Roll Roofing: What It Is, How It Works, and Rolled Roofing vs Shingles

Roll roofing is one of the most affordable and fastest-installing roofing materials for low-slope and flat roof surfaces. Unlike shingles that install as individual pieces, roll material comes in 36-inch wide, 33-foot rolls that cover 100 square feet per roll with standard overlap. Understanding what is roofing with rolled materials — and when it is the right choice — helps you make informed decisions for sheds, garages, porches, and cabin roofs.

This guide covers what is rolled roofing and its applications, how rolled roofing vs shingles compares on performance and cost, and whether does roll roofing need underlayment for your specific installation.

What Is Roll Roofing and How Is It Used

Common roll roofing applications

Roll roofing is a mineral-surfaced asphalt product that shares the same basic construction as asphalt shingles — a fiberglass or organic mat saturated with asphalt and coated with mineral granules. The difference is format: instead of individual tabs, the material comes as a continuous roll. It is best suited for roofs with a pitch between 1:12 and 2:12 (very low slope), where standard shingles would leak due to inadequate drainage head.

Typical applications include: utility sheds, detached garages, porch roofs, farm buildings, and low-slope dormer extensions. It is not the first choice for primary residence roofs where longevity and aesthetics matter, but it is the practical, economical solution for structures where budget and installation speed are priorities.

Roll roofing materials overview

The most common type is 90-pound mineral-surfaced roll roofing, named for its weight per 100 square feet. Smooth-surfaced cap sheet (without mineral granules) is used as base layers in built-up roofing systems. Cold-process modified bitumen roll products offer enhanced flexibility and longevity over standard asphalt roll material and can be applied with adhesive rather than heat, making them a safer DIY option on structures where propane torch work is risky.

Rolled Roofing vs Shingles: Key Differences

When comparing rolled roofing vs shingles, the key differences are cost, lifespan, and slope requirements. Roll roofing material costs $30 to $60 per square (100 sq ft), while architectural shingles run $100 to $200 per square. Installation is faster with rolls — a single-story shed roof takes a couple of hours. Shingles install more slowly but deliver 25 to 30 years of service life. Roll roofing typically lasts 10 to 15 years before granule loss and cracking require replacement.

Aesthetically, shingles provide a more finished, residential appearance with shadow lines and color variation. Roll roofing presents a flat, uniform surface that is acceptable for outbuildings but undersells the look of a residence. For a primary home with any visible roof pitch, architectural shingles are the standard choice. For secondary structures on a tight budget, roll roofing delivers functional waterproofing at the lowest material and labor cost.

Does Roll Roofing Need Underlayment?

Whether does roll roofing need underlayment depends on the installation method and roof pitch. On slopes of 2:12 or greater, standard installation calls for a layer of roofing felt (15-pound or 30-pound) over the deck before roll roofing application. This provides a secondary water barrier and smooths out minor deck irregularities.

On pitches of 1:12 to 2:12, the recommended practice is a double-coverage installation method — half the roll width is lapped by the course above, providing two layers of material at every point on the roof. In this method, the underlayment IS the first half-width run of roll roofing. The deck must be clean, flat, and free of protruding nail heads before any installation begins.

Installing Roll Roofing Step by Step

Basic installation on a low-slope surface:

1. Clean and inspect the deck — replace any soft or damaged sheathing
2. Install drip edge along the eaves and rakes
3. Begin at the lowest edge, unrolling the first course and allowing 1/4 inch overhang past the drip edge
4. Nail every 3 inches along the edges and every 12 inches through the field using roofing nails with large heads
5. Apply roofing cement under each seam before pressing the next course down, overlapping at least 6 inches for slopes 2:12 and above, or 50 percent for double-coverage on lower slopes
6. Seal all exposed nail heads and seam edges with roofing cement

Next steps: Verify your roof pitch before purchasing materials — if your pitch is steeper than 2:12, architectural shingles will outperform and outlast roll roofing significantly. For pitches at or below 2:12, roll roofing is the right call. Consider modified bitumen alternatives for any roof where you expect 15 or more years of service life from your investment.