Roof Slope Calculator Example Of Use
Measure the run length it is the horizontal distance between the roof ridge and the wall of the building. Let’s assume it is equal to 6 m.
Measure the rise of your roof. Let’s say it is equal to 1.5 m.
Calculate the rafter length, substituting these values into the following formula:
rafter² = rise² + run² = 1.5² + 6² = 2.25 + 36 = 38.25
rafter = 38.25 = 6.18 m
Calculate the roof pitch as the proportion of rise and run:
pitch = rise / run = 1.5 / 6 = 25%
Recalculate this value into an angle:
angle = arctan = arctan = 14°
Finally, you can find the roof pitch in the form of x:12.
x = pitch * 12 = 0.25 * 12 = 3
The pitch of your roof is 3:12. It can also be written down as 25% or 14°.
Using Slope & Pitch Interchangably
Because home construction is now more complex, remodeling as a whole is too! And contractors have been forced to adapt. In doing so, most contractors are now using slope and pitch interchangeably, especially when writing roofing estimates.
When reading about pitch and slope, the most common explanation youll find is actually a hybrid of the two. Youll see a measurement referred to as pitch but the real measurement is slope . Historically, theres a few reasons for this
Measuring Roof Slope And Pitch
Please note that, according to the International Standards of Practice for Performing a General Home Inspection, the inspector is not required to measure the slope of the roof.
GeometrySlopeSlope RatioThe triangular symbol above the roof line in this architectural elevation provides information on the roof’s slope.
- in inches per foot.
Pitch FractionSlope Minimums for Various Roof Coverings
- Asphalt shingles should be installed on roof slopes 2:12 or greater .
- Clay and concrete roof tiles should be installed on roof slopes 2.5:12 or greater .
- Metal roof shingles should be installed on roof slopes 3:12 or greater .
- Mineral-surfaced roll roofing should be installed on roof slopes 1:12 or greater .
- Slate shingles should be installed on roof slopes 4:12 or greater .
- Wood shingles should be installed on roof slopes 3:12 or greater .
- Wood shakes should be installed on roof slopes 3:12 or greater .
- Built-up roofs should be installed on roof slopes 0.25:12 or greater , except for coal-tar built-up roofs that have a minimum roof slope of one-eighth unit vertical in 12 units horizontal .
- Metal roof panels should be installed on roof slopes according to particular seams :
- minimum roof slope of 3:12 for lapped, nonsoldered-seam metal roofs without lap sealant applied
- minimum roof slope of 0.5:12 for lapped, nonsoldered-seam metal roofs with lap sealant applied
- minimum roof slope of 0.25:12 for standing-seam roof systems
Asphalt ShinglesMeasuring SlopeSummary
Also Check: How To Repair A Rubber Membrane Roof
How Roof Pitch Determines Suitable Roofing Systems
Flat and nearly flat roofs cannot be covered with shingles or shakes of any material since there is not enough angle to combat the danger of blow-off. For that reason, flat roofs are limited to these types of covering materials:
Tar and Gravel. Alternating levels of hot asphalt and heavy roofing felt finished with a gravel coating can be applied to a flat roof for protection. Typically, between three and five layers are built up. The cost for this utilitarian roof covering lies mostly in the labor and will vary greatly depending on the location of the building.
For a 2,000 square foot roof expect to pay around $3,500 for materials and supplies and upwards of $9,500 for professional labor. Built-up roofs are not a DIY project and will require professional installation but the waterproofing for flat roofs cannot be beat. A built-up roof can be expected to last 20 years.
Modified Bitumen. Historically, the word bitumen has been used interchangeably with asphalt and tar. It is a naturally occurring goo that develops from millions of years of decomposing organic material and has been used since prehistoric times as a sealant.
In modern roofing, bitumen is infused into plies of polyester or fiberglass to create a weatherproofing roof material. The installation technique is similar to building up with tar and gravel, but the plies are less expensive by half about $2,000 for materials and supplies. Labor is a bit faster and expect a tab of about $8,500.
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.
Recommended Reading: How To Measure The Roof For Shingles
Dont Try To Measure Roof Pitch Yourself
You can read an article or watch a video on how to measure your roofs pitch. This is great for educational purposes, but it doesnt mean you should do it.
If youre not used to climbing a ladder or walking on a roof, youre putting yourself in a dangerous position. Thats why I never recommend getting on your roof to try and measure the pitch.
You also dont know if youre doing it right, even after doing research. While knowing your roofs pitch is important for a roof replacement, its not worth putting yourself at risk.
Wait until you get an inspection by a local roofing contractor to learn the pitch and much more about your roof.
Roof Pitch Angles: How To Calculate Your Roof Pitch
Understanding your new roofs 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. Were here to teach you how to easily calculate and estimate your roof pitch angles manually.
You May Like: How To Patch A Roof With A Tarp
One: Measure From The Roof
One method to find the pitch is to climb on the roof and measure the rise for a 12 run. Youll need a level that is 12 or longer and a tape measure.
On the roof, hold the level perfectly level, and measure the height from the roof to the level 12 inches away from where the level touches the surface this will be the rise.
For example, if the end of a level is 4 above the roof at a point 12 away from where it meets the surface, then the pitch is 4:12.
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:
Also Check: Do All Red Roof Inns Allow Pets
To Measure Your Roof Pitch:
1. Set your ladder on the side of your house so that you can safely access the down slope edge of the roof. You will not need to get on the roof for this step, just make sure that you can touch the edge of the roof from the ladder. As you face the house, the roof should slope up from the left to right, not away from you.
2. Hold a framing square up against the roofline so that the long end of the L points toward the center of the roof and the short end points toward the ground. Essentially, you are forming a right triangle with the long and short sides of the framing square the roof edge forms the third side.
3. Position the framing square so that the long end meets the edge of the roof at the 12 mark.
4. Level the square horizontally.
5. Read the measurement on the short end that is standing up vertically from the roof.
6. :::Remember:::Rise over run. The rise is the measure on the vertical leg the run is the 12 measurement on the horizontal leg. So if the vertical measurement is 6, the roof has a 6/12 pitch.
Roof pitch relates to the slope and inclination angle of a roof in building construction. The primary purpose of a pitched roof is to redirect rainwater. In general, the pitch of the roof is proportional to the amount of precipitation. Houses in areas of low rainfall frequently have roofs of low pitch while those in areas of high rainfall and snow have steep roofs.
Read Also: Can You Use Flex Seal On Camper Roof
How To Find Existing Roof Pitch
Sometimes we need to know our existing roof pitch to install new roofing material or for building inspection. Here are a few methods to easily find the roof slope on your existing shed.
Using 48 Carpenters Level and Measuring Tape
Go on your roof and put one corner of the level on your roof, then bring it up, so it is level with the earth. Lower the measuring tape to the surface of the roof 12 away from where the level meets the roof. The measurement from the roof to the bottom of the level is the rise, over a run of 12.
How to Measure Roof Pitch From Ground
Measure the width of your shed from ground level and divide by two thats your run. For the rise, know that vinyl and clapboard siding typically have 4 exposures before the next course starts above and below it. Find the exposure that is perpendicular to where the roof begins at the side walls of the gable end of the shed.
Follow that exposure to the center of your shed and count the number of exposures until you get to the ridge. Multiply by 4, then divide by 12. You have your rise over run in feet.
Using a Framing Square
On a finished shed, get a ladder and prop it against the slope of one end of roof line. Using a small level atop the flat end of your framing square, put the pivot point against the edge of the roof and bring the square and level up to horizontal with the ground. Use the markings on the square to see where the roof edge lines up with the pitch notations.
Read Also: How To Figure Out Roof Squares
What Is A Standard Roof Pitch
The standard pitch for a residential roof is between 4:12 and 9:12 for most homes. Roofs that go beyond a pitch of 9:12 are steep slope roofs.
At the lower end, you have a 4:12 to 6:12 range. These roofs are fairly easy to both walk and work on, but having safety equipment and taking precautions are important when working on any roof.
A standard roof pitch for a commercial building will have a pitch between 2/12 and 4/12. Commercial building roofs generally have a lower slope than roofs of houses.
A roof pitch that is under 2/12 is considered to be a flat roof. Actually, a flat roof does have some pitch or slope so the roof system has the capability of dealing with drainage. A minimum slope should be at least 1/4 per foot.
How To Calculate Roof Pitch As A Ratio
The traditional method of measuring roof pitch is to display it as a ratio of X:12. This is done by measuring the number of inches a roof rises vertically for every 12 inches it extends horizontally. This is simple to do, and youll need the same tools and access to your roof space as above.
Read Also: How Do I Know If My Roof Needs Replacing
What Slope And Pitch Are
Roof slope and pitch are technically two different things, yet theyre often used interchangeably. Getting an idea of what they are requires some triangular math.
Roof slope is the measurement of your roofs rise compared to the run of your roof. It is expressed as a ratio. For example, if your roof has a slope of 3 feet for every 9 feet of run, its slope is 1:3.
Roof pitch is your roofs rise compared to the span of your roof, and it is expressed as a fraction. The span of your roof is basically the length of your roof . So a roof with a rise of 3 feet for every 12 feet of span would be expressed as 3/12.
By and large, a common roof pitch is anything from 4/12 to 9/12. You can learn more about common measurements by looking at a roof pitch chart.
Estimating The Cost Of The Roof
Once you know the area of the roof, you have to decide on the scope of works. Do you want to build the roof from scratch, or maybe replace the old layers? You also need to decide on the finishing material. For example, asphalt shingles will be less expensive than clay tiles.
After youve made all of these decisions, its best to contact your local contractor and ask about the cost of both materials and labor per square meter or square foot of roof area. Remember that this unit price should include all additional elements such as fasteners, as well as the cost of removing all layers and disposing of them .
The most typical cost of roofing falls between $2 and $4 per square foot . If the price proposed by your contractor deviates from these values, it is advisable to check with other contractors before starting the works.
If you cannot contact any contractor, calculate the cost of materials and multiply this price by 2.5. You will obtain an approximate price including labor, assuming that 40% of the cost is taken by the materials and 60% by the labor.
The last thing you have to do is to multiply this cost by your roof area and voilà, you now know the total cost of your roof! Remember that the real cost might differ from this value a bit due to waste, so plan ahead and assign more funds to this construction work.
Make sure to take a look at our concrete slab cost calculator, too!
Read Also: How Many Squares Is My Roof
What Degree Angle Is A 12 12 Pitch Roof
A 12/12 pitch roof has a pitch angle of 45°. To convert between American roofing ratios and pitch degrees, follow these steps:
Terms For Calculating Roof Pitch
Calculating roof pitch is important to determine the angle of support rafters or trusses. Knowing the following terms makes calculating roof pitch easier.
- Roof span is the width between the exterior walls. Also called the building width, it is measured from the outside surface of the exterior walls, including the sheathing. If the sheathing has not been installed when framing the roof, add a precise estimate to the measurement.
- Rafter run measures the horizontal distance a single rafter must travel and is the roof span divided by two.
- Roof rise is the vertical distance from the center of the span to the roof ridge and is the highest point from ceiling to roof.
- Roof pitch is the angle of the roof based on the rise divided by the run.
Don’t Miss: How Much Does A New Roof Cost In Miami
The Importance Of A Pitched Roof
If a home or building’s roof didn’t have any pitch at all, it would be at a high risk of collecting standing water that ends up deteriorating the roof itself, presenting a serious and inevitable risk of leaking through the roof and into the building. Even on roofs that may appear flat to the naked eye, a slight pitch has probably been built into the roof to facilitate water run-off from rain and snow.
Pitched roofs are even more important in regions where snow can accumulate on a roof. The lower the pitch, the greater the amount of snow that can accumulate on the roof’s surfaceand the weight of this accumulation could potentially break the interior structure of the roof itself. With a higher roof pitch, snow and heavy rainfall can be sloughed off before structural integrity becomes a concern.
Roof pitch can also have the following implications on a home: