be prone to shrinkage of between 5 and 10 percent, creating 0.50-inch gaps.

Up On The Roof

Are you surprised that there are so many elements that make up your roof? It is one of the most intricate parts of house construction, and yet, we rely on our rooftops to perform so many crucial tasks.

It keeps us dry, warm, protected against the weather, and it makes our homes look good. Plus, without vital components like downspouts, gutters, and drip edges, you risk damage to other parts of your building.