How Long Is a Roll of Rolled Roofing Lengths and Measurements
Rolled roofing is a budget-friendly option for sheds, porches, and low-slope roofs. Understanding the typical lengths and how to estimate material needs helps prevent shortages or waste. This guide reviews common roll dimensions, how lengths affect installation, and practical tips to measure, purchase, and cut rolled roofing efficiently.
What Is Rolled Roofing
Rolled roofing is a asphalt-saturated fabric or mineral-surfaced mat that comes in long, narrow rolls. It is designed for lightweight, low-slope applications and is known for quick installation and easy handling. Rolls are sold by width and length, with the most common width being 36 inches. Lengths can vary, and knowing these dimensions helps calculate how many rolls are needed for a project.
Typical Roll Lengths And Widths
The standard rolled roofing size in the United States is about 36 inches wide. Lengths most often sold are:
- 12 feet (144 inches)
- 20 feet (240 inches)
- 30 feet (360 inches)
- 40 feet (480 inches) in some industrial or specialty cases
Some manufacturers offer shorter or longer bundles, but 12-foot and 20-foot rolls are the most common for residential DIY use. When shopping, verify the exact length printed on the roll’s packaging, as slight variations can occur between brands.
Factors Affecting Roll Length
Several factors influence the length you’ll need for a project:
- Roof area: Measure square footage and convert to needed rolls based on roll width.
- Pitch and overlap: Low-slope roofs may require more material due to overlaps at seams.
- Waste factor: Cuts around chimneys, vents, and edges create waste. A typical waste allowance is 5–10% for irregular shapes and wasteful cuts.
- Roll availability: Some local suppliers stock only certain lengths; plan ahead to avoid mismatches.
- Adhesive and fasteners: Some installations require additional starter strips or cap materials that influence how many rolls are practical for the project.
Calculating Material Needs
To estimate how many rolls you need, follow these steps:
- Measure the roof’s total area in square feet. For example, a 20 ft by 24 ft roof equals 480 square feet.
- Convert the width to feet. A 36-inch roll is 3 feet wide.
- Compute the length of rolls needed by dividing the area by the roll width: 480 sq ft ÷ 3 ft = 160 linear feet of roll needed.
- Determine how many 12-foot rolls are required: 160 ft ÷ 12 ft per roll ≈ 13.3 rolls, so purchase 14 rolls.
- Apply a waste factor (e.g., 5–10%) for irregular cuts: 14 rolls × 1.05 ≈ 15 rolls.
For sloped roofs with multiple planes, calculate each plane’s area separately and sum the results, then apply the waste factor. If access or storage challenges exist, consider purchasing a few extra rolls to accommodate unplanned cuts.
Installation Considerations For Roll Lengths
Length differences impact handling and installation speed:
- Long rolls reduce the number of joints but require more space to unroll and align. On tight job sites, shorter rolls may be easier to maneuver.
- Shorter rolls can simplify cutting around features and facilitate waste management on the ground.
- Aligning the roll direction with the roof’s rafter lines helps ensure fasteners and seam placements are consistent.
- Ensure the surface is clean, dry, and free of debris to prevent roll slippage during installation.
Measuring And Purchasing Tips
These practical tips help ensure accuracy and minimize waste when buying rolled roofing:
- Always measure twice: length and width of the roof area, then recalculate to count full rolls rather than scraps.
- Check product specifications: confirm roll width (usually 36 inches) and length (commonly 12 or 20 feet).
- Consider curb-to-edge layouts: for irregular roof shapes, map out seams to reduce costly offcuts.
- Factor in overhangs: extended edge coverage may require additional material beyond the main roof area.
- Ask suppliers for cut-to-length options if available, especially for large projects with precise measurements.
Handling And Storage Of Rolled Roofing Lengths
Proper handling preserves roll quality and minimizes damage:
- Store rolls on a flat, dry surface to prevent creasing and moisture exposure.
- Avoid stacking heavy rolls on top of one another where possible to prevent deformation.
- Keep rolls away from direct sunlight to prevent premature aging of the asphalt coating.
- Transport rolls off the ground on a dolly or pallet to reduce wear on the edges.
Common Pitfalls And How To Avoid Them
Awareness of typical mistakes helps ensure a smooth installation:
- Underestimating waste: irregular roof shapes often require a higher waste factor than anticipated.
- Ignoring roof pitch: steeper roofs may affect roll handling and the number of rolls used for overlaps.
- Failing to verify local code requirements: some jurisdictions have specific requirements for rolled roofing materials on certain structures.
- Not checking for warranty conditions: some warranties require precise installation methods that reference roll lengths and overlaps.
Practical Example: Small Garden Shed Roof
A 12 ft by 14 ft garden shed roof has an area of 168 square feet. With a 3-foot-wide roll, the area per linear foot is 3 sq ft. You need 56 linear feet of roll (168 ÷ 3). Using 12-foot rolls, you’d require 5 rolls (60 ft total). Add a 10% waste factor for cuts and overlaps, resulting in about 6 rolls. This example illustrates how even small projects benefit from precise measurements and a little extra for adjustments.
Choosing The Right Roll For Your Project
Most residential projects use standard 36-inch-wide rolls in 12- to 20-foot lengths. For larger or uneven roofs, multiple lengths and careful layout plans help minimize waste. When accurate measurements and proper calculation are followed, rolled roofing can provide a durable, economical option for low-slope roofing needs.