How to Replace a Roof From Start to Finish

Maybe you’ve noticed some broken shingles on your roof, or you’ve recently had a problem with leaks dripping from the ceiling. The elements can do a number on even the best of roofs, and the day may come when you need a roof replacement. While installing a new roof is a complex project that’s not recommended for a typical DIYer, it is handy to know how to replace a roof when you’re hiring a local roofing contractor to do the job for you. Here’s what to expect, from start to finish.

Why Do I Need a Roof Replacement?

Roofs can last 20 to 50 years or longer depending on the material and how well you maintain it, but they experience a lot of wear and tear over their lifespan. From high winds and flying twigs to leaf and snow buildup, the elements can lead to broken shingles, warping, leaks, or mold growth. Roofs keep you and your family safe, but only if they are in good condition. Otherwise, they can cause costly leaks or, in extreme cases, are at risk of collapse.

How Much Does It Cost to Install a New Roof?

A new roof or a roof replacement costs an average of $9,000, or around $5,700 to $12,300. About 40% of the total cost goes toward materials. This is a dangerous job that requires a lot of advanced skills, so you’ll be paying about 60% of the project total for labor. Each roofing square, which is about 100 square feet, costs $150 to $1,500 just for the materials.

Signs It’s Time for a Roof Replacement

There are several signs it’s time for a roof replacement to keep an eye out for, especially if you have a roof over 20 years old. Here are some key symptoms of a roof that needs to be replaced:

• The roof’s life expectancy is coming to an end.

• You notice damage, like broken or warped shingles or cracked roof tiles.

• The roof is sagging or feels bouncy to the touch.

• The roof's flashing, which protects against water leaks, is damaged.

• You have leaks or can see sunlight through the attic ceiling.

How to Replace a Roof in 9 Steps

Photo: vitranc / iStock / Getty Images Plus / Getty Images

Replacing a roof requires several meticulous steps, but skilled contractors will be able to complete the work in as little as one day.

“When going through roof replacements many contractors have different ways to handle their replacements, however the steps mentioned here are followed by most reputable roofing contractors,” said Eric Gonzalez, Expert Review Board Member and Founder of Regions Commercial Roofing, Inc.

1. Remove Old Roofing Materials

While you can install new shingles over the old ones, this provides a less stable and secure roofing surface. Instead, the contractors will use a roofing shovel to carefully remove the existing roof material, then dispose of it in a roll-off dumpster bin. This is one of the most challenging parts of the job, so if you do have the skills for a DIY, consider hiring a pro for this step at a minimum.

2. Make Repairs as Needed

For extremely old or heavily damaged roofs, the contractors may need to repair the frame or add new sheathing to give the new roof material a sturdy, long-lasting base. It's never okay to simply cover up a damaged roof with new roofing material. This won't fix the problem and will likely make it worse.

3. Add the Drip Edge

You may not need a metal drip edge, but this material will keep water from running on the fascia boards along the roof.

• Place the roof drip edge tightly against the fascia boards.

• Use roofing nails through the decking to secure the drip edge.

• Place roofing nails every 2 to 3 feet.

4. Install Water and Ice Barriers

A water and ice shield or barrier is required in some locations, especially if you live somewhere with harsh winters. If you want to save money on costly water damage down the line, this step is crucial. 

These barriers, sometimes called ice and water underlayment, will keep water and ice from damaging the roof sheathing, and they need to be installed on roofs with 2/12, 3/12, or 4/12 pitches and around any roof’s valleys. The contractor will install the water and ice shield around the edges of the roof to protect against ice dams and water damage.

5. Lay the Roofing Paper

Once the underlayment is installed, the contractor will begin laying roofing paper, overlapping toward the roof peak for protection against moisture and fire. The roofing paper is nailed or stapled to the roof sheathing at least every 12 inches.

6. Protect From Leaks With Flashing

When it comes to a roof, it’s all about leak protection. From the ice shield to the roofing paper to the flashing, keeping water from penetrating the roof sheathing or the interior of your home are important. Otherwise, the damage could be expensive. The contractor will nail metal flashing in the valleys of the roof and seal them with caulk for the best protection.

7. Bring in the Shingles or Other Roof Materials

With the proper protection against the elements in place, you can finally start to see your new roof materialize as the new roofing material is installed. The contractor will start applying shingles or roof tiles at the ends of the roof, near the eaves and metal drip edge, then will work upward toward the peak of the roof.

8. Finish With the Ridge Vent

You’ll want to install a new ridge vent if your roof doesn’t already have one. Some of the pros of ridge vents include helping prevent ice dams and improving air circulation in the home. With a new ridge vent installed or when you’re ready to add roofing to an existing ridge vent, the contractor will first add flashing around the vent before shingling around the ridge vent.

9. Get an Inspection

Because roofs are so important to our safety, you’ll need to clear up the work site and have a building inspector take a look at the completed job. With a roof inspection and sign-off of approval, your new roof is ready to shelter your household.

Taking Care of a New Roof

A little DIY roof maintenance goes a long way in helping your roof stay in great condition for many years to come. 

Trim Trees

All it takes is one wind storm for tree branches to damage your roof. Not only that, but branches that come right up to the roof make a handy bridge for neighborhood pests, like squirrels or raccoons, to access your home. To protect your roof, make sure trees are trimmed back at least a few feet from the exterior of the house.

Clean the Gutters

Without clean gutters, water can’t drain properly away from the home. When it comes to how often to clean gutters, plan on doing this chore at least twice a year, although you may want to clean them every season. If you dread cleaning the gutters, you can also hire a gutter cleaning service to handle this job for you.

Clear Away Debris

Aside from fallen leaves in the gutters, any debris on the roof can lead to trouble. From snow to twigs, make sure to clear off the roof to prevent mold and moss growth.

• Use a snow rake to clear away heavy snow buildup.

• Carefully clear away leaves and twigs by hand.

• Hire a local roof cleaner to clean up any mold, moss, or algae.

Schedule a Yearly Roof Inspection

Your roof needs a professional roof inspection at least once a year to catch any problems as early as possible. You can also perform DIY inspections without getting on the roof every season or after a big storm to look for damaged shingles, debris, leaks, or mold growth.

DIY vs. Hiring a Roofing Contractor

Building your own DIY roof will cost about $2,500 to $6,300 for the replacement materials. For the vast majority of homeowners, this project is best left to a professional. While hiring a professional roofing contractor will bring the project total to around $5,700 to $12,300, the investment is worth it. Roofing is a dangerous job, and you’ll need to obtain specific permits to do the work.

If you make any mistakes, they could be costly. Professional work typically comes with a warranty and may even be covered by your homeowner’s insurance, but DIY jobs usually don’t come with these same financial protections and benefits.