Roofs are designed to withstand an impressive onslaught of extreme weather. While they are designed for rough conditions, the daily exposure to sun, rain, hail, or snow will eventually degrade even the toughest roofs. When this happens, small leaks and penetrations can let in moisture that could result in expensive damage. In some cases, the damage could create the need for a new roof.
By avoiding the small gaps with roof sealants, you can make protecting and repairing your roof an easier and more affordable task. While some are capable of sealing small and isolated leaks, others can help create a virtually impenetrable barrier against water and sun over your entire roof. If you need to repair your roof or want to extend the life of your roof, keep reading to learn how to choose some of the best roof sealants for a variety of roofing materials.
- BEST OVERALL: Liquid Rubber Waterproof Sealant – Indoor & Outdoor
- BEST BANG FOR THE BUCK: Gorilla Waterproof Patch & Seal Tape
- BEST FOR LEAKS: Liquid Rubber Seam Tape – Peel and Stick
- BEST FOR SHINGLES: Sashco 14004 Gallon Clear Roof Sealant
- BEST FOR RV ROOFS: Liquid Rubber RV Roof Coating – Solar Reflective
- BEST FOR FLAT ROOFS: Rubberseal Liquid Rubber Waterproofing Coating
- BEST FOR METAL ROOFS: Liquid Rubber Color Waterproof Sealant
- BEST FOR FLASHING: Loctite PL S30 Black Roof and Flashing Sealant
What to Consider When Choosing the Best Roof Sealant
With so many roof sealants on the market, it can be difficult to choose the best one for your specific needs. In order to narrow down the choices, it helps to review and compare the characteristics of roof sealants. The following considerations can help take the guesswork out of determining the best roof sealant for you.
Roof sealants serve two main purposes: to protect your roof and to repair your roof. Depending on the product, roof sealants can provide a protective seal against moisture and sun exposure and can repair minor leaks before the leak creates serious damage. Although some roof sealants will be effective on virtually any type of roof, most sealants are formulated to work with specific roofing materials.
Roofing materials like asphalt shingles, composite shingles, metal, and rubber have different characteristics that require special considerations. Additionally, whether a roof is flat or slanted also can change what is considered an ideal roof sealant. Finally, whether or not you’re attempting to repair minor damage or seal an entire roof will impact the type of roof sealant that’s best.
Roof sealants can be divided into two categories: solvent-based and water-based. While solvent-based sealants are highly resilient against the elements, they are generally more expensive, thicker, and harder to apply. Water-based sealants are more affordable and emit fewer odors, but aren’t as weather resilient. They may degrade several years earlier than solvent-based sealants and, therefore, may require more frequent maintenance.
Solvent-based sealants also require the use of a respirator during application to avoid inhaling the solvent fumes, but no mask is required for water-based sealants. Disposing of solvent-based sealants also can be trickier, since they may be considered Household Hazardous Waste (HHW) and need to be disposed of at an appropriate facility. Water-based sealants can be discarded in your household trash bin after the container’s contents have fully air dried.
Within the two main categories, there are five types of roof sealants: acrylic, polyurethane, silicone, rubber, and sealant tape.
- Acrylic. The most common variety, acrylic roof sealants are specifically made to deflect ultraviolet (UV) rays. They are popular in western and southwestern states where roof sun damage can be the primary concern. Acrylic sealants also are moderately moisture resistant but don’t provide a waterproof barrier and don’t hold up well against standing pools of water, which is a common issue on flat roofs.
- Polyurethane. Polyurethane sealants are resilient against moisture but are not very resilient against UV rays. That makes polyurethane sealants preferable in areas with more rain and snow than sun.
- Silicone. Silicone sealants offer excellent protection against moisture and UV rays, which makes them suitable for any possible weather condition, including heavy rain or sun exposure. The main downside is that silicone sealants are often expensive, which can make coating a whole roof financially unfeasible for many people.
- Rubber. Rubber sealants consist of liquid rubber that acts as a powerful guard against sun and rain. These sealants are often available in thin, water-based formulas that are easy to apply. The thin nature makes it easier to seal small cracks and leaks.
- Sealant Tape. Sealant tape is made of thin strips of moisture-resistant material and is used to repair minor leaks and seal vulnerable roof seams. The tape is equipped with an adhesive backing that’s applied directly to the roofing material, making it easy to use without a messy or labor-intensive application process. Sealant tapes are also more affordable, making them better suited for repairing small sections of damaged roofing. However, they’re not designed to cover large sections of roof.
The International Organization for Standardization (ISO) established the C1 to C5 certification standards to test and rate a sealant’s ability to withstand specific environmental conditions. A sealant with a C1 certification can only tolerate environments with minimal corrosive elements, like heated buildings with clean atmospheres. A sealant with a C5 certification can tolerate highly corrosive environments, like buildings with high levels of condensation or humidity and high pollut
The C5 rating can be further divided into C5I for industrial settings, like factories with high humidity and pollution. And C5M for marine settings like boats and docks exposed to high levels of moisture and salt. Most residential roof sealants won’t have a corrosive resistance rating as high as C5M, but you may want to explore C5M certified sealant options if your roof is exposed to particularly corrosive conditions.
Every type of roof sealant will offer some protection against water, but not all are capable of producing a completely waterproof membrane. If your main goal is to waterproof your roof, the best sealant types are rubber, silicone, and polyurethane. Each one of these can tolerate heavy rain and pooling water that acrylic sealants and sealant tapes can’t handle as well.
Regardless of the type of sealant used, multiple coats are often required to create a completely waterproof seal over your entire roof. If that’s your intended purpose, it’s important to follow the manufacturer’s directions for creating a waterproof membrane. The exception includes repairing small isolated leaks, where a single coat of most sealants will create a sufficient waterproof barrier.
A roof’s solar reflectivity is the amount of sunlight it’s capable of reflecting, which translates into less heat absorption, which equates to an overall cooler home, reduced air conditioning use, and a lower summer electricity bill. Depending on the sealant’s material and color, adding a layer of roof sealant to your roof can dramatically enhance your roof’s solar reflectivity. Some manufacturer’s claim that their products can deflect up to 92 percent of UV rays.
Rubber, acrylic, silicone, and polyurethane sealants all possess high levels of reflectivity. Along with the sealant’s material composition, the color of the sealant will play a major role in its level of reflectivity. White and light colored sealants generally possess the highest reflectivity, while black and darker colored sealants offer the lowest amounts of reflectivity.
A roof sealant’s longevity will vary among manufacturers and the sealant’s material, but most will last between 10 and 20 years. Sealant tapes will usually last this long without any special application process, but the longevity of liquid sealants depends on the thickness of the applied coating. A coating of liquid sealant that’s 30 millimeters thick can last 10 years longer than a sealant that’s 20 millimeters thick. Obtaining the proper thickness might require several coats of sealant, and sealant manufacturers will often specify the necessary amount of coats needed to obtain the desired thickness.
Another factor that impacts a roof sealant’s longevity is proper application; a roof sealant that’s applied during cold weather, to a wet or dirty roof, or before rain without adequate time to cure won’t last as long as a correctly applied sealant. Maintaining the performance includes inspecting the roof at least once a year under normal weather conditions and repairing any damage after adverse weather, like heavy rain, snow, and intense sun exposure. Some sealant manufacturers and roofing contractors recommend resealing your roof every five years, regardless of its condition, to maximize longevity.
Ease of Application
Thicker, solvent-based sealants, like silicone and some rubber sealants, are harder to apply than water-based sealants, like acrylic and some water-based rubber sealants. However, thinner sealants will likely require multiple coats to achieve the necessary thickness, especially when you’re trying to achieve a waterproof seal on your entire roof. Also, thicker sealants may be easier to work with in hot weather, since thin sealants might become too runny to achieve a required thick coat.
Both thick and thin sealants can be applied with a paint brush or roller, but with thinner sealants you have the additional option of using a paint sprayer. For isolated repair work, sealants in caulking tubes can more easily access nooks and crannies that would be difficult to reach with a brush, and sealant tapes can be easily applied to the affected area with minimal effort and no additional tools.
Our Top Picks
After becoming more familiar with the above considerations, you may be ready to start shopping and assess which roof sealant is right for you. To make selecting your sealant even easier, consider some of the following top picks categorized by roof type or need.
Regardless of your roof material or the climate, Liquid Rubber’s sealant is designed to protect it. It’s capable of creating a protective membrane on metal, shingle, or rubber roofs that are either flat or sloped. The sealant creates a rubber coating that is so resilient against standing water that it can be used on the bottom of ponds or gutters, so it should keep your roof protected from any possible amount of rain or snow. This sealant is also UV resistant, so it should also keep your roof protected from aggressive sun exposure.
Its water-based composition makes it incredibly easy to apply with a brush, roller, or sprayer, regardless of whether you’re repairing isolated leaks or sealing your entire roof. The main disadvantage is that it’s only available in the color black, which limits its solar reflectivity. Liquid Rubber offers a cost-effective and easy-to-use way to avoid expensive roofing repairs in the future.
If you need to repair only a small section of roofing and don’t want to purchase an entire container of liquid sealant, Gorilla’s 10-foot roll of seal tape might be just what you need. It creates a permanent bond that can patch a leak on a variety of roofing materials, including metal, rubber, plastic, and acrylic. While it works best if applied during dry and warm weather, it can be used during cold, hot, humid, and wet weather as well. It can even be applied underwater.
This seal tape is not designed to patch asphalt shingles and may not stick to a roof already treated with a liquid sealant or other water-repellent material. It also creates such a strong bond that attempting to remove this tape after it’s been applied might damage the underlying roofing material. However, with such a wide range of applications at such an affordable price, Gorilla’s seal tape is a solid budget option for patching small sections of damaged roofing.
To prevent small roof leaks from creating expensive damage down the road, Liquid Rubber’s seal tape can quickly and easily seal leaks on a variety of roofing materials. This seal tape comes in 2-inch wide strips with an adhesive backing that sticks to metal, shingles, and rubber. It can be applied without additional tools and doesn’t require any surface protection or cleanup, like other sealant types.
The main disadvantage is that this tape is only useful if you know where the leak is located; otherwise, you may need to use a whole roof treatment to seal visually undetectable leaks. It’s also not UV stable, so it will need an additional layer of liquid sealant to prevent UV degradation. However, using a small section of seal tape to repair minor cracks and holes is an easy and affordable option.
The gritty and jagged texture of asphalt roof shingles can make them especially hard to seal, and they require a sealant that will bind all the shingles together into a single, cohesive membrane. Sashco’s roof sealant does just that. With a roller or sprayer, its thin consistency can get into all the seams and potential leaks of every shingle.
It cures into a flexible, rubber compound that’s moisture proof and UV resistant and has a transparent finish. The cured rubber membrane lasts twice as long as the asphalt shingles it coats, which can drastically increase the lifespan of the protected shingles.
A leaky RV roof can quickly cause extensive damage to the RV’s interior, but Liquid Rubber’s roof coating is specifically formulated to protect against this costly problem. It creates a waterproof and solar reflective rubber coating over your RV’s rubber or metal roof, which should keep it cool during the summer and protected from weather damage during the entire year.
The rubberized membrane has a high level of flexibility, making it perfectly suited for the constant movement of an RV. One 5-gallon container is enough to provide two to three coats on the roof of an RV that’s up to 30 feet long, so you may only need a single bucket to seal your RV’s entire roof. If you only need to cover existing leaks or cover vulnerable seams, this sealant is also available in 1-gallon containers. It’s a thin, water-based formula that’s easy to apply, whether you use a paintbrush, roller, or paint sprayer.
Flat roofs are most susceptible to damage from standing water seeping inside any leaks or cracks. Preventing damage from ponding water on flat roofs is where Rubberseal’s roof seal really stands out. It provides a protective membrane that’s moisture resistant and virtually impenetrable to standing water, while also possessing high solar reflectivity to keep your roof cool and protected all summer long.
Rubberseal offers this sealant in a variety of colors, including white, black, light gray, and dark gray. The color options suit different aesthetic preferences and UV-resistance needs. It’s a thick solvent-based formula, so it’s easy to apply with a paint roller or brush but is likely too thick to use with a sprayer. While its thickness might make it harder to apply, it enables you to apply much thicker coats to make your roof as waterproof as possible.
For a roof sealant that’s specifically formulated for metal roofs, this option from Liquid Rubber is hard to beat. A water-based formula that can be applied with a brush, roller, or sprayer, it dries into a thick rubber membrane that’s incredibly moisture and UV resistant. The waterproof barrier it creates is resilient against pooling water, so it can be used on flat roofs as well as sloped.
The primary disadvantage is that its use is limited to just a handful of materials, but its specialized nature gives it an extra edge on metal roofs. It also can be used on concrete and wood in addition to metal.
Flashing is an important moisture barrier for your roof, but flashing that’s damaged by storms or age can leave your roof vulnerable to moisture exposure. Just like any other crack or leak in your roof, damage to your flashing needs to be repaired to restore the moisture-resistant integrity of your roof. Unfortunately, the gaps created by damaged metal flashing can be difficult to access with many roof sealants. Loctite’s roof flashing sealant was made specifically for this purpose.
As a caulk, it can access the small gaps created by damaged flashing, and the polyurethane sealant restores the flashing’s moisture-resistant function. It also functions as an adhesive, which means it will help close the gap between the flashing and your roof, which further assists in restoring your roof’s weather-resistant properties. This product isn’t the most versatile option on the list, but it serves its purpose of repairing metal roof flashing.
FAQs About Roof Sealants
With so many options available, you may still have unanswered questions about roof sealants. Before you start shopping, the answers to some of the most frequently asked questions below may help.
Q. How do you use roof sealant?
Depending on the thickness of the sealant you choose, you can apply it with a paintbrush, paint roller, paint sprayer, or hand trowel. Some roof sealants come in tubes that are applied with caulk guns.
Q. How long does a roof sealant take to dry?
The dry time for a roof sealant will depend on the sealant’s composition and the weather at the time of application. Most sealants take between eight and 24 hours to fully dry.
Q. How do you remove roof sealant?
You can usually use a plastic putty knife to remove roof sealant. Just be careful not to damage the underlying roofing material.