How to Install Roof Shingles the RIGHT Way

Now that you’ve got your tools and materials ready, let’s walk through the installation process. Each step builds on the one before it, so take your time and follow the order carefully.

Step 1: Tear Off the Old Roof

The first step is removing the old shingles, nails, and underlayment. Work from the top (the ridge) down to the eaves. Once everything is cleared, sweep the deck so it’s clean and smooth.

As you go, check the wood decking underneath. If you notice soft, cracked, or rotted spots, replace them before moving on. A solid base is the foundation of a long-lasting roof.

Step 2: Install Drip Edge at the Eaves

Next, nail a drip edge (a thin strip of metal) along the bottom edges of the roof. Place nails about every 8–12 inches for security.

This small detail makes a big difference. The drip edge guides water into the gutters instead of letting it run behind them, protecting your fascia boards from rot and water damage.

Step 3: Roll Out Underlayment + Ice Barrier

With the deck prepped, roll out the synthetic underlayment starting at the bottom of the roof. Overlap each row by 4–6 inches so water can’t sneak underneath. Secure it with cap nails.

In Pittsburgh and Western PA, it’s smart to add an ice and water shield along the eaves, valleys, and roof penetrations. This extra layer prevents leaks caused by ice dams in the winter.

Step 4: Flash the “Leak Zones”

Install flashing in areas most likely to leak, such as valleys, chimneys, skylights, and where the roof meets walls. Each piece should overlap the one before it, like scales on a fish, so water runs downhill without slipping through.

Proper flashing is one of the most important steps. Done right, it directs water away from weak spots and adds years of protection to your roof.

Step 5: Snap Chalk Lines + Install Starter Strip

Use a chalk line to mark straight, level guidelines across your roof. This keeps your shingle rows aligned as you work upward.

Then, install starter shingles along the eaves (and rakes if needed). This is crucial in how to install roof shingles. Starter strips have adhesive that seals the bottom row in place, preventing wind from lifting the shingles.

Step 6: Lay the Field Shingles

Now it’s time for the main part of the roof installation: laying the shingles themselves.

• Begin at the bottom edge, just above the starter strip. Leave a small overhang of about 1/4 to 3/8 of an inch.
• Nail each shingle just below the seal strip—typically four nails per shingle, or six if your area is prone to high winds.
• Stagger the seams. Cut the first shingle of each new row (6″, 12″, 18″ pattern) so seams don’t line up.
• Keep checking your chalk lines as you go to make sure the rows stay straight.

Taking your time here pays off—neat, even rows not only look better but also last longer.

Step 7: Shingle the Valleys (Closed-Cut Method)

Valleys handle the most water flow on your roof, so they need extra care. With the closed-cut method:

• First, run shingles from one slope across the valley.
• Then, lay shingles from the other slope and trim them in a straight line about 2 inches from the valley’s center.
• Seal the cut edges lightly with roofing cement.

This creates a clean finish that channels water smoothly down the valley.

Step 8: Vent the Ridge + Add Ridge Caps

At the peak of your roof, cut a slot if you’re adding a ridge vent. Ventilation helps reduce attic heat and moisture, which protects your shingles and extends their lifespan.

Once the vent is in place, cover the ridge with ridge cap shingles. Overlap each piece to cover the nails of the one before it, giving the roof both strength and a polished finish.

Step 9: Final Inspection, Sealing, and Cleanup 

When all the shingles are in place, do a careful inspection. Look for:

• Exposed nails → cover them with roofing cement.
• Loose or lifted shingle edges → press them down, sealing if needed.
• Flashing → confirm there are no gaps or lifted sections.
• Gutters → clear out any debris or shingle granules.

Finally, clean up the yard. Sweep the ground with a magnet to pick up stray nails and bag up all debris. Take photos for your records and register your warranty if the shingle manufacturer requires it.

This last step is about peace of mind—catching little things now prevents big problems later.