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How To Figure Roof Pitch

What Is The Best Pitch For A Roof

How to Calculate Roof Pitch

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 .

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 To Calculate Roof Height Over An Attic Floor From Roof Slope & Building Width

In geometry, we learned that if we know the lengths of sides of a triangle, we can calculate its angles.

If we know two of its angles, we can calculate the lengths of its sides.

And for a right triangle, the Tangent function gives some easy calculations of an unknown rise or run if I know the other two figures – the angle and either rise or run distance.

The slope of our example roof is given as 38 degrees.

And we figure that in calculating the “rise” of this same roof, we can assume we are not so stupid as to not hold our tape vertical between the attic floor and the center of the ridge – so we can assume the other known angle is 90 degrees – we’ve got a nice “right triangle”.

If my building width = 30 feet , how much space do I have overhead in the center of the attic? Since our ridge is over the center of the attic that’s the high point.

= = 15 ft. total run or total horizontal distance from eaves to attic center under the ridge.

0.7813 x 15 ft = 11.7 ft total rise across fifteen feet to the highest point in the attic.

Even if I’m Wilt the Stilt Chamberlin I can stand up in the center of this attic. I’m just six feet tall. Never mind Wilt, how far can I walk towards the eaves before I whack my head? We re-use the formula 0.7813= / Run as follows?

0.7813 = / X where X is the run distance from the eaves where I will whack my bean. Rearranging using rules of algebra:

0.7813 x X = 6 ft

X = 6 ft. / 0.7813 = 7.6 ft.

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How To Calculate Roof Pitch As A Percentage

The pitchof a roof can also be expressed as a percentage. A perfectly flat surface has a0% pitch, while a vertical wall has a 100% pitch.

In order tocalculate the pitch of a roof as a percentage, you will need the same tools asfor the previous method: a level, a flat piece of wood and a measuring tape. Proceedas though you are trying to calculate the roof pitch as a ratio, but with anadditional calculation:

* 100 = pitch as a %

That meansthat if you want to express the same 3:12 pitch as a percentage, you wouldcalculate it as follows:

* 100 = 25%

How To Use The Roof Pitch Calculator

Roof Math Formula &  Hip Roof Sc 1 St Planetcalc

This roof pitch calculator or roof slope calculator is a simple, easy to understand tool to use when you need to perform construction work in your home. To use this, you must take the required measurements so you can input them in the required fields. Here are the steps to follow for the roof angle calculator:

  • First, enter the value of the Rise and choose the unit of measurement from the drop-down menu.
  • Then enter the value of the Run and choose the unit of measurement from the drop-down menu.
  • Finally, enter the value of the Rafter Length and choose the unit of measurement from the drop-down menu.
  • After entering all of the values, the roof pitch calculator automatically gives you the values of the Roof Pitch, Roof Pitch , and Roof Pitch .

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How Do You Calculate A Roof Pitch

Roof pitch refers to the slope which the rafter creates. You can assess this in two ways, either as the roof pitch angles which the rafters make with the horizontal or the proportion between the run and the rise of the roof. Often, you express roof pitch as the ratio between the rise and the run in the form of x:12.

You can divide roofs into these categories:

  • Flat roofs which arent perfectly flat require a small slope to allow for water runoff. Generally, such roofs have a pitch ranging from 1/2:12 to 2:12.
  • Low-pitched roofs are generally difficult to maintain and you need special materials to prevent leaks. These roofs have a pitch less than 4:12.
  • Conventional roofs are the easiest to construct and you can walk on them safely. They have a pitch ranging from 4:12 to 9:12. High-pitched roofs often need extra fasteners and their pitch can be as high as 21:12.

You can also calculate roof pitch even without using a roof slope calculator. Use the following formula which also describes a right triangle. Here are the equations you may use to solve for the length of the slope and the rafter:

rafter² = rise² + run² rise / run = pitch, pitch = tan ,

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.
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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.

    Calculating Your Roof Pitch Angles

    How to Find Roof Pitch in Less than a Minute

    By: Author Ryan M.

    Most roofing contractors will just walk onto a roof and take a quick glance at the slope. This is not an accurate way to measure the pitch of your roof.

  • The Importance of Roof Pitch Angles
  • The best way to calculate your roof pitch angles is with a digital level.

    The digital level will allow you to set the roof pitch on a scale divided in half degrees. This should be done at the highest point of the roof and also at where any valleys would be located.

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    Its Time To Get Started

    If you need help getting started calculating the pitch of your roof, schedule a consultation with our team at Legacy Service. We have decades of experience in working with home exteriors, whether it involves roofing and siding or windows and doors.

    We care about the quality of your roof, so our job doesnt just stop when the roofs installation or replacement is finished. Well take care of you and your home from start to finish and communicate with you every step of the way. To get started with your roofing project, contact us here or call our team at 215-798-9790.

    The Importance Of Roof Pitch Angles

    You may be wondering why its so important to calculate your roof pitch angles. Well, a lot of it has to do with the quality of your home and its resale value.

    Its also possible that you could save money on utility bills if you have a more efficient roof, which is all influenced by pitch angles!

    It is much harder to install a new roof on a home that has a low pitch, but with the proper equipment and time you may be able to accomplish it.

    In addition, if your roof is too steep for you, then theres no way that youll be able to do it without professional help!

    Jumping into installing a new roof without calculating the roof pitch angle first can end up causing more headache and money.

    If youre worried about making mistakes and doing it wrong, then hire a roofing contractor to do the work for you.

    Hopefully, weve helped you learn some basics about your roof pitch angles and how to calculate what kind of slope or rise that you have!

    This will be an important step in applying any roofing or shingles that you house.

    Having a good understanding of what your roof pitch is will help you maintain your home and make it more efficient.

    It can also help to add value to the property if you ever consider selling if you are in the buy and well business.

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    How To Find The Tangent Using A Calculator Or A Table

    A tangent is also defined as a ratio of two lengths: the length of the side of the triangle opposite the angle divided by the length of the adjacent side of the angle.

    Watch out: when using a scientific calculator to obtain a tangent value, enter the angle in degrees as a whole number such as 38, not 0.38 or some other fool thing.

    The TAN function or table can be used to convert a road grade or roof slope or stair slope expressed in angular degrees to rise if we know the run, or run if we know the rise ONLY because we are working in the special case of a right triangle – that is, one of the angles of the triangle must be 90deg.

    You can also find free tables of every trigonometric function online, such as a tangent table that will give the value of the tangent for any angle.

    How To Calculate Rafter Length

    Roof Pitch Calculator

    This rafter length calculator lets you calculate roof truss dimensions using two slightly different sets of variables. It all comes down to what information you already have. Usually, that is either the pitch or the rise of the roof. What is more, the formula used to calculate roof truss dimensions is one you probably know very well – it’s the exact same formula you use to describe a right triangle!

    The formulas we used are the following:

  • For calculations based on the roof rise:
  • rise² + run² = rafter length² ,

    meaning that:

    rafter length = .

  • For calculations based on the roof pitch:
  • The formula used to calculate rafter length from roof pitch is, in fact, the same as the one above. The one difference is that we need to calculate the roof rise using the pitch first. So what you need to do first is to get the pitch, using the following formula:

    rise / run = pitch,

    expressed as percents, meaning that:

    rise = run * pitch.

    We can merge these two equations to get a single rafter length formula based on roof pitch:

    rafter length² = ² + run²

    rafter length = ² + run²)

    rafter length = run *

    If you’re unsure about the terms such as roof run and rise, refer to the illustration below:

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    How To Determine Your Roof Pitch The Easy Way

    When you need to determine your roof pitch, all you need is a bubble level and a tape measure. The level should be at least 12 long.

    Step 1: Make sure your have a 12 mark on your level.

    Some levels have markings already and in this case you are ready to go . If you need to make the mark, simply start your measurement from one end of the level. Then put a visible mark at 12. This mark is where youll place the tape measure when youre on the roof.

    Step 2: Climb on the roof and measure.

    Climb up on your roof. Place the end of your level against the roof surface. Hold the level straight and level and then measure the vertical distance down from the your 12 mark on the level down to the roof.

    This is the amount your roof inclines in a 1-foot span or the pitch of your roof.

    Alternatively, if your roof has tile or some other type of irregular material or access is otherwise a problem , you can go up in the attic and do it like this:

    Now that you have the pitch of your roof, write it down on a piece of paper because youll need that information to get your estimate or to order a Roofing Analysis.

    What Is A Roof Pitch Angle

    A roof pitch angle is the angle that the roof makes with a horizontal surface. Roof pitch angles are measured using a common six-step method, expressed in a ratio of 6:12 for steep roofs and 3:12 for low slope roofs.

    Knowing your roofs pitch will allow you to choose the correct type of shingles for your home.

    A steep pitch needs a shingle that is long enough to cover the length of each roofing rafter. A lower pitched roof can accommodate most any type of shingle.

    Measuring the roof pitch angles with a digital level allows one to determine how much work it will take to install an asphalt or fiberglass shingle on your home and sheds.

    If the roof pitch angle is too steep, it might be wise to choose a different type of roofing material or to hire a professional.

    It is critical to understand your roofs pitch and slope before going any further. There are certain ways of how water damage flows into the roof.

    Understanding how it does so may assist you choose the right materials for your roofing or shingles for your home. You must then understand how to calculate your roof pitch angles with no headaches at all.

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    What Is The Standard Pitch For A Roof

    There is no standard, universal roof pitch. Roof pitch varies depending on culture, climate, style, and available materials. In the USA, the range of standard pitches is anywhere between 4/12 and 9/12. In the UK, the typical house has a pitch between 40°-50° although 45° should be avoided.

    Contemporary houses often have flat roofs which shouldn’t be completely flat but should be around 1:40. In Italy, with its more temperate climate, the range of angles is 16-25.

    Understanding The Minimum Roof Pitch

    How to Find the Pitch of an Existing Roof

    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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