Updated August 19, 2026. Superior Roofing, 525 Riverside St, Portland, ME 04103. Call 207-702-7663 for a free estimate.
Direct Answer
Rolled asphalt roofing is mineral-surfaced asphalt sheeting installed on low slope roofs. In Portland, Maine it costs roughly $2.00 to $5.50 per square foot installed and lasts 5 to 10 years. Code permits it on slopes of 1:12 or greater, which suits sheds, garages, and porch roofs.
TL;DR
- Code permits mineral-surfaced roll roofing only on slopes of 1:12 or greater. Asphalt shingles need 2:12, so the 1:12 to 2:12 band is where rolled asphalt earns its place [1].
- Installed cost runs about $2.00 to $5.50 per square foot, roughly half of rubber or shingles [2].
- Standard product lasts 5 to 10 years. Modified bitumen in the same family reaches 10 to 20 [7].
- Use it where no heated living space sits underneath. Sheds, detached garages, and porch roofs are the strong fits.
- Maine requires an ice barrier at the eaves for this material, and a quote that omits it is incomplete rather than cheap [1].
- Cheapest per square foot, roughly double the cost per year of a longer-lived system. That trade only works on structures you will re-cover anyway.
One liner: Rolled asphalt is the correct material for low slope outbuildings and the wrong one for anything you plan to keep.
Key Numbers
| Metric | Figure | Source |
|---|---|---|
| Minimum slope, mineral-surfaced roll roofing | 1:12 | 2021 IRC R905.5.2 [1] |
| Minimum slope, asphalt shingles | 2:12 | 2021 IRC R905.2.2 [1] |
| Minimum slope, GAF Mineral Guard product | 2:12 | GAF product specification [9] |
| Installed cost per square foot | $2.00 to $5.50 | HomeGuide national range [2] |
| Service life, standard product | 5 to 10 years | Industry range, varies by source [7] |
| Service life, modified bitumen | 10 to 20 years | Industry range, varies by source [7] |
| Coverage per roll | About 100 sq ft, one roofing square | HomeGuide [2] |
| Weight per roll | 50 to 75 pounds | National guide figure [11] |
| GAF warranty claim window | 5 years from installation | GAF limited warranty [8] |
| MUBEC enforcement threshold | Municipalities of 4,000 or more residents | Maine DOE [6] |
Cost and service life rows carry their source inline because they come from industry aggregators rather than code or manufacturer documentation. Weight them accordingly.
What Rolled Asphalt Roofing Is (and What It Is Not)
In short: Rolled asphalt roofing is the same asphalt-and-granule material used in shingles, manufactured as a continuous sheet instead of cut tabs. It covers low slope roofs quickly and cheaply, and it is built for outbuildings rather than main house roofs.
Picture an asphalt shingle stretched flat and wound into a roll. That is close to the truth. Both products start from an asphalt-saturated mat with mineral granules pressed into the top surface. The difference is format. Shingles arrive as cut tabs you overlap in courses. Roll roofing arrives as one long sheet you run horizontally across the deck, which is why a crew can dry in a garage roof in an afternoon.
One roll measures roughly 36 inches wide by 36 feet long and covers about 100 square feet, which the trade calls a roofing square [2]. That unit matters later, because contractors price by the square, not by the roll.
Two versions exist. Mineral-surfaced roll roofing carries the granule layer and serves as a finished roof surface. It has to conform to ASTM D3909 or ASTM D6380, Class M, and it has to be fastened to a solidly sheathed deck [1]. Smooth-surfaced roll roofing has no granules and works as underlayment or flashing, not as a finished surface. When a Portland contractor quotes rolled asphalt for your shed, they mean the mineral-surfaced product.
Here is what it is not. It is not a cheaper shingle you can put anywhere. It is a code-governed material with a defined slope range and a defined job. Calling it the budget option skips the part that actually decides whether it belongs on your building, which is the next section.
If you want the service side rather than the background, Superior’s rolled asphalt roofing page covers installation and repair directly.
Step One: Measure Your Slope (The 1:12 Rule)
In short: Mineral-surfaced roll roofing cannot go on a roof shallower than 1:12, meaning one inch of rise for every 12 inches of run [1]. Asphalt shingles need at least 2:12. That gap decides which material your roof can legally take.
You can check this yourself in five minutes. Hold a level against the roof surface, mark 12 inches along it, then measure straight down from the 12-inch mark to the roof. That drop is your rise. A four-inch drop means a 4:12 roof. Do it in two or three spots, because porch roofs and additions often differ from the main structure.
Now compare what you measured against what the code allows.
| Roof covering | Minimum slope | Code section |
|---|---|---|
| Built-up roof | 0.25:12 | R905.9.1 |
| Mineral-surfaced roll roofing | 1:12 | R905.5.2 |
| Asphalt shingles | 2:12 | R905.2.2 |
| Metal roof shingles | 3:12 | R905.4.2 |
Source: 2021 International Residential Code [1].
One caution on reading that table. Those are code minimums, and manufacturer instructions carry code force alongside them. A specific product may require more slope than the code floor, which the lifespan section covers.
The 1:12 to 2:12 band
Look at the gap between the second and third rows. Between 1:12 and 2:12, shingles are prohibited and rolled asphalt is permitted. That narrow band is where a lot of Portland porch roofs, additions, and detached garages land.
If a contractor told you no to shingle roofing on a structure you assumed was fine, this is almost always why. They were not upselling. The slope disqualified the material.
The rule exists because of drainage physics. Shallow roofs shed water slowly, water backs up under the covering, and intrusion follows. Steep roofs move water off before it finds a seam.
One installer note for the shallow end of the range. On slopes from 1:12 to 2:12, building departments applying the 2021 code recommend double-lapping the sheet at a 19-inch overlap rather than the standard narrow lap [3]. It costs more material and buys real margin on the roofs that need it most.
Step Two: Sheds, Garages, Porches, and Additions
In short: Rolled asphalt belongs on structures with no conditioned living space underneath. Sheds, detached garages, and porch roofs are strong fits. Additions and main house roofs usually are not, even when the slope technically allows it.
Slope tells you what is permitted. Structure tells you what is sensible. Those are different questions, and the second one is where most people go wrong.
Here is the dividing line that matters more than any other: is there heated living space under that roof?
A leak over a detached garage is a nuisance. You find it, you patch it, you move on. A leak over a bedroom is drywall, wet insulation, and a mold conversation. Rolled asphalt is a single-layer system with exposed seams, and it earns its low price by accepting a shorter service life and more seams than a shingle field. That trade is fine over a lawn mower. It is a poor trade over your kid’s bedroom.
| Structure | Typical slope | Verdict |
|---|---|---|
| Storage shed | 1:12 to 4:12 | Strong fit |
| Detached garage | 1:12 to 3:12 | Strong fit |
| Porch or entry roof | 1:12 to 2:12 | Strong fit, most common Portland case |
| Heated addition | 1:12 to 3:12 | Consider rubber instead |
| Main house roof | varies | Wrong material |
Porch roofs deserve their own note. They are low slope by design, they are small, nothing heated sits beneath them, and they usually tie into a main roof that stays shingled. That combination makes them the most legitimate rolled asphalt application in Portland by a wide margin.
For heated additions the calculus shifts. The slope may permit rolled asphalt, but living space underneath argues for a membrane. Rubber roofing costs more up front and gives you a seamless surface over the rooms you actually heat.
One more case worth naming honestly. If a structure is slated for demolition or replacement in a few years, rolled asphalt makes a reasonable bridge. Paying for a 30-year roof on a building with three years left does not serve you.
Step Three: Price It Against the Alternatives
In short: Rolled asphalt runs about $2.00 to $5.50 per square foot installed, roughly half the cost of rubber or shingles [2]. It is the cheapest way to cover a low slope roof today and often the most expensive per year on anything you plan to keep.
What rolled asphalt roofing costs in Portland
A word on where these numbers come from. Published rolled roofing prices are national figures from cost aggregators, not Maine market data, because no one collects rolled roofing pricing at the state level. Treat them as a range to check a quote against, not as your quote. Slope, access, deck condition, and tear-off move the final number more than the material does.
With that said, here is the landscape.
| Material | Installed cost per sq ft | Typical life | Approximate cost per year, per sq ft |
|---|---|---|---|
| Rolled asphalt | $2.00 to $5.50 [2] | 5 to 10 years | $0.50 |
| EPDM rubber | $4.00 to $10.00 [2] | 20 to 30 years | $0.28 |
| Architectural shingles | $4.75 to $7.50 [4] | 15 to 30 years | $0.27 |
That last column is the one worth sitting with. Rolled asphalt wins the sticker price and loses the decade. Spread across its service life, it costs close to double what a longer-lived system costs per year.
Which is fine, as long as the structure fits. On a shed you may sell with the house, cheapest today is the correct answer. On a porch tied into a roof you are keeping for twenty years, it is not.
A worked example
Take a 400 square foot detached garage, four roofing squares, measured at 1.5:12:
- Rolled asphalt: $800 to $2,200
- EPDM rubber: $1,600 to $4,000
- Architectural shingles: not permitted at that slope
The shingle line is the useful one. On low slope structures, the material most people assume is the default is not on the menu at all. The real comparison is rolled asphalt against rubber, and that is a genuine decision rather than a foregone one.
What a cheap quote leaves out
Watch for these line items, because their absence is what makes a lowball look competitive:
- Tear-off and disposal of the existing roof, which adds roughly $1 to $2 per square foot [2]
- Permit fees, commonly $150 to $500 [2]
- Decking repair, which nobody can price until the old roof is off
- Ice barrier at the eaves, which Maine requires and the code section below covers
For context on the other end of the scale, Superior’s 2026 Portland roof replacement pricing guide puts a full architectural shingle roof at $8,000 to $18,000 [4]. A rolled asphalt garage is a different order of project entirely.
The only number that means anything is a measured one. Get a free estimate and compare it against the ranges above.
What Maine Code Requires Before You Start
In short: Maine has adopted the 2021 International Residential Code as part of MUBEC [5]. For rolled asphalt in Portland, the requirement that changes your quote most is an ice barrier at the eaves.
The ice barrier at the eaves
In areas with a history of ice forming along the eaves and backing water up, an ice barrier is required for mineral-surfaced roll roofing [1]. Coastal Maine is not a borderline case.
Here is the mechanism. Snow on a roof melts from below where heat escapes the building. That meltwater runs down to the eave, which stays cold because there is no heated space beneath it, and refreezes into a ridge of ice. Water pools behind that ridge and moves uphill, under the roof covering, driven by nothing more than depth.
A steep roof gives water somewhere to go. A low slope roof does not, which is why the material best suited to shallow roofs also needs the most protection at the edge.
If a quote you are comparing came in noticeably low, this is the first line item to look for. A missing ice barrier makes a bid cheaper by making it incomplete.
Whether the code applies where you live
MUBEC has to be enforced in any Maine municipality with 4,000 residents or more [6]. Below that population, the town decides for itself.
Portland is the largest city in Maine, so this is settled here. It is a live question in smaller Cumberland and York County towns, and worth asking before you assume either way.
One caution. Enforcement and physics are different things. In a town that does not enforce MUBEC, an eave with no ice barrier still fails the same way, and it still turns up when a buyer’s inspector walks the property.
Permits and inspections
Reroofing permit requirements are set locally, not by the state, so the answer depends on your municipality. Call your local code enforcement officer before work starts. A reputable contractor pulls the permit as part of the job, and a contractor who suggests skipping it is telling you something useful.
Maine’s current code package took effect April 7, 2025 [5]. Work completed before then was held to an earlier edition, which matters if you are evaluating an existing roof rather than planning a new one.
How Long Does Rolled Asphalt Roofing Last?
In short: Standard mineral-surfaced roll roofing lasts roughly 5 to 10 years. Modified bitumen and torch-down products in the same family reach 10 to 20 [7]. Most of the confusion online comes from treating those as one product.
You will find published figures anywhere from five years to twenty. They are not all wrong. They are describing different materials.
Standard mineral-surfaced roll roofing, the budget product this article is about, sits at 5 to 10 years under normal conditions [7]. Step up to a modified bitumen or torch-down sheet and you are at 10 to 20, at a higher installed cost. When you compare quotes, check which one you are being quoted.
Maine’s climate pushes toward the lower end of whichever range applies. Freeze-thaw cycling causes asphalt to crack and split, and that is the dominant regional wear factor [7].
Two things fail first, and neither is the middle of the sheet. Seams are the weak point, because a 36-inch-wide sheet has to be lapped every few feet, and those laps can loosen over time [10]. Granule loss is the other, and it is your early warning: once granules wash off, the asphalt underneath oxidizes fast.
Fastening method matters as much as product choice. Exposed-nail installations, where the nail heads sit on the surface, typically deliver 5 to 8 years. Concealed-nail and fully adhered installations reach 8 to 12 [11]. Same material, four extra years, decided entirely by how it goes down. Ask which method you are being quoted.
Ponding water accelerates every failure mode above. Water that sits rather than drains degrades the material directly [10], which is why the shallow end of the 1:12 range needs drainage attention the steeper end does not.
Maintenance that actually extends it
- Clear debris, especially where it traps moisture against a seam
- Keep drainage paths open so nothing ponds
- Inspect seams and edges each spring after ice-out
- Patch punctures immediately rather than at the next inspection
- Consider a reflective coating on the mineral surface as the roof ages [10]
Superior handles rolled asphalt repair and maintenance if you would rather not walk a low slope roof yourself.
What the warranty actually covers
Set expectations here, because roll roofing warranties are thin.
GAF’s Mineral Guard roll roofing carries a limited warranty against manufacturing defects, and claims have to be filed within five years of installation [8]. That is a defect warranty, not a performance warranty. It covers a product that came off the line wrong. It does not cover a roof that reached the end of its service life, and it does not cover installation errors.
Installation is a separate document. Your contractor’s workmanship warranty is what covers a seam that was lapped wrong, and its terms come from the contractor, not the manufacturer. Ask for both in writing.
One detail worth catching before you sign anything: GAF specifies Mineral Guard for slopes of 2:12 and greater [9], which is steeper than the 1:12 code minimum. Manufacturer instructions carry code force, so on a 1:12 to 2:12 roof the product selection matters as much as the code table does. A contractor who knows this specifies accordingly.
The Three Situations Where It Is the Wrong Call
In short: Weighing rolled roofing pros and cons comes down to three disqualifiers. Heated space underneath, a roof you will keep past ten years, or a main roof anyone can see. Any one of them, and something else is the better buy.
Superior gives free estimates, so there is no cost to you in asking. But there is no reason to spend the afternoon on it if your roof falls into one of these.
- There is heated living space underneath.
The structure section covered the mechanics. A single-layer system with exposed seams is an acceptable risk over a lawn mower and a poor one over a bedroom. Additions, dormers, and finished bonus rooms all fall here. For those, rubber roofing gives you a seamless surface at a higher up-front cost and a much longer life.
- You plan to keep the roof more than ten years.
Run the cost math again. At 5 to 10 years of service life, rolled asphalt costs close to double per year what a longer-lived system costs. If you are covering a structure you will still own in fifteen years, you will pay for this roof twice or three times before the alternative needs replacing once. Cheapest today, most expensive by the decade.
- It is a main roof anyone can see.
This one is about the sale, not the leak. Rolled asphalt on a visible primary roof reads as deferred maintenance in a home inspection report, and the palette runs to black, white, tan, and gray, so matching a house is not on the table [11]. If your slope allows it, shingle roofing is the default for a reason. If you want the longest service life Maine’s weather allows, metal roofing sheds snow instead of holding it.
None of this makes rolled asphalt a bad product. It makes it a specific one. On a shed, a detached garage, or a porch roof you will re-cover again in a decade without thinking twice, it is the right answer and the cheapest way to get there.
Getting an Accurate Quote in Portland
In short: A complete rolled asphalt quote names the product, states the measured slope and square footage, and lists tear-off, disposal, and the ice barrier separately. Compare line items across estimates, not bottom lines.
Get three quotes. Then read them side by side rather than looking at the totals, because a lower number on this kind of job usually means a shorter list.
Here is what a complete estimate contains:
- Measured slope, not an eyeball estimate. It determines whether the material is even permitted.
- Square footage in roofing squares, so you can check the per-square math yourself.
- The product by name and grade. Standard mineral-surfaced or modified bitumen changes your service life by roughly a decade.
- The fastening method. Exposed nail or concealed nail changes service life again.
- Tear-off and disposal, priced as its own line.
- Ice barrier at the eaves, which Maine requires and whose absence makes a bid look cheaper.
- Both warranties, the manufacturer’s on the material and the contractor’s on the workmanship.
Two more things worth knowing before the numbers come back. Access and deck condition move the price more than the material does, so a tight backyard shed can quote higher per square than a drive-up garage. And nobody can price rotten decking until the old roof comes off, which is why a good estimate says how that gets handled rather than pretending it will not happen.
Small jobs also carry a floor. Many roofers set a minimum fee regardless of project size, commonly quoted nationally in the $500 to $800 range [11], which is why a 200 square foot shed can price closer to a 400 square foot garage than the square math suggests. Ask about it up front rather than being surprised.
Superior works across Portland and greater Cumberland and York Counties, and the rolled asphalt page covers installation, replacement, and repair. Estimates are free, and measuring your slope first costs nothing either way.
Frequently Asked Questions
What is rolled asphalt roofing?
Rolled asphalt roofing is mineral-surfaced asphalt sheeting sold in rolls and installed on low slope roofs. It uses the same asphalt and granule construction as shingles but comes as a continuous sheet rather than cut tabs, which makes it faster and cheaper to install on sheds, garages, and porch roofs.
What is the minimum slope for rolled asphalt roofing?
Mineral-surfaced roll roofing cannot be applied on roof slopes below 1 unit vertical in 12 units horizontal, an 8 percent slope, under the 2021 International Residential Code. Individual manufacturers may specify a steeper minimum than the code floor, so check the product data sheet as well as the code.
How much does rolled asphalt roofing cost in Portland, Maine?
National figures put installed rolled roofing at roughly $2.00 to $5.50 per square foot, which is about half the cost of rubber or architectural shingles. Maine specific pricing is not collected separately, so treat published ranges as a check against a quote rather than as a quote.
How long does rolled asphalt roofing last in Maine?
Standard mineral-surfaced roll roofing lasts about 5 to 10 years, while modified bitumen and torch-down products in the same family reach 10 to 20 years. Maine’s freeze-thaw cycling pushes results toward the lower end of either range, and fastening method changes the outcome as well.
Is rolled asphalt roofing cheaper than shingles?
Yes, per square foot, at roughly half the installed cost. Measured per year of service life the picture reverses, because rolled asphalt lasts a fraction as long. On a structure you plan to keep for decades, shingles or a membrane usually cost less over time.
Rolled asphalt or EPDM rubber for a low slope roof?
Rolled asphalt costs less up front and lasts 5 to 10 years. EPDM rubber costs more and lasts 20 to 30 years with far fewer seams. Choose rolled asphalt for unheated outbuildings and EPDM where heated living space sits underneath.
Can rolled roofing go over existing shingles?
Sometimes, if the existing surface is smooth, sound, and dry. It is often a poor idea. The old surface telegraphs through the new one, the added weight loads the structure, and covering the deck means nobody inspects it until the next failure. On a low slope roof, deck condition is what you most want to see.
Is rolled asphalt roofing good for a shed or detached garage?
Yes. Unheated outbuildings are the strongest use case. Nothing heated sits below the roof, so a leak is an inconvenience rather than a structural and mold problem, and the short service life matches how these structures are typically maintained.
Can I put rolled asphalt roofing on my house?
It is a poor choice for a main house roof. The short service life means replacing it repeatedly within the span of one shingle roof, and it reads as deferred maintenance in a home inspection report when you sell. Slope permitting, shingles or metal serve a primary residence better.
Does Maine require an ice barrier under rolled roofing?
Yes, where there is a history of ice forming along the eaves and backing water up, an ice barrier is required for mineral-surfaced roll roofing. Coastal Maine qualifies. A quote that omits the ice barrier is incomplete rather than competitive.
What does a rolled roofing warranty cover?
Manufacturer warranties on roll roofing cover manufacturing defects, not service life, and claim windows can be as short as five years from installation. Installation quality is covered separately by the contractor’s workmanship warranty. Ask for both documents in writing before work begins.
Sources
- International Code Council, 2021 International Residential Code, Chapter 9, Section R905, Requirements for Roof Coverings. Accessed August 2026.
- HomeGuide, Roll Roofing Cost Guide. National cost aggregator. Accessed August 2026.
- Reroofing Guidelines per the 2021 International Codes, municipal building department publication. Accessed August 2026.
- Superior Roofing, What Roof Replacement Costs in Portland, Maine, 2026 pricing guide. Accessed August 2026.
- Maine Office of the State Fire Marshal, Building Codes, Maine Uniform Building and Energy Code. Accessed August 2026.
- Maine Department of Energy Resources, Building and Energy Codes. Accessed August 2026.
- New England Metal Roof, Roll Roofing Life Expectancy and How to Maximize Its Lifespan. Regional contractor resource. Accessed August 2026.
- GAF, Mineral Guard and RainCap Residential Roll Roofing Limited Warranty Against Manufacturing Defects. Accessed August 2026.
- GAF, Mineral Guard Residential Roll Roofing product specification. Accessed August 2026.
- Fixr, What Is Roll Roofing, and How Do You Install It, reviewed by John A. D’Annunzio, roofing and waterproofing consultant. Accessed August 2026.
- D and G, Rolled Roofing: Cost, Installation, and Pros vs Cons. National guide. Accessed August 2026.