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November 30, 2021
The Cost of a New Roof: Calculating the Height and Pitch

In our previous post, we shared with you some information about the real cost of a new roof. We also helped to identify how gutters and flashing replacement affects your final budget.

In this article, we’ll show you how to calculate the height and pitch of your ceiling to determine the real cost of a new roof.

The Measurements Needed to Know the Cost of a New Roof

Measuring without climbing

Want to measure your roof? You probably think you need to hop on top of it, but it’s unnecessary. It may not be as accurate as physically measuring your roof, but the results can accurately figure for an estimate.

How to do it?

  • Measure the area of your house’s footprint. Remember to include eaves and other overhangs.
  • If necessary, hang a plumb-bob from the outer edge of the overhang. Then, mark where it touches the ground.
  • Measure the exterior wall of the house. That way, you’ll calculate the length of the protrusion.
  • Now use this measurement to determine its square as above by dividing the total by 100 and round up.


Finding the roof pitch

Now determine the pitch of your roof, which is the measurement of the roof angle’s steepness over a 12-inch run.

  • Measure a 12 inches distance up from the lower edge of your roof.
  • Calculate the number of inches from the suspended end of the roof’s level. Use a level for this task.
  • The result is the pitch of your roof. It is often expressed as “X in 12,” where X represents the distance to the surface.
  • Once you calculate the pitch of the roof, find out how that number impacts your other calculations. The chart below states the multiplier you’ll need:


Pitch Multiply By
2 in 12 1.102
3 in 12 1.134
4 in 12 1.159
5 in 12 1.191
6 in 12 1.230
7 in 12 1.274
8 in 12 1.322
9 in 12 1.375
10 in 12 1.432
11 in 12 1.493
12 in 12 1.554


  • Take the ground level square that you determined from dividing your square feet by 100.
  • Finally, multiply it by the multiplier from the chart above. That way you’ll calculate the total square of your roof.

Still uncomfortable with ladders and heights? You can get the same measurements from inside your attic space by using the beams and trusses as your guides.

However, consider that in low-pitched roofs, it might get uncomfortable. Great, you are one step closer to getting the measurements that will help estimate the cost of a new roof.


Calculating the roof’s height

The roof’s height is essential for both repairs and replacements. For example, extremely tall roofs generate a more dangerous workspace, as well as loose materials that can slide off more easily. Contractors who give estimates over the phone don’t guarantee that estimate until they inspect the actual roof. So, if possible, measure your roof’s height and provide your contractor with more specific information. How to do the math?

  • Calculate the height from the base to the peak of the roof.
  • Now, multiply the roof’s width, as well as the overhangs, by the pitch expressed in a fraction. For instance, 7 in 12 would be 7/12.
  • For a more straightforward calculation, convert the pitch to a decimal. Use your computer if necessary to make sure it’s accurate.

Feeling brainy? Use the top number of the fraction and divide it by the bottom number. Look at the following example:

In the case above, 7 in 12 became 7/12. Seven divided by 12 is 0.58333333333 which rounded is 0.58. If your roof’s width is 100 feet, 100 x 0.58 is 58. So, The height of the roof from base to peak is 58 feet.

Of course, a professional contractor will always want to measure the roof on site. However, by providing this information to your roofer, you can better understand how much work will be involved in taking care of your roof.


Removing old shingles

No matter if you’re a professional roofer or a DIYer, removing the old shingles is the hardest part of the job. The cost of a tear-off varies depending on the area. If you decide to do it as a DIY project, you’ll save about $1,000. However, for effort and safety, it’s always a smart idea to hire a pro.

The following are 8 things to remember when removing old shingles:

  1. Remove shingles safely. Remember to protect the surrounding landscaping as well as doors and windows from falling debris.
  2. Pry shingles up in two- to three-foot-wide sections as you work your way down to the roof. Once you get to the roof jack, return to the top and start over the next part.
  3. When walking over your roof, be wary of hazardous soft spots. If you know the location of the roof supports, stick to those paths, but exercise caution regardless.
  4. Make a plan for shingle debris. Shingles get heavy as they pile up, so start the work on the farthest side of the debris container.
  5. Avoid damaging the flashing. When working near flashing, slow down and take a look at the flashing. If there’s no need to replace it, don’t damage it.
  6. Inspect your roof for underlying damage and nails. Remove them and clean the surface of all the small debris left behind.
  7. Protect roof sheathing and flashing with a water and ice barrier. Be sure to cover all the flashing areas and avoid creating wrinkles in the barrier. Cover the rest of the roof with a 30-pound asphalt-saturated felt.
  8. Clean up your gutters of loose granules and nails. Try running a broom magnet over your yard as well.


Replacing your roof with a different roof type

There are no significant concerns when replacing your roof with another of the same kind. However, if you want to replace a lighter roof, such as asphalt shingles, with something heavier, like slate or clay tiles, you better make sure that your framing can support it. Before using a heavier material, ask a pro to inspect and strengthen your frame and trusses if necessary. That way, you make sure they can support the weight of the new material. Going for a different type will obviously affect the cost of a new roof; keep this in mind.


Replacing a roof is an outstanding job that can lead to all kinds of unexpected complications. Perhaps there’s more damaged timber under your shingles and underlayment than you thought there was. Maybe you find that you have your roof stripped, and there’s no sign of your new shingles being delivered any time soon. These unforeseen problems are enough reasons for many homeowners to hire professional roofers. Given that people always expect a roof to last from 25 years to the life of the building, calling your trusted roofing agency will be well worth it.

Want to know the real cost of a new roof? At Bay 101, we help you determine it. Request a FREE ROOF INSPECTION before it’s too late! Our certified team of roofing experts is willing to help you. Contact us!


Source: https://www.homeadvisor.com/cost/roofing/install-a-roof/
Image credit: Pixabay


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