For homeowners and building owners living through the work

A roof replacement is thirteen stages, and eleven are checkable from the ground.

Steep-slope · asphalt shingle · occupied house

The other two — the bare deck and the new flashings — are covered again on the day they are exposed, which is what makes them the only two stages nobody can check afterwards.

30-second answer

What actually happens during a roof replacement, and how would I know if it were going wrong?

A replacement runs in a forced order: permit, delivery, protection, tear-off, deck repair, underlayment, flashing, field shingles, ridge and ventilation, cleanup, final inspection. Every stage has a normal you can recognize and a failure you can name. Two of them, the bare deck and the new flashings, get covered the same day they are exposed, so photographs of those are the only record you will ever have.

Stop — immediate hazard

Stay off the roof, out of the attic, and out of the drop zone while a crew is working.

OSHA describes falls as among the most common causes of serious work-related injuries and deaths, and federal regulation requires employees in residential construction to be protected from falls at six feet and above. You have none of that protection, none of the training, and no reason to be up there. Every check on this page can be made from the ground, from a window, from a photograph, or from a document.

The attic is worse than the roof during tear-off. Debris, fasteners, and decades of dust come through the deck seams, the space is dark and often has no floor, and the ceiling below is not designed to carry a person. Ask the crew to photograph the underside of the deck instead of going up to look at it.

Older roofing products — shingles, felts, and mastics — may contain asbestos. The EPA is explicit that you generally cannot identify it by looking unless the material is labeled, that material in good condition should be left alone, and that sampling and removal are work for a trained and accredited professional. Raise it with your contractor before tear-off, not during it.

If you see the roof or a ceiling sag, hear cracking from the structure, smell smoke, or see anyone or anything contact the overhead electrical service drop: leave the building, keep everyone else out, and call 911 and your electric utility from outside. Do not go back in for belongings, and do not try to move a ladder or a person away from a line yourself.

Learning paths and saved lessons

At a glance

The short versionSection link

The value of knowing the sequence is not that you can supervise it. It is that you can tell which questions are still worth asking, and when it is too late to ask them.

Stages: 13, in a forced orderPhysics sets most of the sequence. Nothing can be flashed before the underlayment it laps onto, and nothing can be nailed to a deck that is still covered.
Checkable without climbing: 11 of 13The exceptions are the bare deck and the new flashings. Both are covered the same day they are exposed, so photographs are the only record.
Permits and inspections: Set by your jurisdictionOf the three jurisdictions checked for this page, the two that publish re-roof inspection procedures require different sequences — and Arvada, Colorado publishes that no ice barrier is required, where Seattle’s adopted code requires one at eaves with a history of ice.
The decision point: Deck condition, found at tear-offIt is the one price that cannot be known before the roof is opened, which is exactly why the unit price for it belongs in the signed contract.

The thirteen stages, what normal looks like at each, and what should prompt a question. Written for a steep-slope asphalt shingle replacement on an occupied single-family house.
Stage	What normal looks like	What should prompt a question
1. Contract and scheduling	A written scope naming the shingle product and color, the underlayment product, the ice-barrier extent, whether flashings are replaced or reused, the ventilation plan, a deck-replacement unit price and included quantity, who pulls the permit, and what triggers final payment. A start window rather than a start date, because weather moves crews.	“Deck replacement as needed.” No unit price, no included quantity, no photograph requirement. A firm start date promised in a week of rain. A deposit demanded before materials are ordered, with no stated delivery date.
2. Permit	The contractor pulls it in their own name, and the permit or its number is visible or available before tear-off. You can look the permit up on your building department’s portal. The contractor knows which inspections your jurisdiction requires and when they have to be called.	“You do not need a permit for a re-roof.” That may be true where you live and it may not; it is a question for your building department, not for the person being paid to skip it. Also a flag: a permit pulled in the owner’s name, which moves the code responsibility to you.
3. Material delivery and staging	Bundles delivered shortly before the work, stacked flat, and either kept on the ground or spread across the roof rather than piled in one place. Accessories on site too: starter, ridge, ice barrier, drip edge, pipe boots, step flashing, nails of the specified type.	Bundles bent over the ridge, or a single stack concentrated on one span. Materials that do not match the contract, especially a substituted underlayment or a missing ice barrier. Nothing on site but shingles, on a job that was scoped to include new flashing.
4. Property protection	Tarps or plywood over plantings, walls, and the ground below every eave being torn off. The dumpster or dump trailer placed on plywood if it is on the driveway. Vehicles moved out, gutters protected or scheduled for replacement, and a stated plan for the air-conditioning condenser and any deck furniture.	Tear-off starting before anything is covered. A dumpster set directly on a driveway you care about. No conversation about the attic, where the dust and debris will land on anything stored under the deck.
5. Tear-off	All existing layers removed down to the bare deck, including the old underlayment, on the area that will be reroofed that day. The crew works in sections sized to what they can dry in before the end of the day. Debris moves off the roof continuously rather than piling on it.	New shingles going over the old ones when the contract said tear-off. More of the roof opened than the crew can cover before dark or before weather. The old underlayment left in place under new underlayment, which hides the deck it was supposed to expose.
6. Deck inspection and the deck decision	The crew walks the bare deck, marks soft, delaminated, cracked, or badly holed sheets, and stops to show you or photograph them before covering anything. Deck fasteners are checked and re-nailed where they have backed out. A written change order, with a count and the contract unit price, comes before the replacement is installed.	A verbal number given from the roof with the deck already half covered. A count that grows after the fact. Replacement sheets thinner than the existing deck, or spanning the same rafter bay as the sheet they replaced without landing on framing at both ends.
7. Control layers: ice barrier, underlayment, drip edge	Drip edge at the eaves goes on first and the underlayment laps over it; at the rakes the underlayment goes first and the drip edge covers it. Ice barrier, where it is required, runs from the eave edge to a line measured inside the exterior wall, not to the fascia. Underlayment is fastened as the manufacturer specifies, not tacked with a handful of staples.	Underlayment tucked under the eave drip edge, which sends water behind the fascia. No drip edge at the rakes. Ice barrier stopped at the wall line you can see from outside rather than measured inside it. Loose, wrinkled, or lifting underlayment left overnight.
8. Flashing and detail work	Step flashing at every wall intersection replaced piece by piece, one per shingle course, woven into the courses. New pipe boots. New or properly re-set counterflashing at the chimney. Valley lining installed before the shingles that cover it. Kickout flashing where a roof edge dies into a wall above a gutter.	A continuous strip of bent metal and a bead of sealant in place of individual step flashings. Old step flashing reused because “it looked fine.” A pipe boot with the original cracked rubber collar left on. Sealant used as the waterproofing rather than as a backup to it.
9. Field installation	Starter course at the eaves and, on many products, at the rakes. Courses run horizontally across the roof. Nails driven flush, in the marked nailing area, penetrating the sheathing by the depth the manufacturer specifies. In cold weather, the perimeter hand-sealed.	Nails driven through the shingle face (over-driven) or standing proud (under-driven). Nails placed above the marked area, which leaves the course below held by nothing. Shingles “racked” straight up the roof rather than laid across it. Staples instead of nails where the instructions require nails.
10. Ridge, hips, and ventilation	The ridge slot cut to the width the vent product specifies, then covered with the specified vent and ridge cap. One kind of exhaust, not several. Intake at the eaves confirmed to be open, with insulation held back off the sheathing at the vent.	A ridge vent added while the existing box or powered vents are left in place, so the ridge pulls its air from them instead of from the soffits. Soffit vents painted, blocked by insulation, or never cut in behind the perforated panel. A ventilation change made with no reference to how the attic is insulated.
11. Cleanup and magnet sweep	Gutters cleared of granules and nails. A rolling magnet run over the driveway, the walks, the lawn, and the beds, more than once, and at least once in a different direction. Debris removed from the site the same day the roof is finished.	One pass with the magnet, in one direction, on the driveway only. Debris left in the beds because it “will settle in.” A dumpster left on site for days after completion with no removal date.
12. Final inspection	The contractor calls for whatever inspections the permit requires, and the permit is closed out. You receive the inspection result, not just a verbal “it passed.” Anything the inspector called out is corrected and re-inspected.	A permit left open after the crew is gone. This is the version of the problem that surfaces years later, at resale, when the open permit shows up in a title or municipal search.
13. Documentation and warranty registration	A closeout package: final invoice, the closed permit, the deck change order with photographs, the exact shingle product, color and lot where available, the accessories actually used, the manufacturer warranty registration confirmation, and the workmanship warranty in writing with its start date.	A warranty described in the sales conversation but never delivered as a document. A registration you were told was submitted but cannot see. Leftover bundles hauled away, with no record of the product for the first repair.

Read this table one item at a time

1. Contract and scheduling

What normal looks like: A written scope naming the shingle product and color, the underlayment product, the ice-barrier extent, whether flashings are replaced or reused, the ventilation plan, a deck-replacement unit price and included quantity, who pulls the permit, and what triggers final payment. A start window rather than a start date, because weather moves crews.
What should prompt a question: “Deck replacement as needed.” No unit price, no included quantity, no photograph requirement. A firm start date promised in a week of rain. A deposit demanded before materials are ordered, with no stated delivery date.

2. Permit

What normal looks like: The contractor pulls it in their own name, and the permit or its number is visible or available before tear-off. You can look the permit up on your building department’s portal. The contractor knows which inspections your jurisdiction requires and when they have to be called.
What should prompt a question: “You do not need a permit for a re-roof.” That may be true where you live and it may not; it is a question for your building department, not for the person being paid to skip it. Also a flag: a permit pulled in the owner’s name, which moves the code responsibility to you.

3. Material delivery and staging

What normal looks like: Bundles delivered shortly before the work, stacked flat, and either kept on the ground or spread across the roof rather than piled in one place. Accessories on site too: starter, ridge, ice barrier, drip edge, pipe boots, step flashing, nails of the specified type.
What should prompt a question: Bundles bent over the ridge, or a single stack concentrated on one span. Materials that do not match the contract, especially a substituted underlayment or a missing ice barrier. Nothing on site but shingles, on a job that was scoped to include new flashing.

4. Property protection

What normal looks like: Tarps or plywood over plantings, walls, and the ground below every eave being torn off. The dumpster or dump trailer placed on plywood if it is on the driveway. Vehicles moved out, gutters protected or scheduled for replacement, and a stated plan for the air-conditioning condenser and any deck furniture.
What should prompt a question: Tear-off starting before anything is covered. A dumpster set directly on a driveway you care about. No conversation about the attic, where the dust and debris will land on anything stored under the deck.

5. Tear-off

What normal looks like: All existing layers removed down to the bare deck, including the old underlayment, on the area that will be reroofed that day. The crew works in sections sized to what they can dry in before the end of the day. Debris moves off the roof continuously rather than piling on it.
What should prompt a question: New shingles going over the old ones when the contract said tear-off. More of the roof opened than the crew can cover before dark or before weather. The old underlayment left in place under new underlayment, which hides the deck it was supposed to expose.

6. Deck inspection and the deck decision

What normal looks like: The crew walks the bare deck, marks soft, delaminated, cracked, or badly holed sheets, and stops to show you or photograph them before covering anything. Deck fasteners are checked and re-nailed where they have backed out. A written change order, with a count and the contract unit price, comes before the replacement is installed.
What should prompt a question: A verbal number given from the roof with the deck already half covered. A count that grows after the fact. Replacement sheets thinner than the existing deck, or spanning the same rafter bay as the sheet they replaced without landing on framing at both ends.

7. Control layers: ice barrier, underlayment, drip edge

What normal looks like: Drip edge at the eaves goes on first and the underlayment laps over it; at the rakes the underlayment goes first and the drip edge covers it. Ice barrier, where it is required, runs from the eave edge to a line measured inside the exterior wall, not to the fascia. Underlayment is fastened as the manufacturer specifies, not tacked with a handful of staples.
What should prompt a question: Underlayment tucked under the eave drip edge, which sends water behind the fascia. No drip edge at the rakes. Ice barrier stopped at the wall line you can see from outside rather than measured inside it. Loose, wrinkled, or lifting underlayment left overnight.

8. Flashing and detail work

What normal looks like: Step flashing at every wall intersection replaced piece by piece, one per shingle course, woven into the courses. New pipe boots. New or properly re-set counterflashing at the chimney. Valley lining installed before the shingles that cover it. Kickout flashing where a roof edge dies into a wall above a gutter.
What should prompt a question: A continuous strip of bent metal and a bead of sealant in place of individual step flashings. Old step flashing reused because “it looked fine.” A pipe boot with the original cracked rubber collar left on. Sealant used as the waterproofing rather than as a backup to it.

9. Field installation

What normal looks like: Starter course at the eaves and, on many products, at the rakes. Courses run horizontally across the roof. Nails driven flush, in the marked nailing area, penetrating the sheathing by the depth the manufacturer specifies. In cold weather, the perimeter hand-sealed.
What should prompt a question: Nails driven through the shingle face (over-driven) or standing proud (under-driven). Nails placed above the marked area, which leaves the course below held by nothing. Shingles “racked” straight up the roof rather than laid across it. Staples instead of nails where the instructions require nails.

10. Ridge, hips, and ventilation

What normal looks like: The ridge slot cut to the width the vent product specifies, then covered with the specified vent and ridge cap. One kind of exhaust, not several. Intake at the eaves confirmed to be open, with insulation held back off the sheathing at the vent.
What should prompt a question: A ridge vent added while the existing box or powered vents are left in place, so the ridge pulls its air from them instead of from the soffits. Soffit vents painted, blocked by insulation, or never cut in behind the perforated panel. A ventilation change made with no reference to how the attic is insulated.

11. Cleanup and magnet sweep

What normal looks like: Gutters cleared of granules and nails. A rolling magnet run over the driveway, the walks, the lawn, and the beds, more than once, and at least once in a different direction. Debris removed from the site the same day the roof is finished.
What should prompt a question: One pass with the magnet, in one direction, on the driveway only. Debris left in the beds because it “will settle in.” A dumpster left on site for days after completion with no removal date.

12. Final inspection

What normal looks like: The contractor calls for whatever inspections the permit requires, and the permit is closed out. You receive the inspection result, not just a verbal “it passed.” Anything the inspector called out is corrected and re-inspected.
What should prompt a question: A permit left open after the crew is gone. This is the version of the problem that surfaces years later, at resale, when the open permit shows up in a title or municipal search.

13. Documentation and warranty registration

What normal looks like: A closeout package: final invoice, the closed permit, the deck change order with photographs, the exact shingle product, color and lot where available, the accessories actually used, the manufacturer warranty registration confirmation, and the workmanship warranty in writing with its start date.
What should prompt a question: A warranty described in the sales conversation but never delivered as a document. A registration you were told was submitted but cannot see. Leftover bundles hauled away, with no record of the product for the first repair.

Written for a steep-slope asphalt shingle replacement. The permit, deck, cleanup, inspection, and documentation stages carry over to tile, slate, metal, and residential low-slope work; stages 7 through 10 do not. What counts as normal in your jurisdiction is set by the code edition it has adopted and by its own amendments, so treat the middle column as the shape of the answer, not the answer.

Tradeoffs

When watching the sequence helps, and when it does notSection link

This page argues that a homeowner should learn the sequence and require photographs at two points. That advice is not right for everyone, and it is actively wrong in a few situations.

Best when

You are the person signing the contract and approving change orders, and you can be reached during working hours.
It is a full tear-off on a steep-slope asphalt roof, where the stages are visible from outside and the failure modes are well documented.
The contract is still unsigned, so the deck unit price, the flashing scope, and the photograph requirement can still be written into it.
The building is occupied, which makes the practical arrangements — parking, pets, attic contents, noise windows — worth planning a week ahead.

Think twice if

Knowing the sequence turns into standing in the drop zone to check it. The single most dangerous thing on this page would be a homeowner walking the perimeter during tear-off to look at flashings.
You are not the decision-maker. On an insurance-scope job, a landlord’s property, or an HOA-controlled building, the scope you are watching may not be the scope anyone will agree to change.
The covering is tile, slate, metal, or a low-slope membrane. The frame still holds, but the middle stages, the failure modes, and the crews are different enough that this page will mislead you on the details.
The relationship is already adversarial. A list of things to challenge, deployed mid-project against a crew you do not trust, produces a stopped job and a partially open roof — which is worse than either outcome you were choosing between.

What changes the answer

Your jurisdiction’s adopted code edition and amendments, which decide whether there is a permit, how many inspections there are, and whether an ice barrier is required at all.
Whether the roof is being torn off or recovered. A recover has no bare-deck stage, which removes the single most informative moment in the project.
The manufacturer’s instructions for the exact product being installed: fastener count and placement, starter requirements, ventilation conditions, and cold-weather handling are all product-specific.
Season. A roof installed in cold weather may not seal until spring, which changes what a wind event in the meantime means and what the crew should have hand-sealed.
Whether an enhanced manufacturer warranty is part of the deal. Where one is offered, it is conditioned on a specified set of accessories and often on a registered installer, and that changes what may be substituted at delivery.
Occupancy and access: a rowhouse with no driveway, a house under mature trees, or a building with overhead service lines changes staging, disposal, and the safe working area before anything else.

Why the order is forced

The sequence is water running downhill, in reverseSection link

A roof sheds water by overlapping, from the bottom up, so that every joint drains onto the piece below it rather than behind it. That single rule dictates the order of the whole project.

The lap order reverses between the two edges of the same roof. At the eave the metal drip edge is fastened to the deck first and the underlayment is laid on top of it, so water running down the underlayment is carried out over the metal and into the gutter. At the rake the order flips: the underlayment goes down first and the drip edge is fastened over it, holding the edge down against wind lift. Getting this backwards at the eave sends water behind the fascia, where it is invisible until the board rots.Original diagram, Understanding Roofing. Lap order per 2021 Seattle Residential Code R905.2.8.5, an adopted local code — confirm the requirement with your own jurisdiction.

Almost every question about “why are they doing it in that order” has the same answer. Water leaves a sloped roof by gravity, and the assembly is built so that the upper piece always laps over the lower one. You cannot install a piece until the piece it laps onto exists, and you cannot install the piece it laps onto until the deck under both of them is exposed and sound.

That is why tear-off comes before the deck decision, why the deck decision comes before the underlayment, why the underlayment comes before the flashing at every wall and penetration, and why the ridge is last. It is also why an incomplete day is not a problem in itself: the crew can stop anywhere, as long as they stop at a complete lap.

The layers, named, so the rest of this page makes sense

Deck (also sheathing): the structural skin nailed across the rafters or trusses. Usually plywood or OSB panels in modern construction, or spaced or tongue-and-groove boards in older houses. Everything above it is fastened into it, so its condition sets what the roof can hold.

Underlayment: the sheet material rolled over the whole deck before the covering goes on. It is the secondary water barrier, and it is what keeps the building dry between tear-off and shingles. Asphalt-saturated felt and synthetic sheets are both in normal use.

Ice barrier: a self-adhering membrane, or two cemented layers of underlayment, applied at the eaves where water backing up behind ice would otherwise get under the covering. Where it is required, the adopted text measures its extent inland from the eave to a point a stated distance inside the exterior wall line, which is further up the roof than most people assume — not less than 24 inches, in the 2021 Seattle Residential Code. Whether an ice barrier is required at all, and how far it runs, is set by the code your own jurisdiction has adopted.

Drip edge: the L-shaped metal at the eave and rake edges. It carries water clear of the fascia, gives the shingle edges something to sit on, and holds the underlayment down at the rake.

Flashing: the metal at every place the roof plane is interrupted — walls, chimneys, skylights, pipes, valleys. Step flashing is the piece-per-course kind used where a roof runs up against a wall. Counterflashing is the piece let into or fastened onto the wall above it, covering the top of the step flashing. Kickout flashing is the piece at the bottom of that run that throws water out into the gutter instead of down inside the wall.

Starter course: a purpose-made strip at the eave (and often the rake) with an adhesive line positioned to grip the first course of shingles. It is not the same thing as an upside-down shingle, and on many products the wind warranty depends on it.

Square: 100 square feet of roof surface. It is the unit crews and quotes count in, and it is roof surface, not floor footprint.

Two moments that cannot be checked afterwards

Every stage on this page leaves evidence except two. Once the underlayment is down, the deck is gone from view for the life of the roof. Once the shingles cover the step flashing, the only thing you can see is the bottom edge of the counterflashing. Both of those get covered within hours of being exposed.

This is why the single highest-value thing a homeowner can ask for is not supervision. It is a photograph: the bare deck, and the flashings before the courses go over them. It costs the crew about two minutes, it makes the deck change order verifiable instead of conversational, and it is the only documentation that will exist if a leak appears at that wall in four years.

The money conversation

The deck discovery, and the allowance that should already be in the contractSection link

Deck condition is the only major cost on a roof replacement that genuinely cannot be known before the work starts. That is not a reason to leave it open. It is the reason to price it in advance.

Until the old covering is off, nobody knows what the sheathing looks like. A crew can infer a lot from the outside — a sagging plane, a history of leaks at a valley, an interior stain — but the deck itself is behind everything. So at some point on tear-off day, a foreman is standing on a bare deck with a number in his head, and you are on the phone.

Whether that conversation is a two-minute confirmation or a dispute was decided weeks earlier, by a single clause. Here is the same discovery run through four common versions of that clause.

The same finding — 14 soft sheets of sheathing on a 2,800 sq ft roof — under four contract clauses. No dollar figure below is a market price; the unit price is whichever number your own contract names.
What the contract says	What happens when 14 sheets are found	What you can actually dispute
“Deck replacement as needed”	A number arrives after the fact, set by whoever is on the roof. You have no agreed unit price, no agreed count, and no agreed evidence standard.	Almost nothing. You can dispute the count if photographs exist, and photographs were not required.
“Includes up to 3 sheets; additional at the contract unit price, photographed, approved in writing before installation”	11 sheets are billed at the price you already agreed to, against photographs, before they go on.	The count, against the photographs. The price is already settled, which is the entire point of the clause.
“Deck replacement not included”	Every sheet is a change order priced during the job. Honest, and much better than silence — but all the leverage sits on the other side of the conversation.	The price and the count, both, mid-project, with the roof open. This is the worst moment to negotiate either one.
“Deck allowance of a stated dollar amount”	Work is drawn against a pot of money rather than a count of sheets. Fine if the unit price is also stated; otherwise the allowance can be consumed by an unstated rate.	How the allowance was spent — but only if the contract also names the unit price it is being spent at.

Read this table one item at a time

“Deck replacement as needed”

What happens when 14 sheets are found: A number arrives after the fact, set by whoever is on the roof. You have no agreed unit price, no agreed count, and no agreed evidence standard.
What you can actually dispute: Almost nothing. You can dispute the count if photographs exist, and photographs were not required.

“Includes up to 3 sheets; additional at the contract unit price, photographed, approved in writing before installation”

What happens when 14 sheets are found: 11 sheets are billed at the price you already agreed to, against photographs, before they go on.
What you can actually dispute: The count, against the photographs. The price is already settled, which is the entire point of the clause.

“Deck replacement not included”

What happens when 14 sheets are found: Every sheet is a change order priced during the job. Honest, and much better than silence — but all the leverage sits on the other side of the conversation.
What you can actually dispute: The price and the count, both, mid-project, with the roof open. This is the worst moment to negotiate either one.

“Deck allowance of a stated dollar amount”

What happens when 14 sheets are found: Work is drawn against a pot of money rather than a count of sheets. Fine if the unit price is also stated; otherwise the allowance can be consumed by an unstated rate.
What you can actually dispute: How the allowance was spent — but only if the contract also names the unit price it is being spent at.

An allowance is a budget. A unit price is a rate. They are not substitutes, and a contract that names only one of them has left the other to be decided on the day.

The arithmetic, worked

Take a roof with 2,800 sq ft of roof surface — that is surface area, not the footprint of the house, and it is 28 squares at 100 sq ft per square. Sheathing panels are 4 ft × 8 ft, so each covers 32 sq ft:

Sheets to cover the whole deck: 2,800 ÷ 32 = 87.5, so 88 sheets.
Sheets found soft at the north eave: 14. That is 14 ÷ 88 = 15.9% of the deck. There is no percentage at which a full re-deck becomes required; the question is whether each remaining sheet is sound.
Sheets included in the contract price: 3. Billable sheets: 14 − 3 = 11.

Now run the same 11 sheets at two different unit prices. These two numbers are chosen to show a spread; neither is this site’s estimate of what deck replacement costs anywhere:

At $80 per sheet installed: 11 × $80 = $880.
At $180 per sheet installed: 11 × $180 = $1,980.
Difference on an identical finding: $1,100, or 2.25× — decided entirely by a number that either was or was not written down before the first shingle came off.

The lesson is not that one of those unit prices is right. Deck replacement pricing varies with market, panel type, thickness, access, and how much of the work is patching versus sheeting a plane; this site does not publish a figure for it, because it has no dataset it could defend. The lesson is that the clause is worth more than the number, and the clause is free to negotiate before signing.

Three details that decide the count

Partial sheets. A soft patch two feet across usually means a whole panel is cut out and replaced, because a panel has to land on framing at its edges. Ask whether partial sheets are billed as whole sheets. Either answer is defensible; what is not defensible is finding out which one applies after the count has been made.

Thickness and type. A replacement panel that is thinner than the deck around it leaves a step under the shingles and a different fastener depth. One manufacturer’s current instructions set minimums of 3/8 inch plywood, 7/16 inch OSB, or 6-inch boards, and require the deck to comply with local code. Match the existing thickness, and say so in the contract.

Spaced sheathing. Older houses often have boards with gaps rather than continuous panels. The 2021 Seattle Residential Code requires asphalt shingles to be fastened to solidly sheathed decks (R905.2.1), and Arvada, Colorado publishes a specific threshold: spaced sheathing with spaces not greater than 1/2 inch can be reused where it is still structurally sound, and gaps larger than that across most of the roof mean replacing it with solid sheathing. Your jurisdiction may publish a different number, or none. If your house has board sheathing, this is not a deck-allowance question at all — it is a scope question, and it needs answering before you have a price.

This page publishes no cost range for roofing work, and the two unit prices above are illustrative arithmetic rather than market data. The only price that binds anyone is the one written in a signed scope of work for this building.

Weather

Stoppages, and what a properly dried-in roof looks like overnightSection link

Rain in the middle of a roof replacement is normal. An open deck in the rain is not. The difference is a decision the crew made hours earlier about how much roof to take off.

Dried in means the roof is watertight without its finish covering: the deck is fully covered with underlayment, the sheets are lapped in the shedding direction and fastened as the manufacturer requires, penetrations are sealed or temporarily flashed, and the edges are terminated. A dried-in roof can sit through a rain event. A roof that has been torn off and covered with a tarp cannot, reliably.

This is the reason competent crews tear off in sections. The size of the section is set by what they can dry in before dark or before weather, not by how much of the roof they would like to have open. A crew that strips an entire large roof at nine in the morning has made a bet, and you are the one holding the ticket.

What to look for at the end of an incomplete day

No bare deck anywhere. Every square foot that was opened is under underlayment or under shingles.
The underlayment laps run the right way, upper sheet over lower, so water crossing a seam runs onto the sheet below rather than into it.
The ridge is either shingled, capped, or wrapped — not left as an open slot with the ridge board exposed to the sky.
The underlayment is fastened, not tacked. Loose or lifting sheets in an overnight wind are how a dried-in roof stops being dried in.
Nothing is left on the roof that can move: no loose bundles at the eave, no tools, no debris pile waiting for the morning.
If a tarp is being used over anything, it is fastened at the top edge above the exposed area and lapped over the covering below it, not weighted at four corners on top of the hole.

Cold and the sealing problem

Asphalt shingles do not bond when they are installed. They bond later, when a factory-applied adhesive strip is activated by sun and surface temperature. One manufacturer’s current technical bulletin says directly that shingles installed in cold weather may not seal until warmer temperatures arrive, that extra care is needed when air and surface temperatures are at or below 40°F, and that every shingle on the perimeter of the roof should be hand-sealed with an ASTM D4586-compliant asphalt roof cement — four one-inch dabs on laminate shingles, two under each tab on three-tab — to protect against uplift while the strip is inactive.

Two practical consequences. First, a roof installed in December that has not sealed is not a defective roof — but it is a more vulnerable one, and IBHS notes that wind can lift unsealed shingles and water can seep underneath them. Second, if a winter installation loses shingles in a spring wind event, the argument will be about whether the perimeter was hand-sealed, and the time to ask that question is before the crew leaves, not after.

Manufacturer instructions also direct the installer to prevent the wood deck from getting wet before, during, and after installation. That is why a crew that stops work in light rain is behaving correctly and a crew that shingles through it is not, whatever the schedule says.

The practical week

Noise, debris, driveways, pets, and the things in your atticSection link

None of this affects how long the roof lasts. All of it affects whether the week is tolerable, and every item is easier to arrange three days early than on the morning.

A tear-off is loud in a way that is hard to convey in advance. The noise is not the crew; it is the impact of scrapers and nail guns transmitted through the structure, which is why it is loudest inside the house, and why it does not help to close a window. Pneumatic nailers run in bursts from early morning until the light goes. If you work from home, plan to work elsewhere. If anyone in the house sleeps during the day, that is a conversation to have before the start date, not on it.

Pets are the item people most often underestimate. Dogs and cats react badly to overhead impact noise and to strangers moving around the perimeter, and gates get left open by crews carrying material. Board them, or keep them in one interior room with the door closed and a sign on it. Do not leave animals in a yard the crew is working over.

Before the truck arrives

Driveway. Decide where the dumpster or dump trailer goes, and ask for plywood under the wheels and jacks. Move every vehicle you will need during the week out of the perimeter — not just out of the drop zone, but out of anywhere a bundle-loading truck wants.
Attic contents. Tear-off drops debris, fasteners, and decades of dust through the deck seams. Anything stored under the roof gets it. Cover boxes with plastic sheeting or move them out before the work rather than cleaning them after — and let the crew do any covering that requires being in the attic.
Interior. The whole structure vibrates. Take pictures off walls in rooms directly under the roof, and move anything on open shelving that would not survive being walked past hard.
Landscaping. Point out what matters and get agreement on how it will be protected. Plywood leaning against a shrub is not the same as a tarp over it, and the beds directly under the eaves take the worst of both the debris and the cleanup.
Equipment. Air-conditioning condensers, satellite dishes, solar equipment, and gutter guards all need a stated plan. Solar is the one that changes the schedule: panels usually have to be removed and reinstalled by someone qualified to do it, and that is a separate trade and a separate cost.
Access and services. Confirm where the crew may park, whether they may use an exterior outlet or hose bib, and whether anyone needs to be home. Usually nobody does — but somebody has to be reachable by phone for stage six.

Nails, for the next two years

Fasteners end up in the driveway, the lawn, the beds, the gutters, and the street. A rolling magnet gets most of the steel ones on hard surfaces. It does not lift aluminum or copper, and it does not find nails trodden into turf or mulch. Ask for multiple passes in more than one direction, including over planting beds and lawn, and make the final cleanup part of what triggers final payment. Then walk the perimeter yourself before you release it — from the ground, in daylight, which is the only inspection on this entire page that you should personally perform.

Considerations

What changes this on a real buildingSection link

The stages above are the same everywhere. What each stage is required to produce is not.

Code and jurisdiction

There is no nationwide building code for site-built houses. States and local governments adopt model codes, amend them, and set their own permit and inspection procedures, so the same work produces different requirements a county line apart. The three jurisdictions cited on this page illustrate the spread. Seattle put its 2021 construction codes into effect on 15 November 2024; that adopted residential code defines roof replacement as removal down to the deck (R908.3) and requires an ice barrier in areas with a history of ice forming along the eaves (R905.1.2). Arvada, Colorado, working from the 2018 IRC and IBC, publishes that an ice barrier is not required and that venting is not inspected on a re-roof where it met the code in effect at original construction. Unincorporated Santa Cruz County, California runs a separate tear-off inspection and sheathing inspection, with an in-progress re-roof certificate that can be used in lieu of both.

Three jurisdictions, three answers, all of them correct where they apply. The practical consequence is that “the code says” is not a sentence anyone can finish for your building without naming your jurisdiction and its adopted edition.

Every code statement on this page names the jurisdiction that adopted it, its edition, and the date the text was checked. None of them is a determination about your building, and a citation to model IRC language through an adopting city is still a citation to a model provision, not to the law where you live. The authority having jurisdiction over your address is the only body that can tell you what your permit, inspections, and ice-barrier requirement actually are.

Structural weight

A pallet of shingles is a concentrated load. The 2021 Seattle Residential Code (R908.2), in effect there since 15 November 2024, requires the structural roof components to be capable of supporting the roof covering system plus the material and equipment loads encountered during installation, which is a design-side requirement rather than something a crew calculates on the day; in practice competent crews spread bundles rather than stack them in one place, and the manufacturer instructions for at least one major product line say plainly to lay bundles flat and not to bend them over the ridge. If the covering is changing to something substantially heavier, that is not a staging question at all — it is a structural evaluation, done by a licensed engineer for that building, before the contract is signed.

Moisture and ventilation

A replacement is the one moment when the ventilation strategy is cheap to change, which is why it gets changed casually and wrongly. There is no national ratio, but the shape of the rule is worth seeing once in a real adopted text. The 2021 Seattle Residential Code (R806.2) sets a minimum net free ventilating area of 1/150 of the vented space, and allows 1/300 only whereboth of two conditions are met: a Class I or II vapor retarder on the warm-in-winter side in climate zones 6 through 8, and between 40 and 50 percent of the required area provided by ventilators in the upper portion of the space, with the balance in the bottom third. The same code (R806.3) also requires not less than a one-inch space between insulation and the roof sheathing at eave vents, which is the requirement blocked soffits actually violate. What your own jurisdiction has adopted may differ in every one of those particulars.

Adding a ridge vent while leaving the old box vents or a powered fan in place is the common field error: the ridge takes the path of least resistance and pulls air from the nearest opening rather than from the soffits, and the intake half of the system does nothing.

There is no universal ventilation ratio and no rule that more ventilation is always better. A correctly designed unvented assembly is a legitimate approach that the same Seattle text expressly permits under stated conditions (R806.5), and converting a vented attic to an unvented one — or the reverse — is an assembly decision involving insulation, air sealing, and vapor control, not a roofing accessory decision.

Climate

Season changes what “finished” means. Asphalt shingles seal by thermal activation of a factory-applied adhesive strip, and one manufacturer’s current technical bulletin states directly that shingles installed in cold weather may not seal until warmer temperatures arrive, that extra care is needed at or below 40°F, and that every shingle on the roof perimeter should be hand-sealed — four one-inch dabs of an ASTM D4586-compliant cement on laminate shingles, two under each tab on three-tab — when it is too cold for the strip to activate. A winter roof that has not sealed is not defective; it is unsealed, and it is more vulnerable to wind until it seals. Whether the perimeter was hand-sealed is a fair question to ask in January and a pointless one in July.

Wind

Wind performance during and after a replacement is decided by attachment, not by a number on a wrapper. The 2021 Seattle Residential Code ties the required shingle wind classification to the ultimate design wind speed for the site (R905.2.4.1) and sets a fastener minimum — not fewer than four per strip shingle — that defers upward to the manufacturer’s approved instructions (R905.2.6); the product instructions in turn specify where in the shingle the nails must land and how far they must penetrate the sheathing. Nails placed above the marked area, or driven at an angle, leave the course below effectively unattached regardless of what the shingle is rated to.

A marketing “mph rating” on a package is not a code determination for your building. Wind design depends on the site’s basic wind speed, exposure, building height and geometry, pressure zone, enclosure classification, risk category, and the tested assembly — none of which a covering carries with it.

Hail and impact

If hail is the reason for the replacement, the impact class of the new covering is worth understanding precisely. IBHS describes the UL 2218 test as two impacts in the same location, with the product passing if no crack is visible on the back of the shingle, and states plainly that these standards evaluate new products and do not account for the effects of weathering, temperature, aging, or similar factors.

“Class 4 impact resistant” does not mean hail proof. It is a laboratory result on a new sample under a defined test, not a prediction about a fifteen-year-old roof in a real storm — and some insurers offer premium credits for it, which is a financial argument rather than a performance guarantee.

Fire

Proposals sometimes describe a shingle as “Class A.” The 2021 Seattle Residential Code (R902.1) requires Class A, B or C roofing in jurisdictions designated by law as requiring their use, or where the edge of the roof is less than three feet from a lot line, and requires roofing that section requires to be listed to be tested in accordance with ASTM E108 or UL 790. Whether either trigger applies at your address is a question for your building department, not for a proposal.

Fire classification applies to a tested assembly — deck, underlayment, and covering together, as listed — not to the covering by itself. Changing the underlayment to a cheaper product than the listing calls for can change the assembly the classification was based on, which is one more reason the underlayment product belongs in the written scope by name.

Warranty and repair

What is covered, and what can actually be repairedSection link

There are usually three separate promises on a roof replacement, they are made by different parties, and only one of them is likely to be tested in the first five years.

Manufacturer material warranty: Made by whoever made the shingle, and generally about manufacturing defect in the product rather than about how it was installed. Note what this excludes by construction: a shingle that never sealed because it was installed in cold weather and the perimeter was not hand-sealed is a failure of the installation sequence, not evidence of a defective product.
Enhanced or system warranties: Longer or broader coverage offered when a registered installer uses a specified set of accessories from the same manufacturer — starter, underlayment, ice barrier, ridge, and sometimes ventilation. If one of those is substituted at delivery, the roof may be perfectly good and the enhanced warranty may not exist. This is the practical reason to check the delivery against the contract on day one, and it is why the specific warranty being purchased should be named in the proposal.
Workmanship warranty: Made by the contractor, covering their own installation, and worth exactly as much as the contractor’s continued existence and willingness to return. Get it in writing with a start date, and ask what it covers that the manufacturer warranty does not. The division matters because the two documents answer different questions: a material warranty is about defect in the product, while a leak at a wall, a chimney, or a pipe penetration is an installation question, and only the contractor’s document addresses that.
What tends to void coverage: Installation contrary to the manufacturer’s published instructions. One current instruction sheet states that the manufacturer will not be responsible for problems resulting from any deviation from the application instructions and its listed precautions. That includes fastener type and placement, keeping the deck dry before, during, and after installation, minimum deck thickness, and ventilation complying with local code.

Repairability

The first repair on this roof will happen sooner than the first warranty claim, and it will go better if you can name the product. Record the exact shingle line and color, the accessories used, and the installation date at closeout. Color lots shift over time, so a repair five years out may be visibly different even in the same product.

Ask whether leftover bundles stay on site. A few spare bundles stored flat and dry are the cheapest insurance available against a future patch that does not match, and they cost the contractor nothing to leave behind if you ask before the truck is loaded.

A warranty is a contract between a reader and whoever wrote it. What it covers, what voids it, whether it transfers, and how it is enforced are set by that document and by the law where the reader lives. Read the actual warranty for the product and the installer in front of you — not a summary of one, including this one.

Ask before you sign

Questions to ask an installerSection link

These are ordered by when they stop being useful. Everything in the first group has to be settled before signing; by day two, several of them are unanswerable.

What is your unit price for deck sheathing replacement, how many sheets are included in the contract price, and are partial sheets billed as whole sheets?
This is the single question with the largest financial spread on the whole project, and it is the only one that becomes unnegotiable the moment the roof is open. A good answer is three numbers and a thickness. A bad answer is “we will take care of you.”
Will you photograph the bare deck and the flashings before covering them, and send me the photographs the same day?
It costs a crew two minutes and it converts the two uncheckable stages into a record. Reluctance here is informative out of all proportion to the size of the request.
Which flashings are being replaced and which are being reused — step, counter, valley, pipe boots, chimney, kickout?
The 2021 Seattle Residential Code requires flashings to be reconstructed in accordance with approved manufacturer’s installation instructions (R908.6), and requires existing flashings, edgings, outlets and vents that are rusted, damaged or deteriorated to be replaced (R908.5). Whether your jurisdiction has adopted the same language is a question for your building department. Either way, step flashing is buried in the wall and cheaper to leave, so get the answer per location, in writing.
Which permit are you pulling, in whose name, and which inspections does this jurisdiction require?
A contractor who works in your area knows the answer without looking it up. A permit pulled in your name shifts responsibility to you. An open permit surfaces years later at resale.
What underlayment product, and where exactly does the ice barrier start and stop?
“Synthetic underlayment” is a category, not a product, and the specific product can matter to an enhanced warranty and to a fire listing. Ice-barrier extent is measured inside the exterior wall line where it is required at all, which is further up the roof than the fascia most crews stop at.
What is the ventilation plan, and what happens to the existing vents?
The answer you want names both halves — intake and exhaust — and says what is being removed. If the answer is only “we are adding a ridge vent,” ask what the soffits look like and whether the old box vents are being closed off.
What nails, what length, how many per shingle, and does that match the manufacturer’s instructions for this product?
The 2021 Seattle Residential Code sets a floor — fasteners long enough to penetrate not less than 3/4 inch into the sheathing (R905.2.5), and not fewer than four per strip shingle (R905.2.6) — and then defers upward to the manufacturer’s approved instructions, so the product’s own sheet governs. A crew that cannot answer this is not working from the instruction sheet.
If we lose days to weather, what does the roof look like overnight, and who decides when to stop?
You are asking whether they open more roof than they can dry in. The answer should describe sections, not optimism about the forecast.
What is the cleanup standard, and how many magnet passes, over what area?
“We clean up” is not a standard. Beds, lawn, and the strip behind the dumpster are where nails are found for the next two years.
What exactly do I receive at closeout, and what triggers final payment?
Final payment is the only leverage that exists after the crew leaves. Tie it to the closed permit and the delivered document package rather than to the last shingle.

Require these in writing

Tear-off: number of existing layers included, and the price to remove an unexpected additional layer
Disposal: dumpster or trailer, where it will be placed, and driveway protection
Deck replacement: unit price, included quantity, panel type and thickness, partial-sheet billing, and photograph requirement
Underlayment: product name, and the fastening pattern if the manufacturer specifies one
Ice barrier: product, and the measured extent at eaves, valleys, and any low-slope area
Drip edge: at eaves and rakes, metal type and color
Flashing: replaced or reused, listed per location — step, counter, valley, pipe boots, chimney, skylight, kickout
Shingle: exact product line, color, and the fastener type and count being used
Ventilation: intake and exhaust products, what is being removed, and what is being added
Permit: who pulls it, whose name it is in, who pays the fee, and which inspections are included
Cleanup: magnet passes, area covered, and the debris removal date
Warranty: the exact manufacturer warranty being purchased, who registers it, and the workmanship term and start date
Payment: schedule, deposit, and the specific event that triggers final payment
Change orders: written, priced, and approved before the work is performed — not after

What goes wrong

Misconceptions and failure modesSection link

These are the beliefs that cost the most money, in roughly that order.

Common misconceptions

Common belief
The permit is the contractor’s paperwork. It has nothing to do with me.
What is actually true
The permit is issued against your property, and the inspection it triggers is the only independent look anyone takes at this work. A permit left open does not expire quietly; it turns up in a municipal or title search when you sell, at which point closing it may require exposing work that has been covered for years.
Common belief
They finished in one day, so they must be good.
What is actually true
Duration is a function of roof area in squares, number of existing layers, crew size, geometry, access, and weather — not of quality. A small simple roof finished in a day by a large crew is unremarkable. The checkable question is not how fast they went; it is whether the roof was at a complete lap and watertight at the end of every day, and whether anyone stopped at the deck to talk to you.
Common belief
They are replacing the roof, so obviously the flashing is new.
What is actually true
Only if the contract says so. Step flashing runs up behind the siding, so replacing it means disturbing the wall; reusing it is cheaper and faster and invisible. A leak that appears at a wall or a chimney after a new roof is a flashing question rather than a shingle question, which is why the flashing line in the proposal deserves at least as much attention as the shingle brand.
Common belief
We added a ridge vent, so the attic is ventilated now.
What is actually true
Exhaust without intake is not ventilation, it is a hole. There is no national ratio to quote, but the adopted texts that do set one pair the two halves: the 2021 Seattle Residential Code allows the more generous 1/300 rate only where between 40 and 50 percent of the required area sits in the upper portion of the space and the balance sits in the bottom third (R806.2), and it requires not less than a one-inch space between insulation and roof sheathing at eave vents (R806.3). Your jurisdiction may have adopted something different, or nothing comparable at all. If the soffits are blocked, painted shut, or never cut in behind the perforated panel, the ridge vent will happily draw its air from whatever other opening is nearest — including the old box vents that were left in place.
Common belief
Ice and water shield over the whole roof is always the safer choice.
What is actually true
It is a legitimate approach in some assemblies, and IBHS describes a sealed roof deck as a way to keep water out when the covering itself is damaged. It is also a change to how the assembly dries, which interacts with insulation, air sealing, and ventilation, and it is not a universal upgrade you can add to any roof without thinking about the attic underneath it. Where it is required at the eaves, that requirement is set by your adopted code and climate, not by a preference.
Common belief
They ran the magnet, so the nails are gone.
What is actually true
A rolling magnet lifts steel. It does not lift aluminum or copper fasteners, and it does not reach nails that have been trodden into turf, gravel, or mulch. One pass in one direction across the driveway is the version most people get. Ask for multiple passes, in more than one direction, across the beds and lawn as well — before final payment, while asking is still easy.

How it actually fails

Nails above the nailing area (“high nailing”): Fasteners driven above the marked strip land in the shingle above only, leaving the course below held by the sealant strip alone until the wind finds it. Manufacturer instructions specify the fastening area precisely for this reason.What you can see: Rarely visible from the ground once the roof is complete. It is visible in a photograph taken during installation, and it shows up later as courses lifting or sliding in an unremarkable wind event.
Over-driven and under-driven fasteners: An over-driven nail cuts through the shingle mat and holds nothing; an under-driven nail stands proud, interferes with the course above sealing flat, and works its way back out. Product instructions require penetration of a stated depth into the sheathing, or fully through a thin deck.What you can see: Small raised bumps in an otherwise flat course, visible in raking light from the ground; nail heads appearing on the surface of the roof after a season or two.
Continuous “L” metal instead of step flashing: A single long bent strip laid along a roof-to-wall intersection and sealed at the top, in place of individual pieces woven one per shingle course. Water that gets behind it has a continuous path downward, and the sealant that is holding it out is the only thing standing between the wall and the water.What you can see: From the ground: an unbroken line of metal where a wall meets a roof, with caulk at the top, rather than the stepped pattern of overlapping pieces. Interior sign: staining that appears at the wall a course or two below the intersection, worst in wind-driven rain.
Underlayment run under the eave drip edge: Reversing the lap order at the eave. Water on top of the underlayment then runs behind the drip edge instead of onto it, and drains onto the fascia and into the soffit.What you can see: Visible during installation, in the figure above. Later: paint failure, staining, or softness along the fascia board and the soffit under a specific eave, without any leak inside the house.
Ice barrier stopped at the fascia line: Where an ice barrier is required, the adopted text measures its extent from the lowest edges of all roof surfaces to a point inside the exterior wall line — up the roof slope, past the wall below. In the 2021 Seattle Residential Code that distance is not less than 24 inches (R905.1.2); your jurisdiction may set a different one or none at all. Stopping the membrane at the edge of the overhang leaves it short of the heated wall, which is exactly where backed-up water reaches.What you can see: Not visible after completion. Checkable only in an installation photograph, or by comparing the written scope against the requirement your jurisdiction publishes.
Shingles installed over a wet or frosted deck: Moisture trapped between deck and underlayment has nowhere fast to go. One manufacturer’s instructions direct the installer to prevent the wood deck from getting wet before, during, and after installation.What you can see: Nothing from outside. It shows up months later as sheathing staining or fastener corrosion, and is one of the reasons crews stop working in rain rather than pushing through it.
Reused pipe boots: The rubber collar around a plumbing vent degrades under UV long before the shingles do. A boot left in place at replacement puts a fifteen-year-old rubber part at the center of a brand-new roof.What you can see: Visible from the ground with binoculars or in a zoomed photograph: a cracked, cupped, or split collar around a vent pipe, often with sealant smeared over it.
Deck replacement that does not land on framing: A cut-in patch that stops mid-bay has no support at its edges. The sheet flexes underfoot and under snow load, fasteners along the unsupported edge loosen, and the seam telegraphs through the shingles.What you can see: Visible in the deck photograph as a patch whose edges do not sit over a rafter. Later, from the ground: a soft-looking dip or a straight line showing through the finished roof surface.

Sources and further readingSection link

Understanding Roofing

Scope and limitations

It cannot tell you what your jurisdiction requires.
The code sources here are one city’s adopted residential code and the published procedures of two other jurisdictions.
They are evidence of how much the answer moves, not the law where you live.
Your building department is the only authority on your permit, your inspections, and your ice-barrier requirement.
It publishes no dollar figures for roofing work.
The deck example uses arithmetic and two arbitrary unit prices to show what a contract clause is worth; neither number is an estimate of any market price, and this site has no sourced cost dataset for deck sheathing.
It cannot tell you how long your project will take.
Duration is set by roof area in squares, existing layers, crew size, geometry, access, and weather windows, and no honest average exists across those variables.
It is written for a steep-slope asphalt shingle replacement on a house.
The permit, deck, cleanup, inspection, and closeout stages carry over to tile, slate, metal, and residential low-slope work; the middle stages do not.
It cannot replace the manufacturer’s instructions for the product on your roof.
Fastener count and placement, starter requirements, and cold-weather handling are product-specific, and the sheet in the bundle governs.
It has not been technically reviewed, and no individual author is credited.
Both are prerequisites for this page being registered for indexing.

2021 Seattle Residential Code, Chapter 9 — Roof Assemblies
City of Seattle · Seattle Department of Construction and Inspections / 2021 edition, as adopted by the City of Seattle — effective 15 November 2024
The reroofing sequence as one jurisdiction has adopted it: tear-off down to the deck (R908.3); when a recover is not allowed, including water-soaked or deteriorated roofing and two or more existing applications (R908.3.1.1); construction and equipment loads during installation (R908.2); replacing rusted, damaged, or deteriorated flashings, edgings, outlets, and vents rather than reusing them, and reconstructing flashings per manufacturer instructions (R908.5, R908.6); solid sheathing for asphalt shingles (R905.2.1); fastener penetration of not less than 3/4 inch into the sheathing and the four-fastener-per-strip-shingle minimum deferring upward to manufacturer instructions (R905.2.5, R905.2.6); the wind classification tied to ultimate design wind speed (R905.2.4.1); ice-barrier extent measured not less than 24 inches inside the exterior wall line (R905.1.2); drip-edge lap order at eaves and rakes (R905.2.8.5); and the Class A/B/C fire requirement tested in accordance with ASTM E108 or UL 790 (R902.1).
Seattle’s adopted code, amended locally from the model text. It is not the law in any other jurisdiction. Confirm the adopted edition and amendments with the authority having jurisdiction over your building.
2021 Seattle Residential Code, Chapter 8 — Roof-Ceiling Construction
City of Seattle · Seattle Department of Construction and Inspections / 2021 edition, as adopted by the City of Seattle — effective 15 November 2024
Attic ventilation as one jurisdiction has adopted it: the 1/150 minimum net free ventilating area and the conditions under which 1/300 is allowed, including the 40-to-50-percent upper-portion requirement (R806.2); the one-inch clearance between insulation and sheathing at eave vents (R806.3); and the conditions under which unvented attic and unvented enclosed rafter assemblies are permitted (R806.5).
Same jurisdictional limit. Sections marked [W] are Washington State amendments, so even this text is not the unmodified model provision.
2021 Seattle Code Adoption — Timeline
City of Seattle · Seattle Department of Construction and Inspections
The effective date this page attaches to every Seattle code citation: “The 2021 editions of the Seattle construction codes went into effect on November 15, 2024.”
Records the effective date only. It is not the code text, and it says nothing about any other jurisdiction’s adoption schedule.
Re-Roofing — permit and inspection requirements
City of Arvada, Colorado · Building Inspection Division
That the same model code family produces different local answers: Arvada adopts the 2018 IRC and IBC, states that an ice barrier is not required, states that venting is not inspected on re-roof projects where it met the code in effect at original construction, requires a final roofing inspection on every re-roof permit plus a mid-roof inspection for flat and specialty materials, and sets its own gap threshold above which spaced sheathing must be replaced with solid sheathing.
Applies in Arvada, Colorado only. Cited here as evidence that jurisdictions differ, not as guidance for anywhere else.
Re-roofing Permit and Inspection Procedures
County of Santa Cruz, California · Community Development and Infrastructure
A third inspection regime: a tear-off inspection performed after removal of old roofing and before any sheathing is covered, a separate sheathing inspection before new sheathing is covered, an in-progress re-roof certificate that can be used in lieu of both, a final inspection covering fasteners, flashings, vents and drains, and a permit exemption for maintenance and for structures under 120 square feet.
Applies in unincorporated Santa Cruz County, California only, and the permit exemption thresholds quoted are that county’s own.
29 CFR 1926.501 — Duty to have fall protection
U.S. Occupational Safety and Health Administration
That employees engaged in residential construction six feet or more above lower levels must be protected by guardrail, safety net, or personal fall arrest systems — the reason a competent crew has visible fall protection and an untrained resident has none.
Federal employer duty under OSHA. It governs what an employer owes its workers; it is not permission, guidance, or a standard of care for a building’s occupants, who should not be on the roof at all.
Fall Protection — Overview
U.S. Occupational Safety and Health Administration
The characterization used in the safety callout: “Falls are among the most common causes of serious work related injuries and deaths.”
A general hazard statement, not a ranked fatality statistic. This page does not claim a share or a rate, because the cited page publishes neither.
Asphalt Shingle Roofs — retrofit and new construction guidance
U.S. Department of Energy · Building America Solution Center (PNNL)
The retrofit sequence: removing all existing roofing including shingles and underlayment, replacing damaged wood sheathing, and inspecting and re-nailing roof deck attachment fasteners to meet current requirements; plus drip edge at eaves and rakes and the practice of sealing roof sheathing seams.
Best-practice guidance for durable construction, not adopted code. It does not establish a requirement anywhere.
Roof 101
Insurance Institute for Business and Home Safety (IBHS)
That a sealed roof deck is intended to keep water out even when the roof cover is damaged; that wind can lift unsealed shingles and water can seep underneath before the sealant activates; and the UL 2218 impact test as described there — two impacts in the same location, passing if no crack is visible on the back of the shingle — together with the statement that these standards evaluate new products and do not account for the effects of weathering, temperature, aging, or similar factors.
FORTIFIED is a voluntary standard, not a code requirement. An impact classification is a laboratory result on a new sample, not a prediction about an aged roof in a real storm.
Duration Series Shingles — Installation Instructions
Owens Corning Roofing — product-specific installation instructions / Publication 10014283-L, July 2026
Product-specific requirements a crew works to: checking local building codes before installation; minimum deck thickness for plywood, OSB, and boards; preventing the wood deck from getting wet before, during, and after installation; fasteners penetrating at least 3/4 inch into the deck or fully through a thin one; placing fasteners in the marked fastening area; properly versus improperly driven nails; laying bundles flat and not bending them over the ridge; ventilation complying with local codes; and the statement that the manufacturer will not be responsible for problems resulting from any deviation from the instructions.
One manufacturer, one product line. The instructions that govern any particular roof are the ones printed on the wrapper of the shingle actually being installed.
Cold Weather Shingle Installation — Technical Bulletin
Owens Corning Science and Technology, LLC — technical bulletin / Publication 10022497-A, April 2026
That shingles installed in cold weather may not seal until warmer temperatures activate the sealant and may take longer to lie flat; that extra care applies at or below 40°F; and that every shingle along the entire roof perimeter should be hand-sealed with ASTM D4586-compliant asphalt roof cement — four one-inch dabs on laminate (architectural) shingles, two under each tab on strip (three-tab) shingles — to protect against wind uplift when it is too cold for the adhesive strip to activate.
Product-specific, and specific to this manufacturer’s shingles. Another product’s cold-weather procedure may differ.
Protect Your Family from Exposures to Asbestos
U.S. Environmental Protection Agency
That you generally cannot tell whether a material contains asbestos by looking at it unless it is labeled; that material in good condition which will not be disturbed should be left alone; and that repair or removal of damaged material needs a trained and accredited asbestos professional, because improper removal can increase exposure.
General homeowner guidance. It does not identify which roofing products in a specific building contain asbestos, and it is not a substitute for a professional inspection.
How do I know if I have asbestos in my home (floor tile, ceiling tile, shingles, siding, etc.)?
U.S. Environmental Protection Agency
That the only way to be sure whether a material contains asbestos is laboratory testing; that EPA recommends testing suspect materials when they are damaged or when a renovation would disturb them; and that samples should be taken by a properly trained and accredited inspector.
General guidance; it does not name a construction date after which roofing products are asbestos-free.

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