How to Install Asphalt Shingles
A complete walkthrough for installing 3-tab or architectural asphalt shingles — from starter course to ridge cap.
Step-by-Step
- 1
Install drip edge at eaves
Nail drip edge along the eave before the ice and water shield. The drip edge goes under the ice and water shield at eaves — this is the one location where drip edge goes under the waterproofing layer. Space nails every 8–10 inches.
- 2
Install ice and water shield
Starting at the eave, apply ice and water shield over the drip edge. Extend at least 24 inches past the interior wall face (more in severe climates). Remove the release film as you roll — it is self-adhering to the deck. Apply to all valleys and around all penetrations.
- 3
Install underlayment
Roll out synthetic underlayment horizontally starting at the eave, overlapping each course by 4 inches. Fasten with cap nails at 12 inches OC. Lap upper courses over lower courses so water always sheds over the top. At the rake, lap over the edge by 1 inch.
- 4
Install drip edge at rakes
Install drip edge along the rake edges over the underlayment (opposite order from the eave). The rake drip edge always goes over the underlayment.
- 5
Install valley flashing
For open valleys, cut and install metal valley flashing over the ice and water shield. Nail only to the outer edges — center nails cause leaks. For closed valleys, weave shingles per the manufacturer's instructions.
- 6
Install starter course
The starter strip (or upside-down shingles with tabs removed) provides a solid shingle edge at the eave. The factory sealant strip on the starter aligns with the first course shingles above it, bonding them against wind uplift. Overhang the eave by 3/8–1/2 inch.
- 7
Snap layout lines
Snap horizontal chalk lines every 5 inches of exposure up the roof (for standard 3-tab shingles) or per the manufacturer's specified exposure. Consistent exposure lines keep the courses straight.
- 8
Install shingles
Begin the first course flush with the starter strip, offsetting joints by half a tab (or 6 inches for architectural shingles). Nail per the manufacturer's nail placement — typically 4 nails per 3-tab shingle, 1 inch above the sealant strip. Nails driven through the sealant zone blow off in wind.
- 9
Work up the roof
Maintain consistent exposure with each course. Stagger joints by at least 6 inches on every course. At walls, step-flash as you shingle — one piece of step flashing per shingle course, woven with the shingles.
- 10
Install ridge cap
Cut ridge cap shingles from standard shingles or use manufactured ridge cap. Start at the end opposite the prevailing wind direction, lap 5 inches, and nail 6 inches from each end. The last shingle at the peak gets nailed and sealed with roofing cement.
Pro Tips
- → Mix shingles from multiple bundles as you work to blend color variations from different production runs.
- → In cold weather (below 50°F), hand-seal every shingle tab with a dab of roofing cement — the factory sealant won't activate in cold.
- → Use roof jacks at all times on slopes above 6:12. Falls from roofs are among the most common construction fatalities.
Watch Out
- ! Never drive nails through the sealant strip — it prevents the self-sealing function and causes blow-offs.
- ! Improper flashing is the cause of most roof leaks — do not skip step flashing at walls or use only caulk.