How to Install Roof Shingles:
The Ultimate Step-by-Step Guide

Step 1: Prepare Your Roof Surface

Proper preparation makes or breaks your installation.

Start by clearing the work area below. Move patio furniture, cars, grills, and anything else that could be damaged by falling debris. Put tarps down to catch nails and shingle pieces—your lawn and landscaping will thank you.

Remove all old shingles down to the bare roof deck. Use a roofing shovel to pry them up, working from the ridge down to the eaves. This is brutal physical labor in Long Island’s summer heat.

Pull out every single nail. Protruding nails will tear holes in your new shingles. Use a hammer to pound down stubborn ones or a pry bar to extract them completely.

Inspect your roof deck carefully. Look for soft spots, water damage, rot, or any sagging areas. Replace damaged plywood or OSB sheathing before going any further.

Check that all decking is securely fastened to the rafters. Add screws if you find any loose sections. Your new shingles need a solid, flat surface.

Sweep the entire deck clean. Remove all debris, old nails, and dirt. A clean surface ensures proper adhesion of your underlayment.

Now’s the time to address any structural issues. If you spot problems with rafters, trusses, or serious water damage, stop. These require professional assessment before you continue.

Step 2: Install Drip Edge at the Eaves

Drip edge seems like a small detail, but it’s critical.

This metal flashing runs along your eaves (the bottom edge) and rakes (the angled sides). It serves two purposes: directing water away from your fascia and into gutters, and creating a clean, finished edge.

• Start at one corner of your eaves. Line up the drip edge so it’s flush with the roof edge. Mark both ends with a pencil.
• Snap a chalk line between your marks for a straight reference line.
• Pull the drip edge down about half an inch from that chalk line. This creates the proper overhang.
• Nail it in place using 1¼-inch galvanized roofing nails spaced every 12 inches. Don’t overdrive the nails—flush is perfect.
• Overlap sections by about two inches where pieces meet. This prevents gaps where water could sneak through.

Here’s where installation order matters: At the eaves (bottom), drip edge goes on first, before underlayment. At the rakes (sides), it goes on after underlayment. This layering ensures water flows properly.

Step 3: Apply Ice and Water Barrier

Long Island winters demand serious ice dam protection.

Ice and water shield is a self-adhering membrane that seals against water infiltration. It’s especially critical for our climate where ice dams can force water back under shingles.

Start at the eaves. Roll out the ice and water barrier across the bottom of your roof, extending from the eave up at least 24 inches past the interior wall line. Local building codes may require more—check before you start.

Peel back the protective film as you go. Press the membrane firmly onto the deck, working out any bubbles or wrinkles. Use a J-roller if you have one for better adhesion.

Overlap the next course by at least four inches. The top course always overlaps the bottom one—remember, water flows downward.

Apply ice and water shield in all valleys where two roof planes meet. These are prime leak locations. Extend it at least 12 inches on both sides of the valley centerline.

Also protect areas around chimneys, skylights, dormers, and vent pipes. Any roof penetration needs this extra protection.

Work carefully—this stuff is sticky and difficult to reposition once it’s down. But don’t rush. Proper installation here prevents 90% of future leak problems.

Step 4: Install Roofing Underlayment

Underlayment creates your roof’s secondary weather barrier.

You have two main options: traditional felt (asphalt-saturated) or modern synthetic underlayment. Synthetic costs more but installs easier, lasts longer, and handles foot traffic better during installation.

Start at the bottom eave, right on top of your ice and water shield. Roll out the underlayment horizontally across the roof.

Overlap the ice and water barrier by at least four inches at the eaves. In valleys, overlap the valley membrane by at least six inches.

Secure it with cap nails or staples per manufacturer specifications. Typical spacing is every 12 inches along edges and 24 inches in the field.

Each successive row overlaps the one below it. Standard overlap is 2-4 inches on low-slope roofs, but check your local code. Steeper pitches may require different overlap amounts.

Keep the underlayment tight, straight, and smooth. Wrinkles and bubbles create weak points and look terrible when you’re done.

If you need two pieces to complete a course, overlap the vertical seams by at least six inches. Seal these joints with roofing cement for extra protection.

Step 5: Install Drip Edge at the Rakes

Remember how we skipped the rake drip edge earlier?

Now it goes on—over the underlayment this time. This installation order (under at eaves, over at rakes) is crucial for proper water management.

Measure and cut your rake drip edge pieces to length. Work up from the eave toward the ridge on each gabled end.

Nail through the underlayment into the roof deck every 12 inches. Make sure edges overlap by two inches at joints.

Step 6: Calculate and Mark Your Shingle Layout

Professional-looking results require precise layout.

Most architectural shingles have a 5 to 5⅝-inch exposure—meaning that’s how much of each shingle shows after the one above it overlaps.

Measure up from the eave edge and mark at 12 inches. This accounts for your starter course plus the first full shingle course.

From there, mark every 5 or 5⅝ inches (depending on your shingle specs) all the way up to the ridge. These marks show where each course sits.

Snap horizontal chalk lines at each mark. These lines keep your courses straight and your exposure consistent. Don’t skip this step—crooked courses look terrible and perform poorly.

Also snap vertical chalk lines every few feet to guide your stagger pattern. Most shingles need tabs offset by 6 inches from row to row, but check your manufacturer’s instructions.

Step 7: Install Starter Shingles

The starter course is your foundation—literally.

You have two options: buy pre-made starter strips or cut standard shingles. Pre-made starters save time and ensure proper adhesive placement. They’re worth the extra cost.

If you’re cutting your own, flip a standard three-tab shingle upside down and cut off the tabs. This leaves you with the top portion that has the adhesive strip.

Place your first starter shingle at the bottom corner, overhanging the drip edge by about ¼ to ½ inch. This overhang is critical—it directs water into the gutter instead of behind the fascia.

Nail it in place using four nails per shingle. Place nails 3-4 inches up from the bottom edge and about 1 inch from each end. The next full shingle course will cover these nails.

Continue across the entire eave with starter shingles, butting them tightly together. No gaps.

Run starter shingles up the rakes too if your manufacturer recommends it. Some do, some don’t—check the installation instructions.

Step 8: Install Your First Course of Field Shingles

Now comes the main event.

Place your first full shingle at the bottom left corner (or right if you’re left-handed—work in the direction that feels natural). Align it perfectly with your chalk lines and the starter course below.

Drive four nails per shingle for standard installations. High-wind areas (like much of coastal Long Island) require six nails.

Nail placement matters enormously. For most three-tab shingles, place nails about 1 inch from each end and 1 inch above the cutouts. For architectural shingles, follow the nail line marked by the manufacturer.

Drive nails straight in, not at an angle. Set them flush—not too deep (which punctures the shingle), and not too shallow (which creates a bump).

Each nail should penetrate through the shingle you’re installing AND the top portion of the shingle below it. This “double coverage” is what keeps your roof tight.

Continue across the entire first course, butting each shingle firmly against the next. No gaps between shingles.

Step 9: Create Your Stagger Pattern

Proper stagger prevents water infiltration and improves wind resistance.

For the second course, cut 6 inches off the first shingle before installing it. This offsets the seams from the first row.

Install this shortened shingle, lining its bottom edge with the top of the cutouts in the first course below. Nail it securely.

Continue across with full shingles for the rest of the second course.

For the third course, cut 12 inches off the first shingle. Fourth course uses a full shingle. Fifth course cuts 6 inches off again.

This creates a diagonal stagger pattern that prevents seam alignment. Aligned seams create leak paths—staggered seams don’t.

Follow this pattern (6″, 12″, full, repeat) all the way to the ridge. Stay consistent.

Some architectural shingles use different offset patterns—4 inches, 5 inches, or random offsets. Always follow your specific shingle manufacturer’s instructions. Their pattern is engineered for that particular shingle’s performance.

Step 10: Handle Roof Valleys Correctly

Valleys channel enormous amounts of water.

You have two main valley methods: open valley and closed valley.

Open valleys use metal flashing as a visible channel down the valley. The shingles stop short of the valley center, leaving the metal exposed.

To install an open valley, center your valley flashing in the valley. It should extend at least 12 inches on each side of the valley centerline.

Secure it with roofing nails along the edges only—never through the center where water flows. As shingles reach the valley, trim them at an angle following the valley line. Leave the metal exposed down the middle.

Seal the cut edges with roofing cement to prevent water from wicking under the shingles.

Closed valleys (also called woven or cut valleys) have shingles running across the valley. One side’s shingles extend across the valley, then the other side’s shingles are cut to fit and overlap.

This method requires precision cutting. Each shingle crossing the valley must be trimmed at the right angle and sealed properly.

For Long Island’s heavy rainfall and snow melt, we typically recommend open valleys with quality metal flashing. They handle high water volume better and last longer.

Step 11: Flash Around Chimneys and Penetrations

Every roof penetration is a potential leak point.

Step flashing protects where your roof meets vertical walls or chimneys. These are rectangular metal pieces that weave between shingle courses.

Each step flashing piece is about 10 inches long and bent at 90 degrees. Half sits on the roof, half runs up the wall or chimney.

As you install shingles alongside a chimney, install one piece of step flashing with each course. The next course of shingles covers each piece of step flashing.

Never nail through the flashing’s vertical leg—only through the part laying flat on the roof. The vertical portion needs to move independently.

Apply roofing cement between the flashing and the roof surface for a watertight seal.

Counter flashing goes on top of step flashing, typically embedded into mortar joints on brick chimneys. This creates a two-part system that accommodates building movement.

For plumbing vents, use rubber pipe boots. Slide the boot over the pipe, then cut the next shingle to fit around it. Apply roofing cement generously around the base.

Skylights require manufacturer-specific flashing kits. Don’t improvise—use the kit designed for that skylight model.

Step 12: Install Ridge Cap Shingles

The ridge is your roof’s crown—finish it right.

Never use standard field shingles on ridges. They don’t bend properly and won’t seal correctly. Ridge cap shingles are specifically designed for this application.

Some manufacturers sell pre-cut ridge cap pieces. Others require you to cut standard shingles into three pieces.

To cut your own, separate a three-tab shingle at the cutouts. Each tab becomes one ridge cap piece.

Start at one end of the ridge (downwind from prevailing winds if possible). Place your first ridge cap shingle so it straddles the peak, with equal coverage on both sides.

Nail it with two nails, one on each side, about 6 inches from the end and 1 inch down from the top edge.

Place the next ridge cap overlapping the first by about 5-6 inches. The overlap should hide the nails from the previous piece.

Continue across the entire ridge, maintaining consistent overlap and exposure.

For your last piece, you may need to trim it to length. Apply extra roofing cement under this final piece since you can’t overlap it.

Seal any exposed nail heads with small dabs of roofing cement. This prevents water infiltration.

Step 13: Final Inspection and Cleanup

Professional installations include thorough quality checks.

Walk the entire roof and inspect your work. Look for:

• Proper nail placement and driven flush

• Consistent shingle alignment and exposure

• All flashing properly sealed with no gaps

• Ridge caps secure and properly overlapped

• No lifted shingle corners or edges

Check that all cut edges are straight and sealed with cement where required.

Make sure no nails are exposed anywhere on the roof surface. Cover any you find with roofing cement.

Clean your gutters and downspouts. Installation debris will accumulate there.

Remove all nails, debris, and old materials from around your property. Use a magnetic sweeper on driveways and lawns—loose nails puncture tires and feet.

Inspect your property for any damage from falling materials. Better to catch it now than discover it weeks later.