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What You Need to Know about Roof Pitch

Published May 20, 2021

Understanding Roof Pitch and Why It Matters

 

How many times does a roof come up in conversations about a dream home?

Let’s face it … not too often, if at all.

People talk about an open concept floor layout, sparkling white kitchens with huge kitchen islands, lavish master suites with state-of-the-art bathrooms, outdoor spaces, and every imaginable part of a home. However, one of the most important features of a home – the roof, particularly its pitch – is overlooked.   

Why should we pay attention to roof pitch? For starters, pitch, or the slant, of a roof is a factor that is critical to many aspects of a roofing system, including the choice of roofing material and accessories such as gutters. Roof pitch can also affect the look of the home. In fact, certain roof pitches (shallow or steep) are integral to some architectural styles.

Because pitch is vital to the roof, its essential to understand its purpose and what it means for the longevity and safety of the structure over our heads.

White Modern Farmhouse with steep gable roof, dormers, and covered front porch

The steep gable roof, dormers, and covered front porch with the white columns all spell curb appeal for this gorgeous four-bedroom modern Farmhouse design. The 4,103-square-foot 1.5-story home has a roof pitch of 1 to 2.4 – meaning that for the main house’s spans 39 feet, the roof rises 16.25 feet – a steep pitch – that adds to its charm and style (Plan #206-1028).

 

What Is Roof Pitch? 

In simple terms, roof pitch refers to the steepness, or the slant, of the roof. It denotes the ratio of the ridge height to the width of a building and is commonly expressed as a fraction. For example, if you want a fairly steep pitch of 1/3 on a roof that 45 feet wide, the roof’s height will have to be 15 feet.

In residential homes, the most common roof pitches range between 1/6 and 1/2. The higher the value of the fraction is, the steeper the roof will be – and the more visually pleasing and appealing.

 

How Is Pitch Different from Roof Slope?   

You may notice that in many instances that the term slope is used instead of – or interchageably with – pitch when describing the roof’s slant. However, they are distinct from each other and don not mean the same things.

  • Pitch is the measurement of the rise of the roof – or ridge height – to the span, which is the distance from one wall’s top plate to another wall’s top plate and stretches across the width of the roof. A roof that rises 5 feet over a 30-foot span has a “1 to 6 pitch,” which can be written as a fraction: 1/6 pitch. A roof that has a ridge height of 10 feet over a 30-foot span has a 1 to 3 pitch, or 1/3 pitch. The larger the fraction, the steeper the roof. Pitch relates more to the actual house construction and is really meaningful only to framers.
  • Slope is the measurement of the rise of the roof in relation to its run, which is the distance from the outside of one wall’s top plate to a point directly below the center of the ridge, and it denotes the number of inches the roof rises vertically for every foot it extends horizontally. For example, a 6 in 12” roof is one that rises six inches per 12 inches of horizontal run. In residential homes, the most common roof slopes range between 4 in 12 and 6 in 12. The higher the first number, the steeper the roof and the more visually appealing it is. While pitch is expressed as a fraction, roof slope is commonly represented in a ratio format – as in inches per foot (3:12, 4:12, 6:12) – or as the phrase “3 in 12,” “4 in 12,” “6 in 12,” and so on. Sometimes you’ll see slope expressed as fraction – 3/12, 4/12, 6/12 – but this is actually incorrect.

In this diagram of a gable roof, you see an illustration of the relationship among rise, run, and span. Visualize the roof slope as a right triangle. See the arrows that mark the run (distance from the outside of the wall) to the vertical rise (the point directly above the end of the run) that form two sides of the right triangle. The roof pitch – on the other hand – measures the rise of the roof to the span (the distance from one wall to another wall) and stretches the across the entire width of the roof. See the arrows designating the span in relation to the vertical rise, or height of the ridge beam (source: International Association of Certified Home Inspectors).

 

Historically, roof pitch is an older term than roof slope and was devised when the ridge of a roof typically came at the center of the span. Over the years, and especially in the past century or so, architects began designing homes and other buildings with asymmetrical roofs, in which the ridge is offset to one side. In these cases, pitch doesn’t apply because it demands symmetry, so the building must be built with two or more pitches, creating confusion. In these cases, and in general when specifying roofing materials like shingles or discussing roof design in general, slope is the more useful term – and concept – to use. This is because there are more – and easier to understand – gradations in roof slope, making specifying materials easier. (See the diagram below.)

This illustration shows the difference between pitch and slope – which can be more finely defined – and why slope is more useful as a design and specifying tool. As you can see, 1/12 pitch = 2 in 12 slope; 1/6 pitch = 4-in-12 slope; 1/4 pitch = 6-in-12 slope; and 1/3 pitch = 8-in-12 slope. But there are many slope designations in between the noted pitches that would be more cumbersome to express as pitch (source: International Association of Certified Home Inspectors).

 

Why Is Roof Pitch – and Slope – Important?

Considered the major component in roof design, the angle of a roof – steep or shallow – has a big impact on the roof’s appearance, durability, and weather performance. It affects drainage, maintenance requirements, walkability, and materials used. Having an idea of roof pitch – but more specifically slope – can help the homeowner make informed decisions regarding the amount of material needed and the type of roofing materials that will work best – and last the longest.

The primary purpose of a sloping roof is to redirect water and snow away from the roof – especially after torrential rain and heavy snowfall. The roof pitch prevents water from accumulating on the roof’s surface, therefore reducing the risk of damage – from mold to leaks, cracks, or the extreme case of a roof collapsing. In areas that are susceptible to a lot of rain and snow – particularly northern states – minimum pitch, or more commonly slope, levels are included in their building codes. And in these regions, the preference is to build homes with steeper roofs.

Contemporary Country style home with steep roof and all-white siding with dark window shutters

This one-story, three-bedroom, two-bath Contemporary Country style design with the steep gabled roof is typical of homes in the New England Region where there is a lot of snowfall and some harsh winters. This home with roof steepness over 1/3 pitch – slopes of 9 in 12 and 14 in 12 – is ideal for that area of the country (Plan #106-1313).

 

Roofing Factors/Aspects

As you get ready to build that dream home, give some thought to your roof choices, the pitch, and the impact on design and aesthetics. There are some factors to think through when it comes to the selection of roof steepness.

 

Climate

Consider the region and local weather. Again, if you live in an area with a lot of snow, rain, hail, and strong winds, a steeper roof can handle these elements much better than lower or medium-pitched ones.

 

Roofing materials are based on roof steepness and water penetration. For example, asphalt shingles are only suited for sloped surfaces because they allow water to penetrate the roof when installed on very shallow planes. In addition to asphalt shingles, high-pitched roofs can have wood shingles and slate tiles.

For low-sloped roofs, choose roll roofing or standing-seam metal, and for flat roofs, choose tar and gravel or rubber membrane.

Modern home with plenty of tall windows that provide lots of natural light and dramatic views

Curb appeal, anyone? A flat shed-style roof adds to the charm of this stunning two-story, three-bedroom Modern home with plenty of tall windows that provide lots of natural light and dramatic views. The roof is made of metal – one of the materials commonly used on low-pitched roofs (Plan #158-1289).

 

Maintenance

Another aspect of roof pitch to remember is maintenance. Every homeowner is aware that roofs require regular maintenance. The frequency, cost, and nature of maintenance requirements are all dependent on roof pitch/practices.

Once again, higher pitched roofs present few drainage problems. However, while tree leaves and other windblown debris accumulate on flat or low-sloped surfaces, shallow roofs are easier to walk on during maintenance and repairs.

 

Attic Space

A pitched roof can increase square footage since it leaves room for an attic or a sleeping loft. Like the basement, the attic is used as extra storage space – and in similar ways, homeowners can be creative with it and design it as an extra bedroom, library, hangout/getaway space, playroom, and more.

If refurbishing the attic is not appealing, think about its other benefits – especially in regulating your home’s temperature. During the summer, attic insulation minimizes heat penetration from outside. In winter, attic insulation prevents heat from “escaping” the house.

Sleeping area in the loft of a rustic cabin style home

This vacation house with country cabin touches is the perfect example of utilizing the space directly under the roof – and converting it into a sleeping area. The vacation home allocates much of the 2,033 square feet of space to the huge kitchen, a spacious family room, two big bedrooms, and two full baths. With its vaulted ceilings and a roof pitch of 1/3 (8-in-12 slope), more room for additional accommodations and a quiet getaway or hangout area is created by making use of the attic/loft (Plan #196-1013).

 

Budget/Costs

Let’s talk about budget and related costs. Because a pitched roof covers more surface area, it requires more roofing material – which means a higher budget and increased costs. Adding to the cost is the trickier design of a roof with a pitch – which raises labor and other professional charges.

 

Other Factors

For rooftop installations like solar systems, roof gardens, and decks/outlooks, a flat or slightly pitched roof is the better choice. You can, of course, have these features – like solar systems – on a steep roof. But why sweat it when it is easier to install them on a flatter roof?

 

Architectural Style and Curb Appeal

It is no secret that houses with steep roofs are more architecturally interesting, unique, and have tremendous curb appeal. Think Victorian, Arts and Crafts, Colonial, Cape Cod, European, French, Tudor, and Shingle Style. Most homeowners prefer the aesthetics of a gable, hip, or even gambrel roof – and like the idea of experimenting with several designs for their roofs.

But there are others who may like the clean and minimalistic lines of contemporary urban buildings. For them, the flat-pitched roof is it. Ultimately, people choose what fits their lifestyles and needs – without losing sight of costs and other practical matters.

Victorian style plan with gable roof covered front and rear porches with decorative elements

This stunning Victorian style plan, with its dramatic gable roof, covered front and rear porches, and the decorative elements adorning the porches, will stop anyone on their tracks. The home’s steep 1/2 pitch (10-in-12 slope) makes it really interesting for those who love unique and architecturally aesthetic features. The two-story Victorian home has 2,590 square feet of living space, three bedrooms, and two bathrooms (Plan #126-1248).

 

Typical roof pitches are grouped into three or four basic categories – from flat to low, moderate, and high slope.

  • Flat roofs, while described as flat, are actually minimally pitched to allow water to drain. A flat roof generally ranges in slope from ½ in 12 to 1 or 2 in 12.

Modern style home with landscaped courtyard, patios, and covered front and rear porches

Heres a vote for the minimalist flat roof. This fabulous one-story Modern style home makes the most of its amazing features: landscaped courtyard, outdoor living space, covered front and rear porches, three bedrooms, 3.5 baths, Great Room, game room, family room, and other amenities under a flat roof made of composite materials (Plan #202-1027).

 

  • Low-sloped roofs – those from 1/12 to 1/6 pitch (or a slope of 2 in 12 to 4 in 12) – are easy to walk on, thus making repairs and maintenance more efficient. But allowing the run-off of rain and snow is a bit more difficult to accomplish.

Mid-Century Modern home with low-sloped metal roof, vaulted Great Room, and an open concept kitchen

Among the features of this amazing two-story, 2,928-square-foot Mid-Century Modern home is an interesting low-sloped metal roof with a pitch of 1/8 (3-in-12 slope), a vaulted Great Room with access to the vaulted covered deck, and an open concept kitchen. The residence includes four bedrooms, three bathrooms, and a walk-out basement with a family room (Plan 108-1923).

 

  • Medium-sloped roofs have pitches of 1/4 (6:12 slope), which is the most common roof pitch. As with everything that is middle of the road. These roofs provide a good balance between ease of access and water and snow runoff.

Contemporary style home with hip roof that has a medium-slope 1/4 pitch

An example of a home with medium 1/4 roof pitch – which is the most common roof pitch – is this attractive two-story Contemporary style house with four bedrooms and 4.5 baths. Within the home’s 5,555 square feet of living space are a master suite with a morning kitchen and his and her walk-in closets, a formal living room and family room, a huge kitchen with a large island, a rear patio with a BBQ area complete with an oven and waterfalls, a swimming pool with its own cabana, and a guest bedroom on the main level (Plan #107-1015).

 

  • Steep-sloped roofs are those designated with very highly angled pitches above 1/3 (generally slopes of 9:12, 10:12, and 12:12 or higher). Because of their angles, these roofs are particularly challenging to walk on and may require extra fasteners.

Victorian style home with gable- and hip-style roofs and a covered wrap-around porch

This two-story Victorian style home with gable- and hip-style rooflines, a covered porch that wraps around three sides of the house, and the elaborate decorative touches on the porch columns has different roof pitches: 5 in 12, 8 in 12, and 12 in 12 slopes for the steepest angle. In addition to the impressive curb appeal of the exterior facade, the home’s interior includes four bedrooms, 2.5 baths, main level laundry, second floor master, home office, and an optional in-law suite with its own private entrance (Plan #158-1235).

 

Common Materials

Shingles and tiles are the popular selections for conventional and steep-pitched roofs (anywhere from 1/6 pitch, or 4:12 slope, and above). They are attractive and perform well.

  • Asphalt shingles are economical, versatile, and work well on most residential roof pitches. They are easy to install, relatively long-lasting and available in a variety of colors and styles.  Asphalt shingles are likely the most affordable roofing option for moderate and steep-sloped roofs – between 50 cents and $1.50 per square foot.
  • While clay tiles and manufactured slate are long-lasting, their disadvantage is their cost and weight. Prices run from $6 to $10 a square foot in most areas of the U.S. – with prices for real slate double these amounts.
  • Concrete tiles can imitate both slate and clay and have prices similar to clay. Concrete, clay, and slate weigh between 900 to 1,200 pounds per square foot – so the roof deck supporting structure must be able to carry the additional weight.
  • Metal can be used in any kind of roof pitch. The common material selections are painted or anodized aluminum and steel. Metal roofs have a long service life and weigh from 40 to 135 pounds 100 square feet, making them the lightest roofing products. Other advantages of metal roofs include easy installation, low maintenance, lightweight, sustainability, and recyclability.

 

While roof pitch does not often figure in conversations about a new home, it is one of its most important structural elements. As you make plans to build your dream home, take the time to learn everything about pitch and slope to understand how it affects the roofing system, the safety – and the look of your home.

 

Footnote: The top left image title montage of this article is a 2,742-square-foot contemporary Farmhouse with four bedrooms and 3.5 baths. For details on the steeply-pitched-roof home with an open floor layout and split master bedroom design, go to Plan #142-1185.

Roof Pitch

Roof Slope

Roof Pitch vs Roof Slope

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