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New Roof Installation Process

On this page:
  • Preparing for a new roof installation
  • Hiring a local roofing pro

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The health of your roof can determine the health of the rest of your home. So it is important to understand when to install a new roof to spare yourself from potentially costly problems like flooding and structural damage. A new roof installation is a complicated process, so homeowners need to not only choose their contractor with care, but also should understand the process involved in installing a new roof. Continue reading to learn signs that your roof needs to be replaced, how to choose a contractor, and the steps the contractor will take during the roof installation process.

When is it Time for a New Roof Installation?

If you are not sure when to replace a roof, there are telltale signs you can look for before calling in a professional. The following are some indications that you may need a new roof installation.

roof repair


The age of your roof is a huge determining factor in whether or not you need a new roof installation. Generally, if you have a roof made with asphalt shingles, it can last about 20 years. Meanwhile, a metal roof tends to last a bit longer, ranging from 50 to 80  years when well-maintained. If your roof is reaching the end of its lifespan, it is time to start thinking about installing a new roof to prevent damage to your home.

Damaged Shingles

When your roof is in good shape, the shingles lay flat on top of it. However, if you need roof replacement, the shingles will tell the tale because they will crack, curl, and buckle after years of exposure to the elements.

Leaks and Water Damage

Although you can often tell when to replace a roof by looking at it, sometimes the answer to this question is not actually found there. You may need to check the attic. If there are moisture stains on the walls, paint  peeling on the walls and ceiling, or damp rafters, it could be time for a new roof installation. Leaks and water damage inside your home is also a reason to investigate the integrity of your roof before it leads to structural damage, rot, and other issues. If you are unsure whether a water-related issue calls for an entire roof replacement, be sure to speak to a local roofing professional for advice.

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Moss and Mold

Moss, as well as mold and fungi, can grow on the dark areas of the roof and lock in moisture that causes damage. There may not be any signs of leaks in the attic yet, but the appearance of this unwanted greenery growing on your shingles can be an indication of problems to come.


When boards underneath the roof become rotted, the roof begins to sag. This is a sign that it’s time for it to be replaced, because the damage will only get worse and the roof may eventually cave in.

Step-by-Step Roof Installation Process

Before embarking on a huge home improvement project like a roof replacement, it is very helpful to understand what your contractor will do during the process. Below are the steps a professional will take during the new roof installation.

Roof replacement

1. Choosing materials

Before a contactor gets started on the roof replacement, you will discuss the types of roof materials that will be used. There are several materials to choose from based on the structure of your home, the climate in your location, budget, and your aesthetic.

2. Setting up

One way you can help make the process easier and avoid damage to your property is to set things up before the job begins. You will want to move vehicles, cover landscaping with a tarp, and place garbage cans as close to your house as possible to catch debris.

3. Clearing away old roofing material

One of the most important parts of installing a new roof is removing the old one. If you have an asphalt shingle roof, your contractor will use a shingle fork to pry the shingles off the roof, starting at the top and working their way down. The removed shingles will be put in the garbage cans or dumpsters near the house.

If you have a metal roof, the contractor will use a full-sized pry bar or drill to pry the easterners holding the panels in place loose. Then they will remove the ridge cap and all the fasteners in each panel by working their way from one side to the other. After the panel is completely unhooked, it will be pulled off and set down on the ground. This process will continue until all the panels are removed from the roof.

It is very important that you do not try to remove roofing on your own. Only a roofing professional can ensure old materials are removed properly, without damaging the layers and sheathing underneath. Improperly removing old roofing can add extremely costly repairs on top of the roof replacement.

4. Evaluating the roof

After removing the old roof, your contractor will evaluate the sheathing, which is made up of flat panels that provide structural support and a base for roofing materials, like shingles. Then the contractor will look for any moist areas or trouble spots on the roof that should be replaced.

5. Removing flashing

The flashing on the roof will be inspected after all the roofing has been cleared away. Flashing, which is usually aluminum or galvanized steel, will be installed over joints on the roof to prevent water seepage. This includes the drip edge and any of the flashing at the roof’s valleys, vents, and chimney. If it needs to be replaced, high-quality flashing will be added and then sealed to keep water out.

6. Putting on the drip edge

The drip edge for the roofing goes down in two different parts of the roof installation. For the lower part of the roof, it goes on before the underlayment. For the sides of the roof, it goes on after. First, contractors will install the metal drip edge along the bottom edge of the home over top of the ice and water barrier. It will then be nailed in place flat against the roof.

7. Putting down underlayment

Underlayment plays a vital role in the health of a roof. It catches water and sheds it, so the sheathing and framing below do not get damp and rot. First, your contractor will lay an ice and water barrier, if there isn’t one already there. The contractor will install it underneath the drip edge for added protection, which might mean pulling up the drip edge to install it, then fastening the existing drip edge back down once again. The ice and water shield is nailed down along the edge of the roof for added strength, and the underlayment is installed.

The roofer will begin running the underlayment at the edge of the roof, over the ice and water barrier and the drip edge. It is fastened down with cap nails just above the drip edge. The cap nails are placed every four to six inches along the edge and then spread out around eight to ten inches around the rest of the underlayment.

Then, the contractor will overlap the first row with the next by at least six inches and follow the nail pattern of the first with close nails at the edge, and nails spread out more towards the middle. The same pattern of overlapping and nailing will be continued until just below the roof’s ridge. The underlayment will be finished by running the material over top of the ridge, so it drops down and covers the top edge of both rows of underlayment on either side. Both bottom edges of the underlayment are fastened down firmly. After the roof underlayment is installed, roofers go over it with a drip edge on the sides, which prevents water from running over the edge of the siding and then back underneath it.

8. Installing the new roof

If you are having a new shingle roof installed, the contractor will use starter shingles at the bottom and sides, and stagger each row to keep shingles from leaking water. All the nails holding the shingles in place will be added just under the tar strip on the shingles and installed so no heads are showing.

If you are getting a new metal roof, the roofer starts by screwing up the vertical edge, screwing into each of the ridges rather than the flats. Screwing each vertical row before moving to the next will help the roof flatten. Screwing into the ridges, rather than the flats, will help protect the screws from pooling water, while naturally keeping water away from the fasteners overall.

9. Cleaning up

To wrap up this project, the contractor will clean up any debris that was not already caught in the garbage cans or dumpster. Then, an inspection will be conducted to ensure that the roof was installed properly and the materials are not defective in any way.

How to Hire a New Roof Installation Contractor

A roof installation is a big project, so it is important to choose the right professional to entrust with the job. In order to thoroughly vet professionals before you hire them for a new roof installation, you should do your due diligence by taking these steps.

  • Thoroughly review their qualifications, experience, and licensing
  • Pay attention to online reviews and ask for references 
  • Compare at least 3 different quotes from professional contractors
  • Make sure the quotes are comparable in price and fair
  • Scheduling an in-person appointment to meet with your final choice

Is Your Roof Replacement Quote Fair?

Learn how to evalulate professional roofing contractor quotes and find the best and fairest price for your project

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Finding an experienced roof contractor can take time, but it’s important to give yourself that time to make the right decision. But you don’t have to do it alone; Modernize can help. We have vetted contractors in your local area to help you find the best one for your roof replacement. Start exploring local contractors in your area below.