What is included in a roof replacement?
A full replacement includes tear-off and disposal, deck inspection, synthetic underlayment, ice-and-water membrane, starter course, new drip edge, all new flashing and pipe boots, the shingle, hip and ridge cap, ridge ventilation, permit, inspection and a magnet sweep. Our rate is $600 to $900 per square, $19,000 to $31,000 on a typical 24-square house.
Every line item, and what it is for
| Line item | What it is | What happens without it |
|---|---|---|
| Tear off and haul away | Every existing layer stripped to bare deck, loaded and disposed of. | A roof laid over the old one runs hotter, hides the deck condition and loses years. |
| Deck inspection and repair | Every sheet checked; rotten or delaminated sheathing replaced at $120 per 4x8 sheet, photographed first. | Nails driven into soft board hold nothing. This is the most common discovered item on any roof past twenty. |
| Drip edge | New code-required edge metal at eaves and rakes. | Water runs behind the gutter and rots the fascia behind a brand-new roof. |
| Ice-and-water membrane | Self-adhering barrier at eaves and in all valleys, sealing around every fastener. | Ice damming in a Maryland freeze-thaw winter pushes water back up under the shingles. |
| Synthetic underlayment | Full-coverage secondary barrier over the whole deck. | Felt tears in wind during the install and is a downgrade the manufacturer system warranty usually will not accept. |
| Starter course | Purpose-made starter strip at eaves and rakes. | Cut-up shingle used as starter puts the sealant in the wrong place and the perimeter blows off first. |
| Shingle | The visible product, by manufacturer and line, nailed in the specified zone. | Nails outside the zone void the wind rating regardless of what the packet says. |
| All new flashing | Step, counter, apron, valley metal, pipe boots at $65 each and any chimney re-flash at $600. | Reused flashing is the single most common leak under a new roof, and no warranty covers it. |
| Hip and ridge cap | Matching purpose-made cap, not cut-up field shingle. | Cut caps crack at the fold and the ridge is the highest-uplift line on the roof. |
| Ventilation | Continuous ridge vent, balanced against intake, cut in at $15 per foot where it does not exist. | An unventilated attic bakes the shingle from underneath and voids most manufacturer warranties. |
| Permit and inspection | County permit and third-party inspection where required. | No independent check on the work, and a problem at resale. |
| Cleanup and magnet sweep | Debris removed and the property swept magnetically for nails. | Nails in the driveway and the lawn, found by tyres and feet. |
Four of those are the ones that disappear on a cheap bid, and they are the same four every time: the tear-off (replaced by an overlay), the ice-and-water membrane, the new flashing, and the ventilation. Each is invisible from the street once the job is done, each is the difference between a roof reaching its warranty and not, and together they are most of the gap between a bid at half our price and ours.
What it costs, and what a calculator cannot see
The owner-published band is $600 to $900 per square for a roof replacement, where a square is 100 square feet of roof area. Taken as a complete job with everything above included, our rate lands at $788 to $1,300 per square, which on a typical 24-square Maryland house is $19,000 to $31,000. The field rate for architectural shingle alone — the line item, not the job — is $784 per square in the Baltimore-index counties and $848 in the Washington metro.
Why the two numbers differ, since it confuses people and it should not. $784 per square is the shingle assembly: tear-off, shingle, underlayment and ice barrier. $788 to $1,300 is the whole job, carrying edge metal, ridge, ventilation, flashing, permit and cleanup as well. Both are honest and both are labelled everywhere they appear on this site. A quote that shows you the first number and charges the second is the trick this is written to make impossible.
What no calculator can see, and therefore what no calculator price survives contact with: how many layers are up there, whether the deck is sound, the pitch, the number of penetrations, whether the chimney flashing is original, whether the ventilation meets code, and how much of the roof is edge rather than field. A cut-up roof with six dormers costs far more per square than a simple gable of the same area, and that is not a pricing decision, it is arithmetic about how much of the job is hand-work.
How to estimate your own roof replacement cost
This is the arithmetic a contractor does. It will not be exact, and it will stop you being surprised.
- Measure the footprint Take the outside dimensions of the house from a satellite view or a tape and work out the ground-floor area in square feet. Include the garage and any covered porch with a shingled roof over it.
- Add for pitch and overhang A roof is bigger than the house under it. Add about 10 percent for a shallow roof, 20 percent for a typical Maryland gable, and up to 30 percent for a steep or cut-up roofline with dormers. This is the step people skip and it is why homeowner estimates come out low.
- Convert to squares Divide by 100. One roofing square is 100 square feet. A 2,400 square foot footprint plus 20 percent for pitch is 2,880 square feet, which is 28.8 squares.
- Multiply by the rate Use $600 to $900 per square for architectural asphalt. The lower end applies in the outer Maryland counties on a simple roofline; the Washington metro sits at the upper end.
- Add for what is known in advance A second existing layer is an adder of $95 per square, steep pitch above 8/12 is an adder of $90 per square, and a chimney re-flash is $600. These are known from a measurement rather than discovered.
- Then have it measured Everything above is a ballpark that gets within a few thousand dollars. What it cannot see is soft decking, priced at $120 per sheet, or a skylight at end of life. Those are found on the roof, and they are the difference between an estimate and a price.
Scope and cost questions
What is included in a roof replacement?
Tear-off of every existing layer and disposal; inspection of the deck and replacement of any rotten sheathing at a published per-sheet rate; new drip edge at eaves and rakes; ice-and-water membrane at the eaves and in the valleys; full synthetic underlayment; purpose-made starter course; the shingle itself nailed in the manufacturer specified zone; all new flashing including step, counter, valley and pipe boots; matching hip and ridge cap; ridge ventilation balanced against intake; the county permit and inspection; and a full cleanup with a magnet sweep for nails.
What is the average cost of a roof replacement?
Our published band is $600 to $900 per square, where a square is 100 square feet of roof area. As a complete job the rate is $788 to $1,300 per square, which on a typical 24-square Maryland house comes to $19,000 to $31,000. That is a retail list range from our published price book rather than a quote: the real number depends on the measured area, the pitch, how many layers are up there, the condition of the deck and how much of the roof is detail rather than open field.
Why is my quote so much cheaper than that?
Usually because it is a smaller job. The four items that disappear from a cheap bid are consistently the same: the tear-off, replaced by laying new shingles over the old; the ice-and-water membrane; new flashing, replaced by reusing what is there; and the ventilation. None of the four is visible from the street after the work is done, and all four decide whether the roof reaches its warranty. Compare the scopes rather than the totals and the gap usually explains itself.
Is the permit included in the price?
On our estimates the permit and inspection are a named line rather than something folded into a total, so you can see what it costs and confirm it is being pulled. Most Maryland counties require a permit for a full replacement, and the value of it is the independent inspection rather than the paperwork. A bid that is cheaper because no permit is being pulled is cheaper because nobody will check the work.
What happens if you find rotten decking?
It is photographed sheet by sheet before anything is covered, and it is charged at the published rate of $120 per 4x8 sheet — a number that is on the estimate before the job starts rather than negotiated on the roof. Nothing is replaced without your written approval, with the photograph of the condition attached. Where a whole roof needs re-decking over failed skip sheathing, that is an adder of $4.50 per square foot on top of the roof price, and it is normally identified at the inspection rather than discovered.
Do you replace the gutters at the same time?
Where they are due, yes, and it is the right sequence. Drip edge, gutter apron and the first course of shingle all have to lap in a specific order for water to leave the roof and land in the gutter rather than behind it, so fitting a gutter to a roof that is about to be torn off means paying for the same crew twice. Where the gutters are sound, they are protected during the tear-off and left alone.
Where to go next
This is the scope. These pages cover what it costs where you live and how to compare two of them.
How to read a roofing estimate
What the price is made of, the seven places a cheap bid gets cheap, and how to compare two quotes line by line.
Read the standard →CostRoof replacement cost in Maryland
The statewide cost guide: per square, per square foot, and what a typical house lands at.
See the numbers →ToolInstant roof quote
A real number off your own roof measurement in about a minute, from the same price book this page quotes.
Get the number →TimingHow long a roof replacement takes
Day by day, what weather delays, how long the permit takes, and what happens when the deck opens up.
Read the guide →