How Long Is a Roll of Rolled Roofing: Coverage, Sizes, and Uses

Rolled roofing rolls typically range from 30 to 36 feet long and cover 100 to 144 square feet per roll, depending on material type and width. This article explains common roll lengths, coverage calculations, and practical considerations to help homeowners and contractors estimate roofing needs accurately.

Roll Type	Typical Length	Width	Coverage Per Roll
Mineral-Surfaced Rolled Roofing	33.3 ft (10.16 m)	36 in (3 ft)	100 sq ft
Modified Bitumen (Torch-Down) Roll	32.8 ft (10 m)	39 in (3.25 ft)	108–112 sq ft
SBS/APP Membrane Rolls	32.8–32.9 ft (10 m)	39–40 in	110–120 sq ft

Common Rolled Roofing Roll Sizes And Why They Matter

Rolled roofing products are manufactured in standard lengths and widths to simplify installation and ordering. The most common roll length for residential mineral-surfaced rolled roofing is about 33.3 feet, while many modified bitumen and membrane rolls are supplied in roughly 32.8–33 feet lengths. Widths vary from 3 feet to 3.25 feet, which determines the square-foot coverage per roll.

Manufacturers may round dimensions differently, and special products exist in longer or narrower formats. Understanding these differences reduces waste and ensures adequate overlap during installation.

How To Calculate Coverage From A Roll

Calculating roll coverage is straightforward: multiply the roll length by its width in feet, then divide by 9 to convert square feet to roofing squares. A roofing square equals 100 square feet and is the standard unit for roofing materials.

Example: A 33.3 ft long roll at 3 ft width equals 99.9 sq ft (33.3 × 3). Round to 100 sq ft per roll. For a 32.8 ft × 3.25 ft roll: 32.8 × 3.25 = 106.6 sq ft.

Factors That Affect Practical Coverage

Nominal roll coverage differs from practical coverage due to necessary overlaps, cuts, and waste. Standard side laps (2–3 inches) and end laps (4 inches or more) reduce effective coverage by 5–10% or more, depending on roof complexity.

Complex roofs with valleys, penetrations, and dormers increase waste. Contractors typically add 10–20% to material estimates to account for waste and overlaps.

Types Of Rolled Roofing And Typical Roll Lengths

Mineral-Surfaced (Asphalt) Rolled Roofing

Mineral-surfaced rolled roofing is common for sheds, garages, and low-slope residential roofs. Typical rolls measure about 33.3 feet long and 36 inches wide, yielding roughly 100 sq ft per roll.

This product overlaps with a 2–4 inch side lap and is fastened with nails, making it economical for small flat or low-slope areas.

Modified Bitumen (SBS/APP) Rolls

Modified bitumen rolls used for flat and low-slope commercial roofing often come in 32.8–32.9 ft lengths and widths of 39–40 inches. These rolls provide 108–120 sq ft nominal coverage and are available as torch-down, self-adhering, or cold-applied sheets.

They require careful detailing at seams and penetrations and are more durable than mineral-surfaced options.

Single-Ply Membranes In Roll Form

Single-ply membranes (like EPDM in wide sheets) can be supplied in rolls, but many are supplied as large sheets that are cut to size. When in roll form, lengths often match 50–100 feet, but the practical coverage depends on job-specific widths and seaming methods.

How Roof Slope And Size Change Material Needs

Roof slope affects how much roofing material is required. Low-slope and flat roofs use rolled roofing more frequently, but steep slopes increase measured surface area slightly due to slope factor, typically adding 2–8% to material needs depending on pitch.

To calculate adjusted area, multiply the plan area by the slope factor (hypotenuse/plan run). For example, a 4/12 pitch has a slope factor of about 1.054, increasing material estimates by 5.4%.

Estimating Rolls Needed For A Project

To estimate rolls: calculate roof area in square feet; multiply by waste factor (10–20%); divide total by the nominal coverage per roll. This yields a conservative number of rolls to order and helps avoid delays from underordering.

1. Measure or obtain roof plan area in sq ft.
2. Multiply area by slope factor if pitch is greater than flat.
3. Add waste percentage (10–20%).
4. Divide by nominal roll coverage (e.g., 100 sq ft for mineral-surfaced).

Installation Considerations That Affect Roll Length Choice

Choosing the right roll size affects seams and waste. Wider rolls reduce the number of side seams but may be harder to handle and transport, while narrower rolls simplify handling at the cost of more seams and potentially more material use for overlaps.

Weather, substrate condition, and local code requirements influence the selected product. Some jurisdictions require fire-rated or reinforced membranes, which change roll specifications.

Common Mistakes When Ordering Rolled Roofing

Ordering based only on nominal roll coverage is common but risky. Failing to add adequate waste or ignoring roof complexity leads to underestimates and job delays.

Other mistakes include ignoring product limitations (temperature ranges for torch-down or adhesive curing), and not verifying local building codes or warranty conditions before purchase.

Cost Implications Of Roll Sizes And Coverage

Material cost per roll varies by product quality and brand. Mineral-surfaced rolled roofing is the most affordable per roll; modified bitumen and reinforced membranes cost more but offer longer life and better performance.

Contractors price jobs using cost per square (100 sq ft). Knowing each roll’s square-foot coverage helps compare product costs accurately rather than relying on per-roll pricing alone.

When To Use Rolled Roofing Versus Shingles Or Membranes

Rolled roofing is suitable for small low-slope areas, outbuildings, and temporary roofs. It is not recommended for primary steep-slope residential roofs where asphalt shingles or architectural roofing provide better durability and appearance.

For larger flat roofs, single-ply membranes or multi-ply built-up roofing systems usually outperform rolled roofing in longevity and leak resistance.

Practical Tips For Homeowners And Contractors

• Buy an Extra Roll: Always order at least one extra roll for repairs and unexpected waste.
• Check Product Data Sheets: Confirm exact roll dimensions and recommended overlaps from the manufacturer.
• Plan For Flashing: Account separately for flashing materials around penetrations and edges, as these are not covered by roll estimates.
• Store Properly: Keep rolls dry and stored flat to prevent curling or damage before installation.

Where To Find Reliable Product Information

Manufacturer data sheets, local building department resources, and professional roofing contractors provide the most reliable, up-to-date information. Material Safety Data Sheets (MSDS) and installation guides list exact roll lengths, widths, and recommended overlaps.

Retailers and roofing suppliers can supply product samples and clarify warranty implications tied to specific roll products and installation methods.

Key Takeaways For Estimating Rolled Roofing Needs

Most rolled roofing rolls measure approximately 32.8–33.3 feet in length and provide roughly 100–120 square feet of nominal coverage, but practical coverage is lowered by overlaps and waste. Accurate estimates require measuring roof area, applying slope and waste factors, and verifying manufacturer specifications.

Following standard calculation steps, adding a conservative waste allowance, and consulting product data sheets will ensure a smoother project with fewer surprises.