How Asphalt Shingles Are Installed: The Sequence From Deck to Ridge

Published November 7, 2026

Asphalt shingles go on from the eaves up, over layers that each lap the one below: deck, eave drip edge, ice barrier where required, underlayment, rake drip edge, starter strip, field shingles, flashing and ridge cap. Each layer is covered by the next one soon after it goes down, so the only practical way to verify the work is during the job, through dated photos and the few details you can see from the ground.

This page covers what correct installation looks like layer by layer. Scheduling, permits and cleanup across the whole project are covered in the project-wide replacement timeline, and the decisions that come before and after the install, from choosing a material to hiring a roofer, are routed to their pages in the guide to every roof decision.

Why the Order of Layers Is the Waterproofing

A shingle roof is not watertight the way a membrane is. It works because every piece overlaps the piece below it, so water running downhill always lands on top of the next layer and never behind it.

Reverse one lap, so that a lower piece sits on top of an upper one, and water running down the roof is guided underneath instead of over. That is why sequence matters more than any single product: a premium shingle laid over a backward lap still leaks. Each step below is a lap that has to face the right way.

The Sequence From Deck to Ridge

On a tear-off, the crew strips the old roofing and works upward in this order. Manufacturer instructions and local code can change the details, as the next sections explain. On a recover, the old roofing stays in place, so the deck check in step 1 cannot happen; whether your roof qualifies for a recover is covered in overlay vs. tear-off.

Deck check. With the old roofing off, the crew inspects the sheathing and replaces soft, rotted or damaged sections. FEMA’s wind retrofit guide warns that deck panels on many existing roofs are under 15/32 inch thick, so the deck deserves a real look, not a glance. Deck materials and replacement are covered in roof decking.
Drip edge at the eaves. Metal edge flashing goes along the bottom edge of the roof. The Department of Energy (DOE) puts drip edge on the rakes as well as the eaves in its Building America guidance for asphalt shingle roofs; see drip edge rules for where code requires it.
Ice barrier where required. In climates where the local code requires it, a self-adhering membrane runs up from the eave. The City of Lincoln, Nebraska re-roof policy (December 2021, based on the 2018 International Residential Code) carries it to not less than 24 inches inside the exterior wall line. How that distance is measured is in ice and water shield requirements.
Underlayment over the field. Rows of underlayment are laid from the bottom up, each lapping the one below. On a low slope, from 2 in 12 up to 4 in 12, the DOE guidance calls for that underlayment to go on in a double layer. Product choices are compared in underlayment types.
Drip edge at the rakes. On the sloped gable edges, the drip edge goes on over the membrane underlayment, so water running along the edge stays on top of the metal.
Valley linings. Where two roof planes meet, the valley is lined before any shingles cross it; methods are compared in roof valleys.
Starter strip. A starter course along the eaves (and along the rakes, where the instructions call for it) puts sealant and a solid layer under the first exposed course. The same DOE guidance has the starter overhang the drip edge by 1/4 to 3/4 inch, and caps the starter and shingles at 1/4 inch past it on a roof built to the IBHS FORTIFIED standard; that edge detail is a different measurement from the depth of the eave overhang. Starter products are covered in starter strips and ridge caps.
Field shingles. Courses go up the roof, offset and exposed by the amounts printed in the manufacturer’s instructions. Nail count and placement are covered in correct roofing nail placement.
Flashing as the courses rise. Where the roof meets a sidewall, a kickout goes in first at the bottom of the intersection, and step flashing is woven in course by course above it so each piece laps onto the one below. Chimneys and pipes get their own flashing as the shingles reach them. The types are explained in roof flashing.
Hip and ridge caps. Cap shingles close the top, over a ridge vent if the ventilation design calls for one.

Checkpoints You Can Verify Without Climbing

You will not see most of this sequence from the yard, and you should not try to see it from the roof. A home inspection after the fact will not fill the gap either: under the InterNACHI Home Inspection Standards of Practice (revised October 2022), the inspector inspects from ground level or the eaves and is not required to walk on any roof surface or to confirm proper fastening or installation of any roof-covering material.

That leaves two tools: photos taken by the crew before each layer is covered, and the details that stay visible from the ground.

Ask for dated photos of:

The bare deck after tear-off, with any replaced sheets visible.
The ice barrier at the eaves, where required, before underlayment covers it.
The underlayment across the field, and the double layer on any section between 2:12 and 4:12.
Each valley lining before shingles cross it.
A course of field shingles with the nails showing, before the next course covers them.
Step flashing at each sidewall before siding or trim goes back on.
A close-up at the eave with a tape measure across the drip edge and shingle edge, showing the overhang.

Check from the ground, with binoculars if needed:

Drip edge metal visible along the eaves and, where your code requires it, the rakes.
A shingle edge that sits just past the metal, not hanging well beyond it; the photo with the tape settles the 1/4-inch question.
A kickout at the bottom end of every place a roof edge dies into a wall. Building America’s guide to step and kick-out flashing at roof-wall intersections uses it to steer water clear of the wall and into the gutter; kickout flashing explains what happens to the wall without one.

Where Instructions and Local Code Change the Details

The sequence above is the model. Four details shift by jurisdiction or product, and your contract should say which version applies.

Drip edge. The model text of the International Residential Code (IRC) calls for drip edge, but Minnesota’s residential code, as summarized by the City of Bloomington in June 2023, does not require it unless the shingle manufacturer does. Lincoln, Nebraska requires it on all eaves and gables. Ask your building department which rule applies.

Eave order. DOE guidance shows two eave sequences. Its guide to eaves sealed with self-adhering membrane in cold climates has the lower edge of the membrane covering the top edge of the drip edge, while another DOE roof-edge guide allows the eave drip edge to be installed over the fully adhered membrane. At the rakes, the DOE roof-edge guide puts the drip edge over the membrane. The manufacturer’s instructions for the exact membrane and shingle decide which eave order your crew uses.

Nails. The Asphalt Roofing Manufacturers Association’s guide to nail application of asphalt shingles calls for a minimum of four nails per full-size strip shingle for most shingles, placed below the sealant strip but above the area that will show, long enough to penetrate at least 3/4 inch into the deck. At least one manufacturer ties its higher wind warranty coverage to more nails per shingle plus its own starter products on some product lines; those conditions are explained in shingle wind ratings.

Cold weather. Shingle sealant strips need warmth to bond, and at least one manufacturer requires perimeter shingles to be hand-sealed with asphalt cement below a set temperature. The thresholds and methods are in roofing in cold weather.

When to Stop the Job Before the Next Layer

Some problems cost far less to fix while a layer is open than once it is covered. Ask the project lead to pause, in writing, if any of these show up:

Soft or thin decking. Spongy, delaminated or rotted sheathing found after tear-off gets replaced before underlayment goes on. Agree on the extent and the price in writing at that moment, using the deck terms in your contract.
A missing required layer. If your jurisdiction requires an ice barrier or drip edge and the photos show none, it has to go in before the shingles cover the eave.
Sealant where flashing belongs. A bead of caulk or roof cement at a wall, chimney or skylight is not flashing. Sealant can hide a gap for a while, but it does not form a lap, so water eventually finds its way behind it.
Shingles over a backward lap. Any photo where a lower piece sits on top of an upper one, at a valley, wall or pipe, is a leak path.

Some local policies also require a cricket behind wider chimneys; if yours does and the plan shows none, raise it before the chimney is flashed. The width trigger and construction are in chimney crickets.

Stay off the roof and out of the area below the eaves during tear-off and installation. Your checks happen in the photos and from the ground.

What to Put in Writing Before the First Bundle Goes Up

Before work starts, get three things in writing: the manufacturer’s installation instructions for the exact shingle, underlayment and starter products on the quote; the contractor’s agreement to send a dated photo of each layer before it is covered; and the correction process, meaning who can stop work, how a defect is documented, and how the fix is confirmed. Attach all three to the contract; the clauses that hold them are covered in what a roofing contract should include.

Then, on install days, review the photos the same evening and check the drip edge, edge overhang and kickouts from the ground before the crew leaves.

This guide is general information for U.S. homeowners, not legal, insurance, tax, or engineering advice. Codes, laws, and policy terms vary by location and change over time; confirm details with your local building department, your insurer, or a licensed professional.

Sources

Asphalt Shingle Roofs, U.S. Department of Energy Building America Solution Center
Re-Roof Policy, City of Lincoln, Nebraska Building and Safety
InterNACHI Home Inspection Standards of Practice, International Association of Certified Home Inspectors
Step and Kick-Out Flashing at Roof-Wall Intersections, U.S. Department of Energy Building America Solution Center
Roof Eaves Sealed with Self-Adhering Membrane in Cold Climates, U.S. Department of Energy Building America Solution Center
Nail Application of Asphalt Shingles, Asphalt Roofing Manufacturers Association