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How To Measure Roof Slope

What Roof Pitch Is 30 Degrees

How to determine the slope of a roof

A 30° roof pitch is roughly the same as a 7/12 roof pitch. To convert from degrees to the American ratio:

  • Find the tangent of the angle, tan. This gives you the pitch of the roof.
  • Multiply the pitch by 12 to find the x in the ratio x/12.
  • Check your results with the Omni Roof Pitch Calculator.
  • Enjoy having one less thing to worry about.
  • Gable Roof Sheathing Calculator

    Estimate the amount of plywood or OSB needed for sheathing a roof.The calculation is based on that the Plywood or OSB sheets are of a 4Ⲡx 8Ⲡsize. One sheet = 32 ft²

    This basically calculates the number of sheets needed for a Gable roof.The square footage of a Hip roof area is identical to the square footage of a Gable roof of the same measurements. If you are calculating the number of sheets needed for a Hip roof then for the value of the gable overhang use the eaves overhang dimension, assuming it is the same all around.The amount of waste on a Hip roof will be higher than for sheathing a Gable roof and even more so if you are using OSB sheathing. OSB sheathing has a rough side and a smooth side. You always want to make sure the rough side is up with OSB sheathing. Never install the OSB sheathing with the smooth slippery side up!

    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 = 412 = .333


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    Roof Calculations Of Slope Rise Run Areahow Are Roof Rise Run Area Or Slope Calculated

    • about types of roofing materials, installation, inspection, diagnosis, repair, maintenance, & warranties

    InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

    Roof slope, pitch, rise, run, area calculation methods:

    Examples of simple calculations of stair or roof slope by several methods.

    This article series gives clear examples just about every possible way to figure out any or all roof dimensions and measurements expressing the roof area, width, length, slope, rise, run, and unit rise in inches per foot.

    Page top sketch of various roof slopes is provided courtesy of Carson Dunlop Associates, Toronto.

    We also provide an ARTICLE INDEX for this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

    Standard Pitches: 3/12 Through 9/12

    How To Measure A Roof Pitch

    Standard pitch roofs are the common roofing pitches you’ll find on the main living areas of residential homes. Unlike low slope roofs, areas that have a standard slope can use regular roofing shingles without worry. Because there’s enough of a slope, you don’t have to worry about water drainage as much as you would with something like a 2 over 12 low slope roof.

    In degrees, standard roof pitches are between 14.04 degrees and 36.37 degrees.

    Minimum pitch for shingles

    3 over 12 is the minimum slope a roof needs in order to qualify for roofing shingles.

    Some roofers still opt for low slope materials with a 3 over 12 pitch, but this is not entirely necessary and just adds to the cost of your project.

    Steepest standard pitch

    A 9/12 roof pitch . is the steepest standard slope.

    Anything above a 9 over 12 is considered steep slope.

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    How Various Roof Measurements Are Calculated

    Details for calculating roof area are at ROOF AREA CALCULATIONS

    RA = Roof Area = RW x RL

    If you have safe access to the roof surface you can quickly make the needed area measurements: just measure from the ridge to the lower edge or eaves, keeping your tape straight. With a decent 3/4″ or 1″ wide 30 ft. tape measure you can extend the tape out to catch the roof eaves without having to walk dangerously close to the roof edge. Also measure the roof edge or length.

    • RW = Roof Width – dimension a in my sketch at left. Remember to include in the amount by which the roof extends out over the building walls – its eaves.
    • RL = Roof Length = dimension of the roof from one gable end of the building to the other. RL is simply the building width plus the amount of overhang at the two gable ends of the building.

    Details for calculating the slope, pitch or grade of a roof or any other surface are


    Slope is simply the relationship between increase in height and horizontal distance traveled. In my sketch above if we travel up my triangle along from left to right, we will cross a horizontal distance and we will ascend in height an amount .

    Slope or pitch or grade has several means of expression: Rise/Run, Angle in degrees, Tangent, Pitch, or Percent Grade – all compared in our little table below.

    Tangent = Rise / Run

    E.g. Tan = 1.00 – that is, we will travel 12″ up for 12″ of run

    Below is a tiny summary that shows the range of these values.

    Measure Your Roofs Pitch Today

    Now that youre equipped with the proper tools to calculate your roofs pitch, its time to get measuring! Determine the pitch of your roof with our handy guide and find a local roofer to handle your next roofing project today. provides cost guides, comparisons, and term cheat sheets for hundreds of remodeling, installation and repair projects.

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    Expressing Slope In Standard Pitch

    Note: All of these calculations work the same whether you are using inches or centimeters. You just have to plug the numbers in. A roof that rises 10 cm for every 30 cm of horizontal distance has the same slope as a roof that rises 4 inches for every 12 inches of run.

    In the U.S., the slope of the roof is typically given in standard pitch, which is a ratio expressed as rise-in-run, X-in-12, or X:12.

    Traditionally, 12 is always used as the run, because there are twelve inches in a foot, and you are stating how many inches the roof rises vertically for every foot the roof spans horizontally.

    Pitched roofs commonly have slopes between 4-in-12 and 12-in-12 . A roof that goes up at a 45-degree angle has a slope of 12:12.

    What Is The Best Pitch For A Roof

    How to find Roof pitch or slope

    The best roof pitch depends on the style of roof you are going for. If you are looking for a sleek, modern style, a flat roof with a pitch of 1:40 should be used.

    For a Gothic style, the rafters must equal the span , while an Elizabethan style requires the rafters to be longer than the span.

    In snowy areas, your roof should be at least 10/12 to allow snow to shed, while the safest roof pitch in very windy areas is between 4/12-6/12 .

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    Table Of Correspondences Between And % Of Roof Slope

    This table allows you to obtain:

    • the correspondence of a roof slope in ° or in %
    • the value of the ridge height for a given roof slope for a given horizontal projection.

    The horizontal projection is a half range, i.e. horizontal distance between the centre of the ridge and the outer side of the wall plate.

    What Is The Roof Pitch

    Roof pitch is simply the slope created by the rafter. It can be assessed in two ways either as the angle the rafter makes with the horizontal or the proportion between the rise and the run of the roof.

    Roof pitch is often expressed as a ratio between rise and run in the form of x:12. For example, a pitch of 1:12 means that for every twelve yards of building length, the rise will be equal to one yard.

    We can divide roofs into the following categories:

    • Flat roofs are not perfectly flat in reality they need a small slope for water runoff. Generally, these roofs have a pitch from 1/2:12 to 2:12 .
    • Low pitched roofs have the pitch below 4:12 . These are generally difficult to maintain, as they require special materials to avoid leaks.
    • Conventional roofs have the pitch ranging from 4:12 to 9:12 . They are the easiest ones to construct, and they are safe to walk on.
    • High-pitched roofs often require additional fasteners. They have a pitch that can be as high as 21:12 .

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    Roof Pitch Angles: How To Calculate Your Roof Pitch

    Image source: Action Property Inspections

    Understanding your new roof’s pitch and slope is incredibly important. This helps you understand how excess water, snow, or debris falls off the roof, which also helps guide you to the right type of shingles or roofing materials you need. We’re here to teach you how to easily calculate and estimate your roof pitch angles manually.

    How To Measure Your Roof Slope

    How to convert roof pitch to degrees?

    In order to measure your roof slope, youll need a level and tape measure. Youll want to first measure 12 inches from one end of your level and mark it. While you can measure a roof from the outside surface area, the most accurate way to find your slope is from inside an unfinished attic using the rafters.

    First, youll want to place your level against the bottom of the rafter board. Next, measure vertically from the 12 inch mark on your level to the bottom edge of the rafter. Then, this will give you your rise over run. There are also lots of online roof pitch calculators you can use!

    You can take an in depth look at How to Measure your roof by watching this video:

    If youre ready to move forward with your roofing project, contact a Bridger Steel Product Specialist. Our team of experts can help you choose the right product for your project, and even make recommendations on panel profiles and finishes. Well help you every step of the way from the beginning stages to the final details of your project. Contact Us or fill out the Get a Quote form to get started.

    Check out our Components of a Metal Roof blog to learn more about all the different pieces that make up your roof!

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    Factors Influencing Shed Roof Pitch

    There are tons of reasons to consider when building a shed roof, and the first has to take into consideration the safety of whatever is going to be in your shed. Convenience and interior space are great, but if everything in your interior is wet from leaks, then it doesnt matter how nice your roof looks.

    Understanding The Minimum Roof Pitch

    Internationalbuilding code guidelines recommend a minimum roof pitch of 1/4:12. This meansthat for every 12 inches of the roof’s runwhich is the horizontal distance ittravels as it covers a homethe elevation of the roof should change by at least1/4 of an inch.

    Keep in mindthat the building code requirements for minimum roof pitch may vary from onelocation to the next. Similarly, maximum roof slope rules can vary bymunicipality 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 than12:12.

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    Can You Shingle A 3/12 Pitch Roof

    You can shingle a 3/12 pitch roof, but special application measures should be taken to prevent leakages at some point down the line. Some kind of protective, waterproof membrane should be put down underneath the shingles, as well as using shingles that are recommended by the manufacturer for that slope. You can find this information on the shingle packaging. This issue with these low sloped roofs comes from the flow of water not being quick enough to prevent water from flowing under the shingle and into your ceiling.

    Understanding Roof Pitch Terminology

    How to Measure the Pitch of a Roof

    Are pitch and slope the same?

    Roofing measurements are tricky, especially when it comes to calculating the roof’s incline. You’ve got rise. You’ve got run, slope, span, and pitch! Whats the difference between all these complicated architectural terms? And for the average homeowner gathering roof estimates, do the differences even matter? Keep reading to find out…

  • Exact Examples
  • You can do all the digging youd like for the scientific answers to these contractor debates, but at the end of the day the exact similarities and differences between all the measurements doesn’t matter too much for the average homeowner.

    Whether slope is different than roof pitch or the same doesn’t help you determine how many roof square is on the home so you can order the correct amount of roofing materials. And if you’re a home owner, it doesn’t help you make sense of all the calculations that are jotted down on your roof estimate.

    Some of you may want to know the exact scientific differences, however. So if that’s you, keep reading below. But if you want to know the basic similarities and differences between slope and pitch, you can just click here.

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    How To Measure Roof Slope Outdoors At The Gable End Of A Building

    You need: a tape measure and, if there is no horizontal siding installed, you will need a carpenter’s level.

    From a ladder or other accessible area giving safe access to the sloping gable end trim or roof edges,

    1. Measure out horizontally 12″ from the gable end sloping trim to a point along horizontal siding, or use your level to make a mark that is level, horizontally measured out 12″ from the sloped gable trim or roof edge.

    2. From the point you just marked, measure vertically straight up to the edge of the same sloping gable end trim or roof edge. This distance is the roof rise in inches per foot of run.

    Measuring Slope From The Roof Surface

  • 1Confirm the roof is safe to walk on. Climb up a ladder without your tools to take a look at the roof surface. Do not walk on a wet or icy roof, a very steep roof, or one with obvious structural damage. Even a mild slope can be dangerous to walk on if the roofing material is slippery, gritty , or loose . XResearch source It’s best to walk on a roof when the sun is out and morning dew has evaporated. Never walk directly on a slate roof slates can easily be broken by stepping on them. Special scaffolding equipment is required to safely work on slate roofs, both to prevent damage to slates and to mitigate fall hazard.
  • Curled shingles or other non-flat roof coverings make this method less accurate.XResearch source Consider measuring from the rake board at the edge of the roof instead.
  • Wear clean, dry, basketball shoes or sneakers with soft soles. These have good traction but are less likely to leave footprints on your roof.XResearch source
  • 2Measure 12 inches on a carpenter’s level. Mark the length with the marker. Many levels are equipped with a ruler on the side, but this mark is more visible.
  • 3Organize your tools. Place the level, a tape measure, paper, and pen in a bucket or tool belt. Make sure you can ascend the ladder and move around easily while carrying the tools.
  • It may help to lock your tape measure in extended position before you climb. You’ll only need about 12 inches.
  • Crouch down or sit, as to minimize the potential for slipping.
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    How To Measure Your Roof Pitch From Inside The Attic

    If you cannot access your roof or do not feel comfortable doing so, you can safely measure your roof pitch using the truss structures within your attic by measuring the rafter length.

  • Measure 1-foot from the base of the roof on the attic floor, which is the horizontal run of 12 inches.
  • To find the vertical rise, start at the end of the 12-inch mark measurement, simply measure from the floor to the roof rafter.
  • Using our example measurements from before, say the distance from the floor of your attic to the ceiling is 6 inches, which means your roof pitch is 6/12.

    Slate Roof In Australia

    Roof Trusses and Components Ltd.

    One of the most popular types of roof that is used in Australia is the slates. The slates are made to be attached to the other materials that are used for the roof. These are mostly found in Australia because they can work well with the climate and environment.

    Additionally, slate roofs are most often found in regions that receive heavy snowfall like Scandinavia and Northern Europe. The steep slopes prevent the weight of the entire roof from adding to the pressure on the joints which can lead to damage or leaks after there is a large amount of snow that has fallen on it.

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    Obtain Roof Pitch Or Slope By Using The Rafter Tables On A Framing Square

    A long-standing use of the framing square that is missed by many new carpenters is the rafter table imprinted right on the framing square itself.

    This data will tell us the required rafter length for a roof of a given pitch or slope.

    The rafter table on a typical framing square gives rafter length for roof slopes with a rise anywhere between 2″ to 18″ per foot of run.

    Details of how we use the tables on a framing square to quickly figure out roof slope, rafter lengths, cuts etc. are



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