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How Do You Measure A Roof Pitch

Is A 3/12 Roof Pitch Good

How to Measure the Pitch of a Roof

Any roofs up to 3:12 are generally considered low slope. In the residential arena, we see lower slope roofs as part of the homes architectural design. Then, when you get into roofs of 3:12 or greater pitch, most other metal roofs can be used and that generally is the pitch requirement for asphalt shingles as well.

How To Determine Your Roof Pitch From The Roof

If you want to measure your roof’s surface, you can think back to algebra class when you learned how to measure a slope as rise over run, the slope is now your roof.

A gable roof style is one of the easiest roofs to measure since it is generally a low pitch that is even throughout the entire house. If you are not a contractor and do not need exact measurements down to the millimeter and degree angle, there is a simple way to measure your roof if you have access to it.

  • A ladder and the ability to safely sit on your roof

Calculate The Roof Area

Now that you have all of your roof measurements, you can calculate its surface area. Simply multiply the length and width of each rectangular plane, and then add the combined area of the hips. Then multiply this number by the roofs slope factor, and then multiply this final result by 1.10 to allow for error.

In this example, our imaginary homes hip roof would cover a surface area of + , while the lean-to roof would be equal to . This gives you a total surface area of 935 square feet. Multiplying this by the slope factor of 1.03 equals 963.05 square feet. Multiply this by 1.10 to obtain 1059.4, which is a good estimate of your roofs surface area.

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How To Calculate Your Roof Pitch From Inside

An easier way to calculate your roof pitch without going on the roof is to measure the rafter length or truss system in your attic. Place your level under the bottom of the rafter, and after the bubble is in the center, mark it at 12 inches. Then measure vertically from the level to the roof rafter. This measurement will tell you the number of inches your roof rises in 12 inches of run.

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How To Figure Out The Square Footage Of A Roof


Repairing or replacing your roof can be expensive, especially if you dont know how to calculate its square footage. A wrong estimate can cost you thousands of dollars and might even delay your roof repair, leaving your home exposed to the elements. The good news is you can easily estimate the square footage of your roof with a few tools and basic geometry.

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What Is The Minimum Roof Pitch

Corrugated roofing is a great material on traditional pitched roofs but it has severe limitations when the pitch gets below 5 degrees. That is why all roofing manufacturers recommend the 5 degree pitch as the minimum slope and they will not provide any guarantees if it is installed flatter than this.

Measuring Roof Pitch Without Maths Using A Roof Pitch Calculator Uk

When learning how to calculate roof pitch in degrees, there are several ways to achieve this. There are a variety of tools available to measure angles without resorting to a tape measure and a calculator. So if you’re looking to learn how to work out pitch of roof installations, the following information can help.

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Calculating Pitch From Slope

  • 1Define roof slope. Most people interested in roof “pitch” are actually measuring the slope, which is the most useful measurement when considering roofing material and rainwater. Slope is the correct term for the ratio of vertical to horizontal distance on a particular plane of the roof. Even carpenters often use the terms slope and pitch interchangeably.
  • For example, if one side of the roof rises by 8 inches for every 12 inches of horizontal distance, it has a slope of “8 in 12” or “8:12.”
  • 2Understand roof pitch. Technically, roof pitch is the ratio of total vertical roof height to total horizontal distance from wall to wall .XResearch source Although most homeowners do not need to measure pitch, it still pays to understand this term. When you’re arranging for repairs or roofing material, your calculations will be way off if you misinterpret “pitch” to mean “slope.”
  • Again, some carpenters and manufacturers use both terms to mean “slope.” Just ask if there’s any confusion about which measurement they’re referring to.
  • For example, if a roof is 32 feet from wall to wall and the ridge is 8 feet above the walls, the pitch has an 8 to 32 pitch, simplifying to “1 to 4” or “1/4”.
  • 3Find the pitch. If you do need to calculate the pitch, an estimate or shortcut is usually more practical than measuring the roof’s overall dimensions. Here are a couple examples:
  • For a simple gable roof, the span will be twice the size of the run . Divide the slope by two to get the pitch.
  • Using A Roof Pitch Calculator

    How to Calculate Roof Pitch

    A simpler alternative to getting out the pencils and paper, there are numerous options both online and as part of smartphone apps that you can use to work out your pitch. To use these calculators, youll need the same rise and run measurements as with manual calculation. Some are more sophisticated and can tell you your roof pitch just with a photo. Our favourite option is VELUXs Roof Pitch app, which is available for both iPhone and Android.

    These calculators do have some drawbacks, however. The photo-based ones can get things wrong if your camera angle or the ambient lighting isnt ideal. The more primitive calculators can also require so many figures beforehand that you might as well figure your pitch out yourself. However, these apps and tools are getting better all the time, providing an excellent alternative to homeowners that may find it difficult to access their roof space.

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    Roof Pitch Calculator Results Explained

    Slope – The slope of a roof is represented as X/12, where X is the number of inches in rise for every 12 inches ofrun. This is very useful information for many purposes, especially for roof framing – the slope, sometimes called pitch, is calibrated on speed squares.

    Angle – The angle of a roof is the same as the roof’s slope, except instead of being represented as X/12, it is represented in degrees. This is useful because sometime you may need to cut a bevel with your circular saw that is not calibrated using roof pitch style – this setting on circular saws is calibrated in degrees.

    Rafter Length – The rafter length results, from this calculator, represents the length of line L on the diagram. Note that this is not the actual length of the rafter. It is the length of this portion of the rafter. If you plan to have overhang, etc. the rafter member will be longer.

    Pitch – Is the incline of the roof represented as the ratio of rise to the span . For example, if the roof rises 4 feet and the span is 16 feet , then the pitch is 4/16, or 1/4.

    Common Rafter Elevation

    If you are calculating rafter length from the center of the ridge beam , you will need to subtract half of the thickness of the ridge beam from the top end of the rafter. For example, if the ridge beam is 1.5 inches thick, subtract 3/4 of an inch from the overall rafter length.

    For more information on roof building, cutting rafters and other design considerations, see the mycarpentryroof framing section.

    What next?

    How Shingle Quantities Are Measured

    Roof shingles are sold by both the bundle and by the square. A square of shingles is the quantity needed to cover 100 sq. ft. of roof. Shingles are packaged in paper- or plastic-wrapped bundles designed to be light enough for a person to carry, so heavier shingles require more bundles per square. Three bundles to a square is most common, which applies to most three-tab strip shingles and some lightweight laminated shingles. Heavier three-tabbed shingles and laminated shingles require four, or sometimes five, bundles to cover a square. When shingles come three bundles to the square, there are 29 standard-sized shingles in each bundle.

    Figuring out the roof area is the first step to determine how many bundles youll need to order. There are two ways to size up a new or freshly stripped roof: the measurement method and the sheet-count method. Theres a third method for calculating bundles when youll be laying new shingles over old or if the old roof is still in place.

    Once you have a bundle or square count for the main roof area, youll add additional shingles to account for waste, starter shingles, and extra shingles for hip and ridge caps.

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    Why Do You Want To Know Your Roof Pitch

    There are a number of reasons you might want to find out how to work out the pitch of your homes roof. For example, you might be installing a new addition, adding more square footage to the roof. In addition, Local zoning laws may require the new roof to meet certain angles, and depending upon which roof pitch you have, certain roof products may not be weather appropriate.

    As a consequence, finding out how to determine your roof pitch in can be very important.

    Four: Measure With A Speed Square

    Sizing Guidelines

    You can also use a speed square and level to quickly measure the roofs pitch. Set the level on the edge of the speed square as shown below, then place the heel of the speed square on a rafter or gable edge of the roof.

    Holding the level and speed square level, locate the measurement on the speed square where it meets the rafters bottom edge to find the angle of the roof in degrees.

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    How To Measure Your Roof With Google Earth

    Using your computer to get a ballpark estimate of your roof area is easy and fast. However, using satellite imagery may not be an ideal solution if your structure is in a very remote location that hasnt been 3D scanned. Thats because well need to grab an accurate representation of your roofs pitch for measuring purposes. From above with a 2D image, everything looks flat. If you were to just measure your roof area from directly above, you wouldnt be accounting for its pitch, or slope.

    Consider two homes with the same base area square footage, but one of them has a much steeper roof pitch than the other. That structure would need to be taller, and there would be a lot more roofing material to account for. If youre just measuring from above in 2D, both of these structures might look identical. If you dont account for roof pitch, youre going to underestimate your materials requirements, which could be a costly mistake.

    Satellite technology has progressed a lot in the past few years. With , you can easily find your address and a 3D replica of your structure, including your roofs pitch. Lets get to it.

    Once you load the site, youll be presented with our beautiful planet:

    While you can switch to 2D mode by clicking the button in the lower right, youll want to stay in this 3D view so you can get a good view of your roofs pitch.

    How Do You Calculate The Slope Of A Roof

    When referring to roofs, the term pitch means two things. Most of the time, people use this term to refer to the roofs steepness. But for carpenters and handymen, they believe that the terms more accurate meaning is the overall dimensions of the roof. Either way, lets see how you can calculate the slope of a roof without using a roof slope calculator:

    1. Measuring the slope from the rafters

    • The most precise way to find the roofs slope is by measuring it from the underside. Access one of the rafters then take the measurement this way.
    • Use a level against the underside of the rafter youre measuring to get the most accurate value.
    • Locate the levels 12-inch mark. If it doesnt have this mark, use a tape measure to locate the mark and draw a mark on it.
    • Take the measurement of the vertical distance from the rafter to the level.
    • Write the slope down using the measurements youve taken.

    2. Measuring the slope from the surface of the roof

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    What Is The Minimum Slope Of A Roof

    The minimum slope of a roof depends on the roofs profile. You need to consider the slope requirements of each panel to determine this minimum slope. The profile is the shape taken by the sheets when you bend them to form panels. Express the slope of a metal roof by a ratio which indicates the pitch of the roof.

    This notes the rise of the roof for every foot of the horizontal run. In other words, you divide the vertical rise by the horizontal run. If youre unsure, you may want to consult with the manufacturer of the panels with the values youve acquired from the roof pitch calculator before purchasing your materials.

    How Many Nails Will You Need

    How to Find the Pitch of an Existing Roof

    Nails will also be required for any roofing project. The average 3-tab shingle needs four nails per shingle. High wind areas and other types of shingles may need more. 320 nails will be needed to install a square of standard 3-tab shingles, assuming four nails per shingle and 80 shingles per square.

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    How To Calculate The Pitch Of A Roof

    Pitch is a measurement of the relative steepness of a roofs slope, and finding the pitch of an existing roof requires only basic tools and simple math.

    Roof pitch is a ratio of a roofs vertical rise compared to its horizontal span. It is an expression of the angle of the roof, and the pitch measurement gives an idea of the relative steepness or shallowness of the roof.

    Understanding The Minimum Roof Pitch

    International building code guidelines recommend a minimum roof pitch of 1/4:12. This means that for every 12 inches of the roof’s runwhich is the horizontal distance it travels as it covers a homethe elevation of the roof should change by at least 1/4 of an inch.

    Keep in mind that the building code requirements for minimum roof pitch may vary from one location to the next. Similarly, maximum roof slope rules can vary by municipality and may be determined by the type of building being constructed. In general, it’s rare for a roof pitch to xceed a 45-degree angle, or a pitch ratio of greater than 12:12.

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    How To Convert Roof Pitch To Degrees

    To find the angle of a roof in degrees, convert the pitch to a slope, then convert to degrees by finding the slopes inverse tangent, or arctangent. First, convert the pitch to a slope.

    To do this, simply convert the rise and run as a fraction to a decimal form, e.g. rise/run = rise ÷ run = slope. For a pitch expressed in inches per foot, convert to a fraction first, e.g. a 4 in 12 pitch becomes 4/12, then divide.

    Next, find the degrees by finding the slopes inverse tangent, e.g. degrees = arctan.

    For example: lets find the angle in degrees for a roof with a 4 in 12 pitch.

    slope = 4:12 = 4 / 12 = .333angle = arctan

    Learn more about finding the angle of a line using our slope calculator.

    Key Terms In Measuring Your Roof Pitch

    How to Measure the Pitch of Your Roof

    Before we proceed, there are key terms that you must understand and some measurements you must learn.

    1. The Rise and Run The vertical distance from one point to the highest point of the roofing is known as rise.

    When you examine a right angle, youll see the vertical component as the rise and then the horizontal component as the run.

    The length of your roof, commonly known as the height, is measured in feet.

    The distance between your roofs peak and the exterior wall is referred to as run.

    2. Roof Angles Roofs come in many different varieties, and depending on your type of roof youll have a slope ratio or pitch fraction thats unique to the condition.

    3. Roof Slope Roof slope is often mistaken for pitch and it is critical to distinguish the significant distinction.

    Slope is the slope of the roof itself and is measured in inches of vertical rise per foot of horizontal length.

    A roof then with a 3-inch rise for every 18 inches of run would appear like: 3:18. The measurement will always be represented in terms of inches per foot.

    4. The Roof Pitch The slope of a roof is referred to as pitch, and it is measured in a fractional ratio of the rise divided by the span, that identifies the distance between exterior walls.

    A roof with a 3-foot rise and a 24-foot span would be a 1/8 pitch of the roof.

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    Start The Project With A Roof Area Calculator

    Calculating the surface area of a sloped roof can be time-consuming without the right tools. You want a roof area calculator that provides accurate estimates to help you order materials such as shingles, membrane, roofing, or ceramic tile.

    Fortunately, if you know the roofs pitch, or have access to the homes attic to measure its incline you can arrive at an accurate roof area calculation using SketchAndCalc.

    Roofing professionals can also use SketchAndCalc to provide fast accurate quotations over the phone. Experts recommend that a pitch measurement is taken before using a roof area calculator.

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