Roof Replacement Cost

The cost of a roof replacement depends on various factors that can’t always be easily summed up with an online roofing calculator.

Investing in a new roof not only helps to protect your home from the elements, but it can potentially save you money on energy bills or numerous repairs, as well as boost curb appeal and overall value.

Read on to learn more about 14 key factors that impact the cost of replacing your roof.

14 Key Factors That Impact the Cost of a New Roof

Every roof is unique and requires a trusted, professional roofing contractor to thoroughly inspect and provide an estimate that is specific to your roof’s needs.

While you might want to multiply the size of your roof by an estimated number for the cost of roofing materials and labor, this is an oversimplified calculation that leaves out many critical factors that can impact the total cost of your roofing project.

Roof Size

The size of your home’s roof directly impacts its replacement cost. The more surface area you must cover, the more materials you’re going to need, including OSB/plywood, underlayment, and shingles.

Roof Square Footage

The square footage of your home is not the same as the square footage of your roof, although you can use that figure as a starting point.

Your home’s square footage, frequently listed during a sale or appraisal, is a sum of all gross living areas. It includes each level of a house with multiple stories, but it usually doesn’t account for garage space, basements, and interior walls.

The roof square footage, on the other hand, includes all covered living spaces along with:

You can get a rough idea of how large your roof is in square feet by multiplying the length (in feet) by width (in feet) of all flat planes and adding them together. All measurements should run to the edge of each surface, so that they include any areas that jut out beyond the side of the house (like eaves or overhangs).

Roof Slope

Remember learning how to calculate rise over run in junior high math class? Roof slope is a real-life opportunity to do a rise over run calculation to figure out the incline, or slope, of your roof.

Residential roofs may have steep slopes, low slopes, or a combination of both. Roof slope is expressed either as a ratio or fraction indicating how many inches the roof rises vertically for every 12 inches it runs horizontally (rise/run).

For example, a roof with a 10/12 (or 10:12) slope is much steeper than a roof with a 4/12 (or 4:12) slope.  

In general, the steeper the roof, the more expensive the project cost, and this is typically due to safety reasons. A very steep roof might require special equipment for the roofers to use while they work on it, for instance.

Roof Slope Factor

The slope factor of the roof also contributes to the total square footage. You can determine the slope factor with the aid of a calculator, but roofing contractors typically have slope factor charts that simplify the process.

If you know your roof’s slope, you can find the slope factor using a table or online calculator. If you’re measuring the roof square footage from the ground, then a pitch factor needs to be added.

Pro Tip: You can also order an aerial roof report to get the square footage and slope of your roof from aerial measurement companies.

Waste Factor

Roofing contractors typically add somewhere between 10-15% to the total roof square footage to account for waste factor, but this calculation can vary based on roof style or roofing materials. In roofing, waste factor accounts for material that is overlapped in valleys & hips, as well as cut off material around flashings, penetrations, and gable ends.

Roofing Square

When you work with roofing contractors, you may hear the term “square” being discussed as part of roofing material estimates.

Roof surfaces are measured in squares. A roofing square is an area of your roof that equals 100 square feet and covers a 10’ x 10’ area. The number of roofing squares needed for a project is calculated by dividing the total roof area by 100 (which is 1 square).

For example, if your roof covers a 2200 square-foot area, divide 2200 / 100 = 22, so your project would require 22 squares of shingles to cover your roof.

Roofing Materials

The type of roofing shingles and materials you choose, or may even be required to have installed based on your geographical location and local building codes or HOA rules, will also impact the cost of getting a new roof. For example, traditional three-tab shingles may not cost the same as architectural shingles that also meet COOL roof code requirements.

In addition to shingles, you may also need to replace or install new:

Products within these categories vary in cost due to their own differences in materials, performance, warranties, design or look, and other factors. For example, a roll of synthetic underlayment typically costs more than felt because it is a higher-quality product and covers far more area than a roll of felt.

Depending on the type of roof shingles you choose for your home, a roofing contractor may need to follow special application instructions and/or use specific types of roof components to meet warranty requirements. For example, our Berkshire®, Woodmoor®, and Woodcrest® collections have special application instructions and require specific components to meet warranty requirements.

Roofing Design and Shape

The architectural style or design of a roof will also impact the cost of reroofing. For instance, your roof might have a steep A-frame, multiple dormers, or have a combination of gables and valleys.

A roofing contractor will likely consider the architectural design when providing a roof replacement cost estimate, and you might hear them refer to your roof as “cut-up” — meaning the roof has a more complex construction.

Condition of the Existing Roof

If you need a total roof replacement because your existing roof is heavily damaged, then this may affect the cost as well.

For example, if your roof has a hole in it that requires work on the underlying wood structure, this involves extra labor and materials. Water may have seeped into your attic and upper floors, causing damage that needs to be repaired.

In general, minor roof damage may not be that expensive, but major roof structural damage is likely to be much costlier.

Other Factors to Consider in Roof Replacement Costs

Geographical Area

The area of the U.S. where you reside affects your roofing costs as well. This is primarily because the expense of materials and hourly labor rates are different among geographical regions.

A roof replacement on the West Coast, for example, might not cost the same as a similar job in New England. Additionally, certain areas, such as California and Florida, have specific material and installation requirements to comply with state and/or local energy and/or building codes.

Local Building Permits and Inspections

Many communities require building permits for roofing installation, which must be obtained from the proper municipal authorities. These fees should be factored into an estimate.

In some areas, many inspections take place as the installation progresses, which may add both time and cost to the roofing project.

Roofing Contractor Rates

Roofing contractors typically charge an all-in price per square for a roofing project. This price should include labor and the cost of materials.

To figure out whether rates are reasonable, ask for and compare estimates from several roofing companies in your area, and talk to neighbors, friends, or family who may have had roof work done recently.

Material Disposal Fees

If your roofing project involves removal and disposal of existing roofing materials, then your contractor may add disposal fees onto the total cost of the job. This might involve a dumpster rental if the job is big enough, or might be a general materials disposal fee.

Extended Warranties

Some roofing manufacturers may offer extended warranties for the customer to purchase separately from the standard roofing materials warranty that automatically comes with the products, and this can add to the overall cost of the project.

Ventilation

If it’s determined that your roof doesn’t have adequate ventilation, then installing new vents may impact your roofing project’s costs and timeline. Use our ventilation calculator to estimate your minimum ventilation requirements. Please consult our Ventilation Training Manual for more information on determining proper ventilation.

Roof Repair vs Roof Replacement

When your roofing contractor evaluates your project and provides you with an estimate, they likely will let you know whether or not you need a roof repair or roof replacement.

Some things that might affect their decision include:

Minor or Moderate Damage: Roof Repair

Partial reroofing or repairs may be an option if the physical damage to your roof is mild or moderate. For example, wind damage may have removed several shingles from a certain area of your roof or perhaps the damage is more moderate, but confined to one side of a roof instead of widespread.

In both cases, a roof repair or partial reroof project is likely going to cost less than a total roof replacement.

More Significant Damage: Roof Replacement

If your roofing contractor finds in their evaluation that the damage to your home’s roof is more extensive and/or involves critical structural components, then it might make more sense to get an entirely new roof.

Investing in a complete roof replacement may help you avoid further damage and costlier repairs. Getting a new roof helps to protect your home and your own peace of mind – and you’ll be able to choose a shingle style and color of your choice rather than simply trying to match existing materials.

The Bottom Line

Even if you’ve set the money aside to invest in your home, you may be wondering if you can afford a new roof.

The only way to truly know how much your roofing project is going to cost is to talk to a reputable roofing contractor.

Ask About Finance Options

Fortunately, roof financing options make it easy to get the roof you need without emptying your wallet. Look for loans with low monthly payments, no prepayment penalty, and deferred payments. Ask your independent roofing contractor about finance solutions when requesting your estimate. 

Find a trusted, independent roofing contractor in the Owens Corning Roofing Contractor Network near you. Ask these questions before making your final decision on who to hire.