Replacing a roof is far more than installing new shingles. While this is all that most homeowners will see – the new shingles or metal – some of the most important parts of the roof are the parts you can’t see. The details that have to be done at each stage to ensure the new roof lasts as long as possible with no issues.
There are 8 steps to a roof replacement and each must be followed carefully and done properly. If even one is missing or shortcuts are taken, you can end up with a new roof that constantly has problems and demands your attention. Turning what’s supposed to be a one time investment into a drain on your bank account and a constant stressor.
These are the 8 steps to a residential roof replacement:
- Home Protection
- Removal of Old Roofing Materials
- Decking Inspection & Repairs
- Underlayment Installation
- Roofing Material Installation
- Flashing Installation
- Attic Ventilation
- Cleanup and Final Inspection
Home Protection
When replacing a roof, the process can get messy—fast. Thousands of pounds of old shingles, nails (over 6000 on most roofs!), and other debris will come off your roof, and without proper precautions, this can damage your home and yard.
It’s critical to lay out tarps all around the home to catch all the nails. If the tarps don’t cover everything 100%, you will be finding nails in your grass and landscaping for the next few months. Barriers should be built around any fragile plants or small trees so they don’t get crushed.
It’s best for the old materials to go straight into the dump trailer parked on site, but in some cases this is not possible. If it’s too steep or there’s no access to get a dump trailer close, proper precautions need to be made to get the debris from your home to the dumpster.
For the home itself, protecting the siding, windows, air conditioning units, and other fragile structures (like hot tub covers) from stray nails or heavy chunks of shingles is key. Always ask your contractor: “What’s your plan to protect my property?” A good one will have a clear answer and follow through on that.
Removal of Old Roofing Materials
After the property is prepared for the removal, it’s time to rip off all that old material. The contractor will strip off all the existing shingles, underlayment, and all old flashings and accessories. Depending on the roof’s history, there might be multiple layers of roofing to remove—some homes have had roofs installed over older ones, which means even more nails & shingles. All this waste then will be hauled away, usually in a dump trailer.
It’s critical during this step that all of the existing roofing material is removed, down to the plywood. Some companies, in an effort to save time & money, will leave the old layer of felt on the home. Not only can this hide nails and staples that could be a problem in the future, but it prevents the decking from being seen and inspected, which is a very important step.
Removing the old roof is noisy and dusty, we’ve even found Mt. St. Helens ash hidden in some roofs! Once it’s done the work becomes much cleaner.
Be sure to double check your roof proposal to make sure the contractor has included all existing layers (if you have more than 1) and covers all of the disposal costs.
Decking Inspection and Repairs
Once the old roofing is off, the roof decking—usually plywood or OSB (oriented strand board)—is exposed. This is the foundation for your new roof, so it’s critical that it’s in good shape. A thorough inspection of all the roof decking must be done to make sure there is no rot, water damage, or weak spots.
If they find issues, they’ll replace bad sections, which might mean swapping out a few sheets or, in worse cases, larger areas. This step can add some cost to the project if repairs are needed, but it has to be done – nailing a new roof onto bad decking will cause it to fail long before it should.
Make sure you get the cost to replace decking up front so there are no surprises. This will usually not be included in the original proposal, but as an extra unforeseen cost since it’s hard to know what the decking looks like before the roof is removed. Just be sure to hire a contractor committed to doing this step right.
Underlayment Installation
The underlayment is your roof’s ‘back-up protection’ against leaks. It goes down before the shingles and includes two key players: an ice and water shield (a sticky, waterproof membrane) and synthetic felt paper.
The ice and water shield typically goes along eaves, valleys, and around flashings, chimneys and skylights—all the places prone to leaks, ice dams or heavy water flow.
Synthetic felt covers the rest of the roof, acting as a secondary barrier. This layer isn’t glamorous, but it’s what keeps your home dry during the installation, and afterwards if a shingle blows off in a nasty storm.
Ask what type of underlayment your contractor will use, cheap underlayments (especially ice & water shield) might save money now but won’t protect as well or last as long as the higher quality products.
Roofing Material Installation
Here’s where the new roof really starts to take shape. This step involves laying down the main roofing material—whether that’s asphalt shingles (the most common choice), metal panels, or a flat-roof option like TPO.
Each material has its own installation methods: asphalt shingles get nailed in overlapping rows, metal roofing comes in long panels and needs special screws and trims, and TPO requires heat-welding. The material chosen will affect cost, lifespan, and maintenance—shingles might last 20-30 years, while metal can push 50+.
This is where your contractor’s quality control methods are critical. If the material is not installed according to manufacturer specification, like through improper fastening, it can void your whole roofs warranty and if something were to go wrong in the future you’ll be left holding the bag.
Waterproof Flashings
Flashings are the unsung heroes of a roof – you can’t see much of them but they seal all the joints of the roof where leaks are most likely to occur. This step includes your pipe flashings, wall flashings, valley metal, and any flashings around chimneys and skylights.
This is one of the most commonly overlooked steps of a roof replacement. Some contractors will reuse these to save on costs because it’s hard to tell if new ones were installed after the roof is done. The only way you’d find out is when you have a problem a few years down the road and realize that was the problem.
Getting all new flashings installed is crucial to ensure your roof stays leak free for decades to come.
Attic Ventilation
The final piece of a quality roof replacement is proper attic ventilation. Without good venting, warm, moist air will not be able to escape your attic. This can lead to a host of problems like mold and mildew growth, creating a dangerous environment inside your home. Other issues like wood rot and even insect infestations can happen.
This trapped heat can also bake your shingles from below, leading to early roof failure. If your roof has extreme granule loss before it’s time, it could be because of bad ventilation.
During this step, an intake ventilation inspection is critical to make sure you have proper intake air flow to help your exhaust ventilation (roof vents) be effective. If your intake vent is clogged, there will be no air flow.
Check your roof bid to make sure new ventilation will be added if your roof currently is not up to code. Proper ventilation will keep your attic dry and cool, which will keep your home cooler in the summer and prevent ice dams in the winter.
Cleanup and Final Inspection
After the roof replacement is 100% completed, the last thing to do is a final clean up. Your contractor should clear the debris from your roof, yard, and driveway, along with running a magnetic sweeper to pick up those stray nails (a flat tire from a roofing nail is the last thing you want). If you didn’t get new gutters, existing ones need to be cleaned of old shingle grit and leaves to promote proper water flow.
A final inspection of the roof and all its components needs to be done as well – preferably not by the same guys that installed the roof. Your Project Manager should do this step to double check the work and make sure everything was installed to spec. This is a good time to walk your property with the Project Manager and get clarification about any questions you may have as well.
Finding & Hiring a Contractor
If each of these 8 steps are completed properly, with no shortcuts taken, it’s very likely that you’ve got a new roof that will last for decades with little to no problems. It can be tricky to find a roofing contractor who you’ll be confident will complete all steps. If you’d like some help you can check out our Roofer Hiring Guide that walks you through the best questions to ask a potential contractor.
If you’re in the Spokane or North Idaho areas, give us a call and we’d be happy to discuss your roofing project and see if we’re a good fit. Give us a call at 208-770-9167 to set up a meeting.