Asphalt Shingle Roof Installation: Step-By-Step Guide & Cost

Thinking about stripping off those battered shingles and starting fresh? A typical 1,500-square-foot Colorado roof runs $5,000–$11,000 installed, and the job breaks down into nine stages—from inspection and tear-off to the final ridge-cap nail.

This guide walks motivated DIYers and homeowners through each step, explains required tools, safety rules, code checkpoints, and reveals real-world labor prices. By the end you’ll know exactly what a pro crew should do—and whether you’d rather tackle it yourself or call Semper Fi Restoration.

Step 1: Evaluate Your Roof and Set a Realistic Budget

Before a single shingle gets nailed, you need solid numbers—​square footage, slope limits, and dollars. A clear plan prevents mid-project sticker shock and ensures you’re not stacking fresh shingles on a tired deck.

Assess roof condition, pitch, and access

Start in the attic. Look for dark stains, sagging sheathing, or daylight peeking through—signs the deck may need partial replacement. Outside, measure the pitch with a 2-foot level and tape: rise ÷ run × 12. Asphalt shingles require a minimum 2:12 slope; steeper roofs shed water better but demand more safety gear. Note obstacles (skylights, tall landscaping, two-story drops) that can add labor hours or necessitate a boom lift.

Measure the roof and calculate material quantities

Sketch each roof plane, then use the quick formula:

(length × width) ÷ 100 = squares

Example: a 30 ft × 50 ft gable plane = 15 squares . Double it for both sides (30 squares), add 10 % for waste → 33 squares of shingles. Don’t forget underlayment, ice & water, and drip edge in similar quantities.

Break down expected costs

Colorado averages put labor at $250–$600 per square(People Also Ask). Materials vary by shingle grade:

Multiply the total per square by your 33 squares and you’ll see why the typical 1,500-sq-ft roof lands between $5,000 and $11,000.

Decide DIY or hire a professional crew

Budget isn’t just cash; it’s time and risk. A 20-square roof usually takes a four-person crew two long days, but a weekend warrior may spend four or five weekends. DIY saves labor but voids manufacturer warranties if installation guidelines are missed—​and your homeowners insurance may balk at self-inflicted leaks. Complex rooflines or hail-claim paperwork? That’s when a vetted, veteran-owned contractor like Semper Fi Restoration earns its keep with transparent bids and code-perfect workmanship.

Step 2: Gather Materials, Tools, and Safety Gear

With the budget locked, it’s shopping time. Lining up everything in advance keeps the project moving and prevents those dreaded extra trips to the hardware store when the roof is half-open to the sky.

Complete materials checklist

• Asphalt shingles (3-tab, architectural, or impact-resistant) — order by the square plus 10 % waste


• Synthetic or 15/30-lb felt underlayment


• Ice & water shield for eaves, valleys, and low-slope sections


• Metal drip edge (eave and rake)


• Starter strip shingles


• Step, valley, and counter-flashing


• Roofing nails (galvanized, 1 ¼–1 ½ in)


• Asphalt roof cement/sealant


• Ridge vent and matching cap shingles

Tool lineup for efficiency and safety

• Pneumatic roofing nailer with 120 psi compressor


• 16-oz roofing hammer (backup)


• Utility knives with hook blades + extra blades


• Chalk line & measuring tape


• Flat pry bar and shingle shovel for tear-off


• Ladder stabilizers, roof jacks, and planks


• Magnetic sweeper for post-job cleanup


• Heavy-duty tarps and trash chute or dumpster

Personal protective equipment & fall protection

• OSHA-rated full-body harness, rope grab, and anchors


• Non-slip roofing shoes or boots


• Hard hat, ANSI-rated eye protection, cut-resistant gloves


• Hearing protection when running a compressor or nailer

Code and permit essentials

Pull a roofing permit with your local building department before the first nail. Most Colorado jurisdictions—and the International Residential Code—require an approved underlayment on every asphalt shingle roof; skipping it risks leaks and voids the manufacturer’s warranty. Verify wind-zone nail patterns, ice-barrier width (eaves plus 24 in inside the warm wall), and ventilation minimums (1 sq ft per 300 sq ft attic floor) so your new roof cruises through final inspection.

Step 3: Tear-Off and Deck Preparation

With permits in hand and materials staged, it’s time to strip the roof down to bare wood. An orderly tear-off exposes hidden decay, lets you spot framing issues early, and gives the underlayment a smooth, nail-friendly surface.

Safe removal of old shingles and fasteners

Work from the peak down. Using a shingle shovel or flat spade, pry up a full course at a time and slide debris onto tarps or directly into a dumpster chute. Designate a “drop zone” away from windows and flower beds. Keep nails from becoming lawn landmines by pulling them as you go instead of relying solely on the post-job magnetic sweep. On two-story elevations, roof jacks and planks create a stable platform and cut fatigue—a big safety win.

Inspect and repair the roof deck

Once the last felt scrap is gone, walk every plane slowly. Look for:

• Dark rings or soft spots indicating rot


• Delaminated OSB edges


• Nail pops that could telegraph through new shingles

Replace any section that flexes more than ¹⁄₈ inch underfoot. Per IRC Table R803.2, ⁷⁄₁₆-inch OSB is the minimum for rafters spaced 24 inches on-center; go thicker if you’re adding solar or snow-retention gear.

Install drip edge at eaves first

Position metal so it overhangs the fascia ¼–¾ inch, then nail every 8–10 inches with 1¼-inch galvanized roofing nails. Lap adjoining pieces at least 2 inches and snip the corners for a clean fit. Leave rake edges for later; starting at the eaves directs any wind-driven rain back onto the flashing, not behind it.

Handle valley and edge cleanup

Remove all old metal and check valley boards for water staining. Scrape away asphalt build-up so new W-metal or ice membrane sits flush. A spotless substrate guarantees the next step—underlayment and flashing—bonds tight and stays leak-free.

Step 4: Install Underlayment, Ice & Water Shield, and Flashing

With the deck repaired and drip edge on the eaves, you’re ready for the first real waterproofing layer—the barrier that keeps wind-driven rain out even if a shingle blows off. Take your time here; 90 % of leaks on an asphalt shingle roof installation trace back to skipped or sloppy underlayment and flashing work.

Applying ice & water membrane

Start at the eaves where ice dams form. Peel-and-stick membrane must extend from the fascia up the roof until it reaches at least 24 in inside the heated wall—about two courses on a 4:12 slope. Overlap vertical seams 6 in and stagger them so they never line up with a shingle joint. Work in temps above 40 °F for full adhesion, pressing bubbles out with a roller. Add extra strips in valleys and around chimneys for bomb-proof protection.

Rolling out roofing underlayment

Synthetic rolls (≈ $18–$25 per square) weigh less and resist tearing better than 30-lb felt (≈ $12–$15 per square), which can wrinkle if it gets damp. Starting at the low edge, unroll parallel to the eave, keeping the printed guide lines straight. Horizontal laps: 2 in; end laps: 6 in. Fasten with plastic cap nails every 12 in along the edges and 24 in in the field—closer (≈ 6 in) in high-wind counties like Weld and Adams. Cover the rake drip edge after the first course, then tape the vertical seams if the roof may sit exposed for more than a week.

Flashing critical areas

Install W-metal or open valley flashing before field underlayment laps over its top edge. Against sidewalls, step flash every shingle course: 2 × 3 in exposure, nailed high so the next shingle covers the fastener. At chimneys, tuck counter-flashing 1 in into a reglet cut and seal with polyurethane, not just caulk on the surface. Pipe boots must match vent diameter; seat them on a bed of asphalt cement and finish with two nails on the upslope side only—seal those heads to finish the watertight envelope.

Step 5: Lay Starter Strip and First Course

The starter course is the foundation for every shingle above it. Get this row crooked or under-nailed and you’ll fight “fish mouths,” wind-lift, and warranty headaches for the life of the roof. Take an extra minute to orient the factory sealant correctly and to snap crisp chalk lines—your future self will thank you.

Position and secure starter shingles

Flip or use factory starter shingles so the adhesive strip sits at the eave edge, ready to bond with the first visible course. Let the starter overhang the drip edge ¾ in on the face and ⅜ in on the rakes; this channels runoff cleanly into the gutters. Butt joints must offset at least 4 in from the joints of the course above to stop water tracing. Nail 1½ in above the adhesive, one nail about 1 in from each end, the rest evenly spaced per manufacturer specs.

Establish straight lines

Snap a baseline chalk line the full width of the roof, exactly one shingle exposure (5 in for 3-tab; 6 in ± ⅛ for most architectural) above the starter. Additional lines every two or three courses keep the pattern square even when decking edges wander. Re-snap if dust or foot traffic smudges the guides.

Nail placement basics

Use 1¼ – 1½ in galvanized roofing nails driven flush—not sunk—so the head is tight against the shingle. Standard zones allow four nails per shingle; Colorado’s high-wind counties bump that to six, with the extra nails 1 in inboard of the ends. Nails must penetrate ¾ in into the sheathing or fully through, securing your asphalt shingle roof installation against the first Front Range gust.

Step 6: Install Field Shingles Efficiently

With the starter secure and guide lines snapped, the bulk of the asphalt shingle roof installation can finally fly. Consistency here pays off — straight courses shed water better, look sharper from the curb, and keep you inside the manufacturer’s wind-warranty window.

Choose the correct installation pattern

Architectural (laminated) shingles go on in a “step” pattern: each new course starts half a tab shorter than the one below so vertical seams stagger at least 6 in. Rack-style installation (running columns straight up the roof) is reserved for 3-tab products and only when the maker allows it. A quick ASCII helps visualize the step method:

 Course 3   |  ■ ■ ■ ■ ■ ■
Course 2     ■ ■ ■ ■ ■ ■
Course 1   ■ ■ ■ ■ ■ ■
Starter      ■ ■ ■ ■ ■ ■
 

Follow the printed nail line, keep nails 1 in above the cutout on 3-tabs or the adhesive strip on architectural, and never drive through the self-seal glue.

Work valleys, hips, and penetrations

For valleys, most Colorado crews prefer an open-metal style: run shingles across the valley, snap a chalk line 2 in from center, then trim and seal the cut edge. Closed-cut valleys also pass code if you back-caulk the cut edge 3/8 in bead. Hip areas finish after field shingles reach within 6 in of the peak; pre-bend shingles by warming them in the sun so they don’t crack. Around vents and skylights, slide step flashing under the upslope shingle and nail only on the top edge; dab asphalt cement over exposed heads.

Maintain ventilation and code compliance

Every few courses, pause to verify intake vents aren’t blocked and that factory slot-cut ridge vent length matches the code: at least 1 sq ft of net free area per 300 sq ft of attic floor, split 50/50 intake to exhaust. Adequate airflow prevents trapped heat that cooks shingles, voids warranties, and invites winter ice dams.

Step 7: Cap the Ridge and Complete Finishing Touches

The field shingles may do the heavy lifting, but the ridge is where wind pressure spikes and leaks love to start. Finishing strong with proper ridge ventilation, tight caps, and a little tube-of-goo finesse locks the whole system together and earns that final inspection sticker.

Install ridge caps and ridge vent

If you’re adding a continuous ridge vent, snap a center chalk line first, then cut a ¾-inch slot on each side of the ridge board—stop 6 in. short of hips and gable ends. Fasten the vent with 2 ½-in. roofing nails driven into the rafters below.

For caps, you’ve got two paths:

• Factory caps: faster, thicker, and usually come in prefab bundles.


• DIY caps: slice architectural shingles at the pre-cut lines or cut 3-tabs into thirds, then bend each piece over your knee to “set” the curve.
  
  Overlap each cap 5 in., running perpendicular to the prevailing wind so gusts don’t lift the seams. Nail 1 in. back from the leading edge; the next cap hides the fasteners.

Seal exposed fasteners and add accessories

Once the ridge is done, circle back with a tube of asphalt roof cement. Any nail head that isn’t covered—step flashing tops, final ridge cap nail, metal drip edge joints—gets a thumbnail-sized dab. On metal valleys, run a 3⁄8-in. bead under the shingle cut to keep wind-driven rain from backwashing.

Optional add-ons

Rooftop access is never cheaper than right now, so consider installing:

• Seamless gutters and downspouts


• Snow guards along lower courses to control slide-offs


• Heat cables in ice-dam zones


• Satellite dish mounts or solar conduit standoffs (flashed, not caulked)
  
  Tackling these extras while the crew and ladders are still on-site saves a future service call and makes the new asphalt shingle roof installation truly turnkey.

Step 8: Cleanup, Inspection, and Warranty Registration

A new roof isn’t finished until the ground is spotless, every shingle is double-checked, and the paperwork is filed. Skipping this wrap-up phase can scrap curb appeal, leave nails in tires, and even void manufacturer coverage.

Jobsite cleanup

• Roll a magnetic sweeper across lawns, planting beds, and the driveway—twice.


• Fold up tarps carefully so hidden nails don’t spill out.


• Load shingles and decking scraps into the dumpster, then schedule haul-off the same day to avoid HOA complaints.

Final inspection checklist

Grab a flashlight and garden hose:

1. Confirm nail lines—no overdrives or wide misses.


2. Tug on flashing to be sure it’s tight.


3. Verify ridge vent screws are seated.


4. Spray valleys and penetrations; check attic for drips.


5. Photograph everything for your records.

Register warranties and keep documentation

Most brands require online registration within 30–60 days. Upload the contractor invoice, permit sign-off, and at least six roof photos. Store digital copies plus a hard-copy “roof file” so future buyers—and your insurance company—can see the roof’s birth certificate at a glance.

Step 9: Maintain Your New Asphalt Shingle Roof

Even the best-installed roof needs a little TLC. A low-key maintenance routine protects your investment, preserves the manufacturer warranty, and helps you spot minor storm damage before it turns into drywall stains or an insurance claim headache.

Annual and seasonal inspections

Check the roof twice a year—​once after spring thaw and again after fall wind storms. A quick look with binoculars from the ground works for most homes; climb a ladder only if you’re comfortable and use a spotter. Scan for lifted tabs, missing granules, or shiny nail heads that signal a popped fastener.

Preventive maintenance tasks

• Clean gutters and downspouts so ice dams can’t back up under shingles.


• Trim branches to maintain a 6-foot clearance and prevent abrasion during Colorado’s gusty days.


• Sweep off pine needles and use a manufacturer-approved moss/algae wash; avoid bleach that can void warranties.


• After hail, feel shingle surfaces—exposed asphalt spots larger than a quarter merit a pro inspection.

Know when to call a professional

Curled edges, widespread granule loss, or interior ceiling spots mean it’s time for expert eyes. A certified crew can handle targeted repairs or confirm hail damage for an insurance claim. Catching issues early can extend an asphalt shingle roof’s service life by 5–10 years and keep your home snug through the next Front Range storm.

Roof Installation Simplified

In nine deliberate moves—budget, stock up, tear-off, waterproof, start, shingle, cap, inspect, maintain—you’ve gone from weather-beaten to weather-proof. Keep each phase in sequence and you’ll avoid the two classic rookie mistakes: rushing underlayment and skipping ventilation.

Remember the big three: plan ahead, work safely, and follow the shingle maker’s nailing and flashing diagrams to the letter. Those details lock in the wind warranty and add years to service life, which is doubly valuable along Colorado’s hail belt.

If that checklist still feels like a full-time job, hand it off to the veterans that live and breathe it. Semper Fi Restoration offers free, no-pressure roof assessments and itemized quotes—so you get the craftsmanship without the stress. Schedule yours today through Semper Fi Restoration.