Roll Roofing: What It Is, Pros, Cons, Installation & More

By Jack Gray, Roof Online Editor • Published August 21, 2024

Introduction

There’s an old joke that contractors like to tell: “Good, fast, cheap — you can only pick two!” This is one of those jokes that contains much wisdom and actually expresses a deep, abiding truth about the world. I even saw it on a bumper sticker once. When I see a roof with roll roofing on it, I know which two they picked…fast and cheap.

Roll roofing is typically used (and only recommended for) roofs that need something put on them quick to keep the rain out, but you don’t want to spend too much money doing it. This situation is usually because of some kind of recent roof damage that needs a temporary fix or because you can’t afford to install a better-performing, more permanent type of roof at the moment. Situations where roll roofing may actually be a preferred choice would be on the less critical roofs on structures like sheds, barns, or carports, where the performance of the roofing material isn’t so important, and doing a cheap re-roofing job every 10 or 15 years is not a big deal.

What is roll roofing?

“Roll roofing” is the common term used for either smooth-surfaced or mineral-surfaced asphalt-coated roofing felts when they are used as a primary roof covering. You might see some people calling it “rolled roofing”, but that isn’t what most knowledgeable roofing professionals call it. Mineral-surfaced roll roofing (or “MSR”, for “mineral surfaced roofing”) is by far the most common type. People do actually call the mineral surfaced variety “MSR” sometimes, but nobody calls smooth surfaced roll roofing “SSR”, because that would make people think you were talking about standing seam (metal) roofing.

Roll roofing is basically a giant piece of what would be a cheap asphalt shingle if it were a lot smaller. It’s made pretty much the same way as shingles are, but it’s produced in three-foot wide rolls about 33 to 36 feet long instead of being cut up into individual shingles. The rolls are almost always designed to cover one roofing square (100 square feet) when installed, so variations in product dimensions are usually on account of the manufacturers having different installation guidelines regarding the amount that one roll should overlap another when they are installed.

Like asphalt shingles, roll roofing is composed of an asphalt-saturated reinforcement mat coated with layers of asphalt on both sides and topped off with a layer of protective mineral granules on the top surface. Unlike high-end asphalt shingles, the asphalt used in roll roofing is not modified with the addition of rubber or plastic polymers to improve resilience or performance in extreme temperatures. If it was modified like this, then it would be modified bitumen roofing, which is its own distinct type of roofing.

Unlike modified bitumen roofing, which the building code allows to be installed on roofs with slopes down to ¼-in-12, roll roofing may not be installed on roofs that have a slope of less than 1-in-12. Also, when you see what looks like roll roofing on a commercial low-slope roof on an office building or a hotel, it’s almost 100% guaranteed to actually be a modified bitumen roof installed with two or three plies (membrane layers).

History of Roll Roofing

Roll roofing dates back to the mid-to-late 1800s, when commercial applications for asphalt-based roofing products were first being explored. When oil refining became big business, and kerosene and gasoline and heating oil sales took off, there was suddenly a lot of leftover asphalt as a result. People began looking for ways to use it. Although it wasn’t as good of a low-slope roofing material as coal tar pitch, asphalt-based built-up roofs began to be installed. As a component of built-up roofing, asphalt-saturated and asphalt-coated felts were produced. It wasn’t much of a leap to give these felts an extra coating of asphalt and a protective surface, and simply start using them as a cheap roofing material in their own right.

This technique only became possible with the increase in asphalt availability as a byproduct of the oil business; the main material used in low-slope roofing at that time was coal tar pitch, and coal tar pitch does not perform well on slopes greater than ½-in-12. Unlike asphalt, coal tar pitch always remains slightly fluid, and if it’s installed on steeper roofs it will tend to slowly slide or drip down the roof.

Roll roofing was originally manufactured using organic felts made out of cellulose derived from raw materials like wood chips or old rags and paper. In the second half of the 20th century, in an effort to find a cheaper substitute for organic felts, manufacturers developed reinforcement mats made out of fiberglass or polyester, which turned out to perform better, having greater moisture resistance and dimensional stability compared to the cellulose-based felts. Some people do still swear by organic felts, though, which actually perform better than fiberglass in very cold weather. An interesting thing is that asphalt shingle manufacturers stopped producing shingles with organic mats around 2010, but you can still buy roll roofing than uses organic felts.

Why People Use Roll Roofing

Roll roofing is relatively very easy to work with. It doesn’t take a lot of skill or experience to install a functional roof using it. Unlike shingles and tiles or single-ply systems, roll roofing can generally be applied quickly with a hammer and nails, chalk line, tape measure, roof cement, and a trowel for applying the roof cement. This makes it a fairly popular choice for DIY roofing projects on sheds, garages, and other smaller structures where roof performance failures aren’t likely to cause catastrophic interior damage. Higher-quality roll roofing may also be used by professional roofers on small low-pitched roofs (over porches, for instance) for which shingles may not be suitable.

The main reason people use roll roofing is the price. It’s basically the cheapest roofing material you can get. It typically costs less than half of what the same coverage in asphalt shingles costs, and asphalt shingles are themselves some of the cheapest roofing materials. You can compare the prices for yourself on the Home Depot website: roll roofing at Home Depot vs. asphalt shingle at Home Depot. (Note that a roll of roll roofing typically covers the same amount of roof area as three bundles of shingles.)

Pros of Roll Roofing

Cost-Effective: Roll roofing is one of the most affordable roofing options available. It is cheaper than most other roofing materials such as asphalt shingles, metal roofing, or tile.
Ease of Installation: Roll roofing is relatively easy to install, especially compared to more complex systems like built-up roofing (BUR) or asphalt shingles. It requires fewer tools, less labor, and can be applied quickly by even semi-skilled workers.
Speed of Installation: Due to its large rolls, roll roofing can cover large areas in a short time. This makes it a great option for projects where time is a significant factor, such as emergency repairs or covering sheds and garages.
Suitable for Low-Slope Roofs: Roll roofing is well-suited for low-slope roofs (with a slope of 1:12 or greater). It provides coverage that sheds water effectively on less steep pitches.
Multiple Installation Methods: Roll roofing offers flexibility in installation. Techniques like the concealed nail method, exposed nail method, and double coverage method give options for different roof types and requirements.
Lightweight: Roll roofing is lighter than many traditional roofing materials. This reduces the load on the roof structure, making it a viable option for older buildings or smaller structures like sheds and garages.
Good for Small Structures: Roll roofing is an excellent choice for small buildings like sheds, workshops, barns, and garages, where aesthetics and longevity are less critical than weatherproofing and affordability.
Mineral Granule Protection: The addition of mineral granules to the surface of roll roofing helps protect it from UV rays and increases its fire resistance, thereby extending its lifespan in moderate conditions.
Minimal Seams: Since roll roofing comes in large rolls, there are fewer seams compared to other roofing systems like shingles, reducing the number of potential leak points.
Adaptability for Repairs: Roll roofing can be easily used for patch repairs on various types of roofing systems. Its simplicity allows for quick emergency fixes.
Light Maintenance Requirements: Roll roofing typically requires little maintenance, making it a good choice for secondary buildings or temporary solutions.

Cons of Roll Roofing

Shorter Lifespan: Roll roofing generally has a shorter lifespan compared to materials like asphalt shingles, metal roofing, or tile. It typically lasts around 5 to 10 years, depending on the installation quality and weather conditions.
Not Suitable for Steep Roofs: Roll roofing is not recommended for steep-slope roofs (greater than a 2:12 pitch) because it lacks the structural integrity of materials designed for these applications.
Less Durable: Roll roofing is thinner and less durable than other roofing options, making it more susceptible to damage from environmental factors such as high winds, hail, and extreme temperatures.
Vulnerability to Weathering: Although the mineral granules provide some protection, roll roofing is still more prone to weathering, especially in harsh climates where UV rays, snow, ice, or wind are constant factors.
Aesthetic Limitations: Roll roofing lacks the aesthetic appeal of other roofing materials like shingles, tiles, or metal. It is typically considered less attractive, making it less suitable for residential homes where appearance is a priority.
Waterproofing Challenges: Proper installation is crucial for roll roofing to remain waterproof. If overlaps, seams, or edges are not correctly sealed, leaks can develop, particularly on low-pitch roofs where water drains slowly.
Limited Color Options: While roll roofing may come with mineral granules in different colors, the color selection is still limited compared to other roofing materials like asphalt shingles, which offer a wide range of styles and shades.
Prone to Buckling and Wrinkling: If not properly installed or if the material is laid out in cold temperatures, roll roofing can buckle or wrinkle over time, creating weak spots where water can infiltrate.
Not Ideal for Permanent Structures: Roll roofing is typically used as a temporary or secondary solution, not intended for long-term use on permanent structures like homes.
Requires Specific Conditions for Installation: Roll roofing must be installed in warm weather for best results. Cold or wet conditions can cause problems with adhesion and flexibility, leading to issues during and after installation.
Susceptible to Tearing and Puncturing: Due to its thinner nature, roll roofing is more easily torn or punctured by sharp objects, debris, or even improper handling during installation.
Less Effective at Handling Extreme Snow Loads: Roll roofing lacks the strength to handle extreme snow loads in colder climates, which can lead to sagging or failure over time if not adequately reinforced.
Seams and Edges Can Deteriorate: Over time, the seams and edges of roll roofing can deteriorate, especially if exposed to constant wind or freeze-thaw cycles, making it more prone to leaks.
Susceptible to Wind Uplift: Roll roofing can be vulnerable to wind uplift, especially if it is not properly adhered or nailed. This can lead to sections being torn off in strong winds.
Requires Regular Monitoring and Maintenance: Although maintenance is generally light, roll roofing requires more frequent monitoring compared to more durable roofing systems, especially in areas prone to severe weather.
Challenges in Re-Roofing: If roll roofing needs to be replaced or re-roofed, the old material often must be completely removed, as it is difficult to layer new material over old roll roofing without causing issues such as trapping moisture or reducing the roof’s integrity.

How to Tell Roll Roofing and Modified Bitumen Apart

It can be difficult to tell the difference between roll roofing and modified bitumen roofing simply by looking at it, but this should help:

Material Characteristics:
- Roll Roofing is a low-quality, asphalt-based product often used for temporary roofing. It is less flexible, and you can typically tear a corner off of it by hand. Roll roofing is commonly 36 inches wide and has a life expectancy of about 5-10 years.
- Modified Bitumen Roofing is a higher quality, polymer-modified asphalt product that is tougher and more flexible than roll roofing. Modified bitumen is usually 39 inches wide and has a longer life expectancy. If you try to tear off a corner on a piece of modified bitumen, you probably will have a very hard time doing it, if you can at all. The asphalt in modified bitumen is stronger and more resilient due to the modification polymers, and modified bitumen sheets usually have a strong polyester reinforcement mat, whereas roll roofing will almost always have a weaker cellulose or fiberglass mat.
Installation Methods:
- Roll Roofing is typically nailed in place with exposed nails, often covered with roofing cement. It may also be used as a flashing material. In lower-sloped applications, the performance of roll roofing is reduced, often lasting only around five years.
- Modified Bitumen Roofing is installed using more advanced techniques, such as torching, mopping, or peel-and-stick methods. The seams of modified bitumen are often torched or mopped together with hot asphalt, and this roofing type may feature granule surfaces for additional UV protection.
Seams and Flashings:
- Roll Roofing often features visible nails and will usually have roof cement along the seams/laps. It is not commonly used for flashings.
- Modified Bitumen Roofing tends to have seams approximately every 3 feet with a bleed-out of asphalt at the seams. The same material is usually used for flashing, giving the entire roof a more uniform appearance.
Durability and Application:
- Roll Roofing is often used in temporary applications or on smaller structures like sheds or garages. It is more prone to cracking, blistering, and buckling.
- Modified Bitumen Roofing is more resistant to weathering, mechanical damage, and UV exposure. It is typically used on higher-quality installations and can last up to 20 years with proper maintenance.

A quick visual clue to differentiate them is to check the width of the rolls (roll roofing is usually 36 inches, and modified bitumen is 39 inches) and examine the flexibility of a small piece of the material. Roll roofing is more brittle and breaks easily, while modified bitumen bends without breaking. If you fold a small piece of the roofing in half, the roll roofing will likely crack, and the mod bit won’t.

Manufacturing of Roll Roofing

Roll roofing is manufactured using a process similar to that of asphalt roof shingles. The material begins with a felt base, which can be organic (such as wood fibers, paper, or sawdust) or inorganic (such as fiberglass or polyester). The felt is saturated with asphalt or coal tar to waterproof it. After saturation, the felt is coated with asphalt, which may be protected with mineral granules (for mineral-surfaced roofing). The purpose of the granules is to protect the asphalt from UV rays, enhance fire resistance, and add strength to the material. The rolls are manufactured in a variety of weights and widths, and both organic and fiberglass bases are available.

Materials Used in Roll Roofing

Asphalt

Asphalt is the key waterproofing agent in roll roofing. Mineral stabilizers like limestone powder and silica are added to the coating asphalt to improve weather resistance and shock-proofing properties, extending the service life of the roofing material. It is applied as a saturant and coating on the roofing felts. The asphalt used in roll roofing is typically derived from refined petroleum and serves multiple purposes:

Waterproofing: Asphalt saturates the felt material, creating a moisture barrier that prevents water from seeping into the roof deck or structure.
Adhesive Properties: The asphalt acts as a binder, holding the fibers in the felt together and helping to attach the roofing material to the substrate. It also aids in bonding overlapping sections of roll roofing, ensuring a tight seal.
Weather Resistance: Asphalt provides resilience against weathering by protecting the roof from rain, snow, and extreme temperatures. When combined with mineral granules, it offers further UV protection, which prevents the asphalt from breaking down due to prolonged sun exposure.
Flexibility: Asphalt allows the roofing material to remain flexible, even in low temperatures, which helps reduce the risk of cracking or splitting under stress.

The quality of the asphalt used in roll roofing can vary, influencing the overall performance of the product. High-quality asphalt typically contains additives that improve its longevity, reduce brittleness, and increase its resistance to aging and wear

Felts/Reinforcement Mat

Organic Felts:

The materials used in roll roofing include organic felts (wood fiber, paper, sawdust) and fiberglass or polyester. Organic felts tend to absorb moisture, which causes swelling and shrinking.

Inorganic Felts:

Fiberglass and polyester are the two main inorganic felts, offering better moisture resistance and strength. Fiberglass is especially valued for its dimensional stability, while polyester offers high resistance to puncture and tearing.

Fiberglass offers significant advantages over organic materials due to its superior moisture resistance and dimensional stability. Unlike organic felts, which tend to absorb water and are prone to swelling and shrinking, fiberglass remains stable under different weather conditions. This stability helps prevent issues like buckling or warping of the roofing material, making fiberglass a preferred choice for longer-lasting and more durable roll roofing applications.

Mineral Granules

Toward the end of the manufacturing process, ceramic-coated mineral granules are applied to the weathering surface (the top) of roll roofing. These granules come in a (limited) variety of colors so the consumer can pick a roof color he likes.

The mineral granules on roll roofing serve primarily to protect the underlying asphalt from UV rays and weathering. These granules are embedded in the surface of the roofing material and play a role in enhancing its durability, strength, and fire resistance. Additionally, they contribute to the overall aesthetics of the roofing by offering color variations.

The granules also help prolong the service life of the roofing material by providing a protective barrier that reduces wear and tear caused by exposure to the elements.

Installation Techniques

Please remember that no matter what you read here or anywhere else about roll roofing installation, you should always follow the manufacturer’s installation instructions. Failure to follow the manufacturer’s recommendations and guidelines may void your product warranty and may even violate building codes, which often state that roofing materials “shall be installed in accordance with this chapter and the manufacturer’s instructions“.

You should never try to torch down regular roll roofing. The material is not designed for that and you’ll ruin it and probably set your shed on fire.

Concealed Nail Method

The concealed nail method for installing roll roofing is a technique that prioritizes protection against water infiltration, particularly on low-slope roofs where water drainage is slower. Here’s a detailed explanation of the method:

Preparation: The concealed nail method is specifically recommended for slopes with a 1:12 pitch or less, where exposed nails could allow water to seep in due to the slow runoff. This method involves hiding the nails under layers of roofing material to prevent exposure to the elements.
Installation Steps:
- Start by snapping a chalkline across the roof approximately 35 1/2 inches from the eave to position the first strip of roll roofing.
- Nail only the top edge of the strip, placing nails about 3/4 inches from the edge and every 4 inches along the top. The edges of the strip along the rakes and eaves should be coated with roofing cement, but not nailed, to prevent exposure to water.
- Overlaps between strips should be at least 6 inches. The lower layer is nailed down, coated with roofing cement, and then the top layer is pressed into the cement. This ensures a watertight seal.
Layering and Continuation: Continue up the roof by positioning subsequent strips of roll roofing 4 inches below the upper edge of the previous strip. Nail along the top edge and use roofing cement along the overlap to create a strong bond. When approaching the top edge of the roof, the ridge should be covered with metal drip edging, secured with nails spaced every 6 inches.
Key Considerations:
- This method works best on shed roofs or similar low-pitch applications without hips or ridges.
- Special attention is needed to avoid cracking or improperly securing the roofing material, particularly in valleys where water is most likely to collect.

This method provides superior protection in areas where water runoff is a concern, offering better durability than exposed nail methods.

Exposed Nail Method

The exposed nail method for installing roll roofing is a more straightforward technique compared to the concealed nail method. Here are the key details of the process:

Positioning and Initial Fastening: To begin the exposed nail method, the roofer positions the first roll of roofing material along the eave, aligning it with a chalk line snapped 35 1/2 inches up from the eaves. Nails are placed along the top edge, spaced every two feet and positioned 3/4 inches from the edge. The rake and eave edges are then secured with nails placed 3/4 inches from the edge and spaced three inches apart.
Overlapping Rolls: If a single sheet of roll roofing does not cover the entire roof width, the next roll is overlapped by six inches. The first sheet is nailed down, then coated with roofing cement, and the overlap is secured in place. This ensures that the overlap creates a waterproof seam.
Subsequent Layers: For the subsequent layers, a chalk line is snapped two inches below the top edge of the previous course. The upper edge of the next strip is tacked in place, and a two-inch-wide layer of roofing cement is spread along the top edge of the first strip. The second course is then nailed over the cement, following the chalk line for alignment. Joints between courses must be staggered to prevent them from aligning directly above one another.
Special Considerations: This method is typically used on low-slope roofs where water runoff is slow. The method is faster than concealed nailing but leaves the nails exposed to the elements, which can reduce the durability of the roofing system. Proper care must be taken to ensure that the nails are securely driven and properly placed.
Hips and Ridges: For hips and ridges, a strip of roll roofing six inches wide is cut and bent to fit over the joint. The strip is nailed in place, and any end-laps are overlapped by six inches and coated with roofing cement.

In summary, the exposed nail method is simpler and faster but can be less durable due to the exposure of nails to weather. It is commonly used in certain applications where the roof slope or other conditions allow for this faster installation method.

Double Coverage Method

The double coverage method is considered the most durable of the three primary roll roofing methods. Here are the key details:

Material: Double-coverage roll roofing typically uses a roll roofing sheet that is 36 inches wide. Of this width, 19 inches is reserved for the selvage edge (overlap), and 17 inches is intended for exposure. Different manufacturers finish the selvage portion in various ways, such as saturating or coating it. This roofing can be applied with either hot or cold asphalt adhesives, depending on the manufacturer’s specifications.
Installation Process:
- Start by snapping a chalk line across the roof about 35 1/2 inches from the eave.
- The first strip of roofing material is positioned along this line. It is nailed along the top edge, leaving the bottom section of the sheet unsecured for now.
- The selvage edge of the roofing strip (19 inches) is folded back while an adhesive (cold or hot asphalt) is applied to the exposed portion of the roof. The roofing is then pressed into the adhesive and securely rubbed down.
- Nails are spaced approximately 12 inches apart along the top edge of each strip.
- Each subsequent layer is overlapped by 19 inches to ensure double coverage, which is why one roll of material covers only half of the standard square footage.
Advantages:
- This method provides excellent protection due to its double-layer system, which is particularly suitable for low-pitch roofs with a minimum slope of 1 in 12.
- It can extend the lifespan of the roof by offering better protection against water infiltration.
Adhesive Application: The adhesive is brushed on with care to ensure that it reaches the lap line between layers of material. This helps to seal the roof thoroughly and prevents water from penetrating the overlaps.
Important Considerations:
- Roll roofing, including double-coverage applications, should not be installed in cold weather. In cold climates, the material may not adhere properly. If needed, allow the material to warm up in the sun before proceeding with installation.
- The roofing material must be installed in a way that avoids exposed nails, as they can lead to leaks over time.

The double-coverage method is particularly valued for its durability and is frequently chosen for low-pitched roofs.

Special Applications and Repairs

Roll roofing is ideal for specific applications such as valley coverage and minor repairs. For valleys, double layers of roll roofing or metal strips can be used. Proper application is essential to prevent issues like premature wear or leaks.

Valley Coverage:

Valleys are the areas where two roof surfaces meet and channel water, making them especially prone to wear and leaks. Roll roofing is commonly used to provide additional protection in valleys because of its seamless installation.
Installation: When using roll roofing in a valley, it’s essential to apply at least two layers of material to reinforce the area. The first layer should be cut to fit the valley and secured in place with roofing nails. The second layer should overlap the first by about six inches and should be adhered with roofing cement to create a watertight seal.
Metal Strips: In some applications, metal strips (typically galvanized steel or aluminum) are also used in the valley before laying the roll roofing. These metal strips provide an added layer of protection by helping water flow smoothly down the valley and off the roof without penetrating the roofing material.

Repairs:

Repairing Leaks: Roll roofing is often used for spot repairs on existing roofs, particularly for addressing leaks. When repairing a roof leak, first identify the source of the leak. If a portion of the roll roofing has torn or deteriorated, cut away the damaged section, ensuring that you extend beyond the damaged area by several inches to remove any weakened material.
Patching: Cut a new piece of roll roofing to the size of the section you’ve removed. Spread a thick layer of roofing cement on the back of the patch, then press it firmly into place over the damaged area. Apply an additional layer of roofing cement over the patch’s edges to seal it. If using nails, ensure they are placed carefully and that their heads are coated with roofing cement to prevent water penetration.

Use of Roll Roofing for Specific Structures:

Sheds and Garages: Roll roofing is commonly used on smaller, simpler structures like sheds, garages, and carports. These buildings typically have low-pitched roofs, which makes roll roofing a practical and cost-effective solution. For such applications, installation methods like the double coverage method ensure that these roofs have sufficient durability and protection against the elements.

Repairing Seams and Overlaps:

Seam Repairs: Over time, the seams between overlapping sections of roll roofing can become vulnerable due to exposure to weather, especially if the roofing cement begins to wear away. To repair a failing seam, clean the affected area thoroughly, removing any dirt or debris. Apply a generous layer of roofing cement along the seam, then press the layers back together. For additional reinforcement, you can nail along the seam before applying another layer of roofing cement over the nails and edges of the seam.

Temporary Repairs:

Emergency Fixes: Roll roofing is also useful for temporary repairs or as an emergency fix for leaks or other roof damage. In the event of a sudden leak, a piece of roll roofing can be applied quickly to the damaged area with roofing cement to provide a temporary solution until a more permanent fix can be made.

Edge Protection and Wind Uplift Prevention:

Edge Repairs: Edges of roofs, particularly along eaves and rakes, are susceptible to wind uplift and water damage. For repairs in these areas, ensure that any damaged roll roofing is removed and replaced with new material that extends beyond the roofline. Roofing cement should be applied generously under the edges to help secure the material and prevent wind from lifting it.

Durability of Roll Roofing Repairs:

Lifespan: While roll roofing is not as durable as other roofing materials like asphalt shingles or metal, it can be very effective for repairs and special applications when installed and maintained correctly. For more extensive repairs, especially on larger or more complex roofs, using roll roofing in conjunction with other materials (such as flashing or additional layers of roofing cement) can provide a robust solution.

By focusing on careful application in critical areas like valleys and edges and using proper sealing techniques, roll roofing can effectively serve both as a long-term solution for smaller buildings and as a reliable material for spot repairs and specific applications.

General Tips for Working with Roll Roofing

Installation Tips:

Roll roofing should be laid flat for 24 hours before installation to prevent wavy edges. Proper roof slope, use of correct adhesives, and application in warm weather are critical to ensure long-term performance.

Weather Conditions: Install roll roofing only in warm, dry weather. Cold temperatures can make the material brittle and hard to work with, leading to cracking or improper adhesion. Wet conditions can affect the adhesive and cause improper sealing. Always check the weather forecast and plan the installation for a period of clear, warm days.
Proper Slope: Ensure that the roof slope is appropriate for the method of roll roofing installation. Roll roofing works best on slopes of at least 1:12 for double coverage, while the concealed nail method is ideal for low-slope applications. Avoid using roll roofing on completely flat roofs, as the material is not designed to handle standing water.
Avoid Exposed Nails: Exposed nails are a common cause of leaks in roll roofing, particularly in low-slope applications where water runoff is slower. Always strive to use installation methods that conceal nails under the roofing material, such as the concealed nail method. In this approach, nails are driven into the top edge of each roll and hidden beneath the overlap of the next layer. This not only protects the nails from direct exposure to the elements but also ensures a more durable, watertight roof. If exposed nails are unavoidable, such as along rakes or eaves, coat the nail heads with roofing cement to create a waterproof seal and prevent water penetration over time. Avoid overdriving nails, as this can compromise the integrity of the material and lead to leaks.
Edge Sealing: Pay special attention to the edges of the roof, particularly along the eaves and rakes. Apply roofing cement under the edges to create a better seal, helping to prevent wind uplift and water infiltration.
Material Preparation: Allow roll roofing materials to relax by unrolling and laying them flat for 24 hours prior to installation. This helps prevent rippling, curling, or waves in the material, ensuring a smoother application.
Overlap Consistency: Ensure that overlaps are consistent across the entire roof to avoid weak spots. The standard overlap for single-coverage installation is around 4 to 6 inches, while double coverage often requires an overlap of 19 inches. Maintain these measurements for uniform protection.
Nail Placement: For the best results, nail placement should follow manufacturer guidelines. Nails should be placed 1 inch from the edges and spaced approximately 6 to 12 inches apart. Avoid overdriving the nails, as this can puncture the roofing material and cause leaks.
Roof Ventilation: Proper roof ventilation is critical to preventing moisture buildup under the roofing material, which can lead to condensation and subsequent damage. Make sure that there is adequate airflow through the attic or roof space.
Use of Flashing: Be sure to install metal flashing at critical points such as chimneys, valleys, skylights, and vents. Flashing helps direct water away from these vulnerable areas, preventing leaks.

By following these additional tips and considerations, you can help ensure a longer lifespan and better performance for your roll roofing installation.