Most standard asphalt shingle roofs are torn off, installed and fully replaced within a single day. Because most roof installations happen over the course of a few hours, many homeowners don’t know what to expect during the process or how it all works. There are steps that our certified roofing contractors will take to ensure that your installation will be completed without error to provide the highest quality roof replacement out there.
Your standard roof installation will happen in 10 steps.
- Roof tear down
- Drip Edge Installation
- Ice & Water Shield Underlayment Installation
- Underlayment installation
- Valley Waterproofing
- Starter Shingle Installation
- Asphalt Shingle Installation
- Step & Dormer Flashing Installation
- Ridge Capping
- Sealing

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Step 1: Roof Tear Down
There’s no way around it: the old roof has to come off. However, that doesn’t mean that literally your whole roof is coming off the house. Most roofs have a few basic layers of protection: The decking (usually plywood) is at the bottom. Underlayments (basic waterproofing and protection for the decking) are on top of the decking. Then Shingles and Flashing (what you actually see on the outside of a roof at the top layers).
The first step is straightforward: all the old asphalt shingles, underlayment and flashing is removed off the roof, leaving the plywood decking underneath exposed and ready for new protection layers.
After the old materials have been torn away, this will expose any weaknesses in the decking itself (such as any holes or moisture damage previously unknown) and decking can be replaced as needed with brand new plywood. This is done in order to guarantee the longevity of the new roof.
Step 2: Drip Edge Installation
Before any shingles are put into place, the very first thing to go in is the new drip edge.
Drip edge is the little metal strips that you can usually see on the edge of your roof line and they prevent shingles from curling, keeps water away from the fascia and gives the roof edge a nice polished finishing look. These are cut into smaller pieces and run up and down along the outer edges because most roofs aren’t perfectly straight, so the drip edge has to be molded to perfectly run alongside your roofs subtle contours.
Step 3: Ice & Water Shield Underlayment Installation
Underlayments are barriers made of waterproof materials (we use all synthetic underlayments at Infinite Roofing) that get attached directly to the roof decking. More heavy duty underlayments, often called ice and water shields, are placed around the bottom edges (near your gutters) for a standard of 6 feet.
6 feet is laid down because here’s what happens over time with your roof: heavy winds blow rain water under shingles, in winter ice dams (usually caused by poor attic insulation) form on the roof, and they work there way up underneath the shingles. This is where most leaks are caused. Heavier ice and water underlayments prevent this from happening because they stick directly to the plywood decking and seal out any water that might otherwise seep into your attic. A side benefit is they also form seals around nails to prevent any water leaks through nail holes that form during the shingle installation process.
Step 4: Primary Underlayment Installation
With the water and ice shield in place, the next step is to cover the rest of the roof with synthetic underlayments - although this variety doesn’t need to be as heavy duty as the underlayments that are near the bottom edges of your roof.
The reason two different materials are used is to reduce cost and also because you simply don’t need ice and water shield grade underlayment coverage over your entire roof - those are designed for “high traffic” areas that see the most abuse (where water and snow is going the most, near the gutters). For the rest of the roof, standard synthetic underlayments will provide 20+ year protection without any problems.
Every square foot of the roof is covered with this underlayment in order to waterproof the decking and protect your investments longevity.
Step 5: Valley Waterproofing
Roof “Valleys” are where two sections of roof meet each other, creating a valley or channel. These are significant because they attract a lot of water. Most roofs are designed to channel water and snow flow down these valleys in order to properly move the water off and onto the ground.
Because roof valleys see so much water flow, they need extra protection. After the underlayment is in place, metal flashing is installed on top of it to doubly secure the channel.
Step 6: Starter Shingle Installation
Water can get in between the seams (connections) of shingles. However, that’s OK because all shingles are designed to overlap between one another and the seams between them are staggered on purpose in order to properly channel this water away without it causing any damage.
That said, if all you did was have shingles installed across the roof as normal, then water would run in between the seams on the very first row of your roofing shingles and go right onto your underlayment, greatly increasing the odds of a leak happening.
That’s why starter strip shingles are installed at the bottom (to prevent water run in on the first row of shingles). These shingles are about half as wide as standard shingles. The reason they are only half the size is because if they were the full width of a normal shingle, the top half of the first row of shingles would have three layers of shingles instead of the two that the whole rest of the roof does, causing a very visible hump right at the edge of your roof and making it look terrible.
Step 7: Shingle Installation
We’re over half way through the whole roof installation process and finally, we start the most iconic part of getting a new roof: the shingle installation. Only after all the underlayments, drip edge, valley waterproofing and starter strip shingles are installed, can we properly install the main product.
This step is probably the simplest of all the steps in roofing installation. The bottom of the first row of shingles is lined up with the bottom edge of the starter strips, while making sure the seams themselves are staggered to avoid water running underneath the shingles.
As the shingles are lined up straight, each manufacturer has a specific nailing pattern designed to hold the strips in place properly, so each brand’s nailing pattern is slightly different, marked by nailing guidelines provided by the manufacturer (this is also a key point in holding up any roof warranty, if this isn’t properly done, most warranties are voided).
Step 8: Step & Dormer Flashing Installation
Flashing provides a nice watertight seal. Step and dormer flashing is installed right around the base of any siding that’s coming up on the roof (such as a second story in a house). The step flashing is woven in with the shingles so that water can’t get underneath them.
You can tell if flashing is installed because it will always be metal to create a hard seal.
Step 9: Installing Ridge Cap Shingles
Flashing provides a nice watertight seal. Step and dormer flashing is installed right around the base of any siding that’s coming up on the roof (such as a second story in a house). The step flashing is woven in with the shingles so that water can’t get underneath them.
You can tell flashing because it will always be metal to create a hard seal.
Step 10: Sealing and Roof Installation Completion
The final step in roof installation is cleaning up - the roofing contractors will sweep any debris leftover from construction off the roof and seal all of the exposed nails on flashing and vents. Asphalt based sealants are used, rather than silicone because silicone won’t hold up over time as a sealant on the roof.