### How do I calculate the size of my roof?

To find your roof’s total square footage:
1. Measure the length and width of each plane on the roof (including dormers) then multiply length times width.
2. Add the square footage of each of the planes together.

### How do I calculate roof covering area?

To calculate your roof area, simply multiply your roof length by your roof slope height, and multiply this by two. This should give you the total area of your roof, not accounting for a chimney or other sections of your roof not covered by tiles. Follow Us for more details Please!

### How do you calculate rafter length?

If you are calculating rafter length from the center of the ridge beam (as shown below), 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.

## Estimate Roofing Costs

Measure the square meter area of the roof you want replaced. The range of prices to replace your roof is: \$50 to \$95 per square meter. So multiple this rate against the square meter of the roof you want replaced.

Average Cost to Replace a Roof
House (& Roof**) by Square FootRe-Roofing Cost*
1,000 (1,054)\$4,000 – \$5,500
1,100 (1,160)\$4,200 – \$6,000
1,200 (1,265)\$4,500 – \$6,500
1,500 (1,581)\$5,500 – \$8,000

### Roof Pitch

Roof pitch (or slope) tells you how many inches the roof rises for every 12 inches in depth. An Example of a roof pitch would be a “6/12 pitch” which means that the roof rises 6 ” for every 12″ inward towards the peak (or ridge). There are two suggested ways to measure a roof pitch.

#### Are flat roofs more expensive?

While flat roofs can cost more than pitched roofs and often require more maintenance, lower-sloped roofs have a clear advantage to homeowners. Flat roofs have large overhangs that do not block light because of their low slope.

#### How much does it cost to roof a 2200 sq ft house?

In general, the replacement cost for asphalt shingles on a 2,200-square-foot home will range from approximately \$8,200 to \$12,000.

### How do I calculate the square footage of my roof?

#### To find your roof’s total square footage:

1. Measure the length and width of each plane on the roof (including dormers) then multiply length times width.
2. Add the square footage of each of the planes together.

#### Most common roof pitch

Conventional slope roofs are most common with residential roofs. This means the slope has a pitch between 4/12 and 9/12 on most homes. Roofs with a pitch exceeding 9/12 are called steep slope roofs.

Footage is Not the Same as Home Square Footage
Depending on where the information is coming from is going to determine the basis on which the estimated roof footage is calculated. The roof square footage is what we (roofing contractor) need to calculate a budget quote to do the job.

### What roof pitch is 30 degrees?

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(angle).
A 7:12 roof pitch means that for ever 12″ of horizontal distance the roof will increase in height by 7″. … The following diagram will let you easily convert roof pitch to degrees; a 7:12 pitch equals 30.26 degrees.

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Conversions Table
10 Square Feet to Roofing Squares = 0.1800 Square Feet to Roofing Squares = 8
20 Square Feet to Roofing Squares = 0.2900 Square Feet to Roofing Squares = 9
30 Square Feet to Roofing Squares = 0.31,000 Square Feet to Roofing Squares = 10

#### How many bundles of shingles do I need for a 2000 square foot house?

The number of bundles or squares you need will depend on the surface area of your roof, and its pitch or slope. For example, a 2,000 square foot roof will require 20 squares or 60 bundles. A professional will likely purchase slightly more materials than necessary to ensure there is extra material if needed.

#### What’s a normal pitch roof?

The most commonly used roof pitches fall in a range between 4/12 and 9/12. Pitches lower than 4/12 have a slight angle, and they are defined as low-slope roofs. Pitches of less than 2/12 are considered flat roofs, even though they may be very slightly angled.

#### Is a 4/12 roof pitch good?

As well, a slope of 4:12 is most commonly considered the lowest slope for “standard shingle installations”. Most manufacturer and industry recommendations require, or at the very least recommend, special underlayment or other considerations on roofs between 2:12 and 4:12.

#### What is a 9/12 roof pitch?

9/12 roof pitch equivalents roof rises 9″ in a length of 12″. 9/12 roof pitch angle = 36.87 degrees.

### How do I calculate how much siding I need?

Start by measuring the height and width of each wall of the building. Multiply each length and height measurement to find the square footage of each wall, then add them together to find the total square footage. Divide the total by 100 to find the number of squares of vinyl siding to order.

A “square of siding” is a measurement of siding material. One square of siding is sufficient to cover 100 square feet of wall space. A square of siding is thus sufficient to cover a 10-foot by 10-foot section of exterior wall.

#### How many square feet does a box of siding cover?

200 square feet

A box of vinyl siding contains two “squares.” A square in construction lingo equals 100 square feet, so a box of vinyl siding will cover 200 square feet. Follow these steps for calculations you’ll use to learn how to measure for wood siding:

1. Measure height and width of each side. For each side, multiply height times width to get the total square feet.
2. Measure other areas not included in the sides, such as gables, dormers and more. For triangle areas, measure from the base of the triangle to the top and multiply that number by half of the base length.
3. Measure the height and width of each window, door and other areas not covered by siding. When in doubt, account for 15 square feet for windows and 20 square feet for doors.
4. Add together the square footage you calculated for the sides of your home and the additional areas.
5. Subtract the uncovered areas’ square footage from the total amount you calculated in step four.
6. Divide this number by 100 to get the number of squares of siding you will need to order.

### How to Measure a Quonset Roof

1. Measure the horizontal width of the Quonset roof to determine the diameter. …
2. Multiply the diameter dimension time 3.14, referred to as “pi,” and then divide the result by 2 to determine the circumference measurement of the Quonset roof. # How to Measure the Roof of a Round Building

1 . Measure the outer diameter of the building.

2 . Measure the amount of horizontal overhang between the building’s outer wall and the roof’s outer edge.

3 . Multiply the amount of overhang by two to include the opposite side of the building.

4 . Add the total overhang to the diameter. For example, a building diameter of 20 feet and an overhang of 1 foot on one side results in a total roof diameter of 22 feet.

5 . Measure the length of the rafters from the peak to the lower edge.

6. Calculate the total surface area of the roof using the following formula: pi times the radius times the rafter length, also called the slant height. To find the surface area using the diameter in the previous example and a rafter length of 20 feet, use the following calculations and use 3.14 as an approximation for pi:

Radius = 22 / 2 = 11.

Surface area in square feet = 3.14 * 11 * 20 = 690.8.

7 .  Determine the vertical height of the roof by finding the square root of the result of subtracting the squares of the rafter length and the radius. Using the previous results, the answer would look like this:

Rafter length squared = 20 * 20 = 400.

Radius squared = 11 * 11 = 121.

So 400 – 121 = 279.

The square root of 279 is approximately 16.7. In this example, the vertical rise of the roof is 16.7 feet from the outer edge to the peak of the roof. # Measuring Roof Slope and Pitch

### Slope

Slope is the incline of the roof expressed as a ratio of the vertical rise to the horizontal run, where the run is some portion of the span. This ratio is always expressed as inches per foot.

### Slope Ratio

A roof that rises 4 inches for every 1 foot or 12 inches of run is said to have a “4 in 12” slope. If the rise is 6 inches for every 12 inches of run, then the roof slope is “6 in 12.”

The slope can be expressed numerically as a ratio. The slope ratio represents a certain amount of vertical rise for every 12 inches of horizontal run. For example, a “4 in 12” slope can be expressed as the ratio of 4:12. A “6 in 12” slope is expressed as 6:12.

### Pitch

Pitch is the incline of the roof expressed as a fraction derived by dividing the rise by the span, where the roof span is the distance between the outside of one wall’s top plate to another.

### Pitch Fraction

Historically the word “pitch” meant a ratio between the ridge height to the entire span/width of the building or ratio between the rafter length to the building width. And back then, the ridge was typically in the middle of the span. This is no longer the case in modern building practices. The ridge can be placed anywhere in the span, from directly middle to either span endpoint.
A roof that rises 8 feet over a 24-foot span was said to have a “1 to 3” pitch. If the rise is 4 feet over a 24-foot span, then the roof pitch was said to be “1 to 6.”

The pitch can be expressed numerically as a fraction. The pitch fraction represents a certain amount of vertical rise over the entire span. For example, given a roof with a rise of 4 feet and a span of 24 feet, the pitch is “1 to 6” pitch, which can be expressed as the fraction of 1/6. A “12 to 24” pitch is expressed as 1/2.

### How Many Roofing Shingles Do I Need?

1. Measure the length and width of each plane on the roof (including dormers) then multiply length times width.
2. Add the square footage of each of the planes together.

The average bundle of shingles covers 33.3 ft2, so three bundles of shingles are needed per square. Asphalt shingles range in price from about \$25 per bundle for a standard 3-tab style to around \$50-\$75 or more for an upgraded architectural style.

### How many square feet does a bundle of shingles cover?

33.3 sq. ft.

Calculating the number of bundles, you need is simple if you are using shingles that come three bundles to a square. Each bundle covers 33.3 sq. ft. of roof area—which is close enough to the 32 sq.

### How many shingles are in a square?

When shingles come three bundles to the square, there are 29 standard-sized shingles (12 in. by 36 in.) in each bundle. Figuring out the roof area is the first step to determine how many bundles you’ll need to order.

## How Shingle Quantities are Measured

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

#### 1. Measurement method

The most accurate way to calculate how many bundles of shingles you’ll need is to get up on the roof and measure each roof plane. If all the roof planes are rectangles, you simply need to multiply the length times the width of each plane to get the square footage; then you will add up the square footage of each plane. Many times, the roof may be too steep to walk on without safety equipment, so you will have to do the estimate from the ground. If this is the case, measure the length of the building at the ground level and estimate any rake-edge overhangs. Next, from a ladder, use a stiff, wide blade measuring tape to measure from the edge of the eaves to the ridge.

#### 2. Sheet-count method

If the sheathing is still exposed you can use the sheet-count method, which is sometimes preferred more than the measurement method. This method is fast, and you can usually complete it from the ground. The caveat is you can use this method only on roofs sheathed with 4x8ft. structural panels. Each of these panels is 32 sq. ft., and you can easily count the full panels from the ground. Another way to tally them up is by estimating the relative size of ripped and crosscut sheets along the edges of the roof to the size of a full sheet. Diagonally cut sheets along hips and valleys are a bit more of a challenge to size, but typically you can assign them a relative size, like half or quarter sheet, and it will be close enough

Calculating the number of bundles, you need is simple if you are using shingles that come three bundles to a square. Each bundle covers 33.3 sq. ft. of roof area—which is close enough to the 32 sq. ft. a sheet covers, which means you can order one bundle for each sheet of roof sheathing.

If you are working with other bundle counts per square, simply divide the number of sheets of sheathing by three and you’ll have the total number of squares needed to cover the roof – this is because three sheets of sheathing equal roughly 100 sq. ft. (one square).

#### 3. Shingle-count method

This method makes it easy to measure when the old shingles haven’t been stripped off yet or if you’ll be doing a layover (meaning shingling over existing shingles).

To start, measure the length of the eaves of each roof plane, either directly from on top of the roof or from the ground by measuring the length of the house and adding in the width of the rake overhangs, if any. Alternately, if the existing shingles are standard three-tab, determine the eaves’ length by counting the number of tabs along the ridges and eaves to determine the length in feet (note that one tab is equal to 1 ft.).

Count the existing courses of shingles from eaves to the ridge to get the length of the rakes. The exposure on each course of shingles is five inches, so multiply the number of courses by five inches and then divide by 12 to get the length of the rakes. Make sure you check that the existing shingles are not metric size and are the standard 12-in. by 36-in. shingles. To get the area in square feet just multiply the length of the eaves by the length of the rake and get the details.

Climbing around on a roof is not safe, so we do not recommend measuring the planes of your roof yourself. Plus, it is important that the measurement is accurate if it will be used to purchase roofing materials. So instead of going to the trouble yourself, contact a reliable roofer for an estimate. The roofer can use professional tools and methods to measure your roof and calculate the total square footage, and then provide estimates for shingles, underlayment, and other materials based on that total.

## How to calculate the roof area

1. Begin with calculating the area of your house in a plane parallel to the ground. If your house is rectangular, all you need to do is multiply the length and width of the building. If the shape of your house is more complex, simply enter the total area (after measuring the exterior dimensions) into the appropriate box.
2. Determine the roof pitch of your house. Roof pitch is the slope created by the rafters. If you don’t know how to calculate it, head to our roof pitch calculator. You can input it either in degrees, as a percentage or as a ratio of x:12.
3. Once you know these values, you will be able to calculate the roof area. Begin by converting the roof pitch to an angle expressed in degrees, using the following formulas:

`pitch(%) = x / 12 * 100%`

`pitch(deg) = arctan [pitch(%)]`

1. Then, use the following equation to find the total area of the roof:

`roof area = base area / cos[pitch(deg)]` ## How to Estimate Roofing Materials

Although roofing projects are estimated and sold by the square, roofing material is often not sold in 1 square increments.

### How Many Bundles of Shingles Will You Need

The average bundle of shingles covers 33.3 ft2, so three bundles of shingles are needed per square. Asphalt shingles range in price from about \$25 per bundle for a standard 3-tab style to around \$50-\$75 or more for an upgraded architectural style.

Since transportation is a major cost factor, expect prices to vary by location. A typical bundle of shingles weighs about 75 pounds, while some premium products can weigh over 100 pounds per bundle, so consider delivery of materials.

### How Many Rolls of Felt Will You Need

Roofing felt is sold by the roll. The average roll of 15-pound roofing felt covers about 400 ft2, or 4 squares, while the average roll of 30-pound roofing felt covers about 200 ft2, or 2 squares.

Rolls of felt are 36″ wide x 144′ long for 15# and 72′ long for 30#. Consider other underlayment options as needed, such as rubber or tar products.

### How Many Nails Will You Need

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. Remember, be wary of too-good-to-be-true estimates that promise cheap and fast results. Investing in name brand materials and quality service will save you time and money in the long run.

## How to measure your roof area from the ground

A more accurate way to calculate the area of the roof than using Google Earth is to get outside to estimate the roof pitch and the base area of the property. Using these two figures, we can get a good idea of the shingle roof’s square footage and estimate your asphalt shingles’ needs and costs. This DIY technique can be helpful, especially if you are not comfortable getting on your roof, or if you have limited access to it.

Ground measures only work well for a gabled roof, since there are usually just two main rectangular pitches to calculate area for. For more complex roof shapes, like hip roofs, you’ll need to work with a roofer or measure from on top of the roof itself to calculate its total area.