The Best Gutter Sealants, According to Our Hands-On Tests

During installation, rain gutter end caps and seams are coated with a flexible gutter sealant designed to withstand hot and cold weather and moderate impacts. However, the gutters themselves are subject to all kinds of harsh conditions, which, combined with aging, could inevitably cause them to leak. Several effective approaches to fixing rain gutter leaks and plenty of different gutter sealants are available to consumers. As a result, we decided to test a variety of gutter installation and repair products, including exterior caulks, tapes, and roof sealants.

Gutter styles and materials vary considerably. What works well on vinyl, for example, may not be as effective on galvanized steel, aluminum, or copper. With that in mind, our top pick is the Geocel 2320 Tripolymer Gutter and Narrow Seam Sealant, which adheres to all types of rain gutters and can seal gaps up to ¼ inch in diameter.

Whether your project involves new gutter installation or repairs and maintenance of old rain gutters, one of the following best gutter sealants that we put through rigorous testing will be able to handle the task. 

1. BEST OVERALL: Geocel 2320 Tripolymer Gutter and Narrow Seam Sealant
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2. BEST BANG FOR THE BUCK: Amerimax SeamerMate Gutter Sealant
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3. BEST FOR LEAKS: Liquid Rubber Waterproof Sealant
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4. BEST QUICK FIX: Gorilla Waterproof Patch & Seal Tape
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5. BEST MULTISURFACE: OSI Quad Max Clear Paintable Sealant
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6. BEST FOR METAL GUTTERS: GE Metal Silicone 2 Sealant
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7. BEST SPRAY: Rust-Oleum LeakSeal Spray
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8. BEST TAPE: XFasten Super Waterproof Aluminum Butyl Tape
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9. ALSO CONSIDER: Flex Seal Spray-On Liquid Rubber Sealant
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Gutter Sealant Comparison

Our Top Picks

Our top picks feature a selection of the best gutter sealants on the market, perfect for adding to your gutter repair kit. We took into account each product’s effectiveness, value, and environmental impact. While each gutter sealant is a quality product, read on to discover which one may best suit your particular needs.

Our Ratings: Application 4/5; Cleanup 4/5: Cure Time 3/5; Durability 5/5

Building professionals use Geocel 2320 tripolymer sealant because it’s durable and takes the guesswork out of gutter installation and repair projects. It adheres to all types of material, works in any weather, and fills gaps up to ¼ inch in diameter. The self-leveling formula flows deep into the gaps and cures to form a tough yet flexible bond. Each 10-ounce tube contains enough product to extrude a ¼-inch bead of sealant up to 28 feet, using a standard caulking gun. 

After loading the Geocel 2320 rain gutter sealant​ in the caulking gun, we squeezed a few small beads of the sealant into the holes we had drilled in the bottom of the gutter, then installed two end caps. It was easy to control the pressure and prevent messes via the dripless feature on the caulking gun. Even though our initial finish was not perfect, the self-leveling texture allowed the ridges and bumps to settle into a fairly smooth finish.

The only downside to this product was the cure time. Although a surface skin began to form within an hour, it was extremely pliable for 24 hours. However, after the 5-day cure time, the sealant was very sturdy, puncture-resistant, and fully waterproof.

What our tester says: “My tests proved the efficacy of the Geocel 2320 sealant. This product adhered to anything it contacted, including concrete and wood as well as the gutter materials.”–Mark Wolfe, Product Reviews tester and writer

Get the Geocel gutter sealant at Amazon.

Our Ratings: Application 4/5; Cleanup 4/5; Cure Time 3/5; Durability 5/5

The Amerimax SeamerMate gutter caulking is a high-quality tripolymer product for metal gutters. Be aware that it is designed to bond metal to metal and may damage other gutter materials. Applied with a caulking gun, the self-leveling formula fills gaps and holes up to ¼ inch and leaves a smooth, tough finish. This sealant is designed for secure gutter installation and repairs that can withstand harsh weather for decades. 

Although we preferred the final results of the Amerimax SeamerMate rain gutter caulking over most of the other products, the slow cure time of up to 5 days might be problematic for some users. Also, for a single small repair, the full 10-ounce tube could be excessive, and there is no way to reseal it for later use once you’ve opened it. Still, this sealant is a great product at a great price, best for midsize and larger repairs.

What our tester says: “One of the most affordable gutter sealants I tested, Amerimax SeamerMate was easy to apply, easy to clean up, and formed an incredibly strong bond. The product’s self-leveling consistency delivered professional-looking results, and it was paintable the day after application.”–Mark Wolfe, Product Reviews tester and writer

Get the Amerimax gutter sealant at The Home Depot, Ace Hardware, Walmart, or Amazon.

Our Ratings: Application 4/5; Cleanup 3/5; Cure Time 4/5; Durability 4/5

While a number of paintable, rubberized gutter sealants on the market are very effective, many are unfortunately solvent-based. Water-based Liquid Rubber flexible gutter sealant has virtually no odor yet all the benefits of its more toxic competitors.

You can apply Liquid Rubber with a roller or even a piston sprayer—although the latter requires professional-grade equipment. This product adheres well to both vertical and horizontal surfaces, and the ability to perform without splitting or cracking means it will flex as much as necessary without compromising adhesion. Liquid Rubber is UV-stable, so the sun’s harmful rays won’t damage it.

Depending on the size of the repair, it may need two coats, and a slow drying time means it can take several days to fully complete the repair. In our tests, the first coat felt dry after 12 hours, but we waited the full 24 hours before applying another coat. In all, we applied three coats over the ⅛-inch and ¼-inch holes in the bottoms of our gutters, but two coats would have been adequate. We filled the gutter with water 2 days after the last application, and it held fast. You can paint over this sealant once it’s fully dry.

Get the Liquid Rubber gutter sealant at Amazon, Lowe’s, The Home Depot, or Walmart.

Our Ratings: Application 3/5; Cleanup 5/5; Cure Time 5/5; Durability 4/5

Gorilla waterproof tape provides a durable repair virtually immediately. It is 4 inches wide—a good size for substantial cracks or splits—and is one of the best ways to seal gutter seams. The adhesive grip is very effective on all gutter materials. This product is UV-resistant and can withstand temperatures as low as -70 degrees Fahrenheit up to 200 degrees Fahrenheit. Each roll is 10 feet long, and it will store almost indefinitely in an airtight bag at room temperature.

Although the manufacturer states that you can apply Gorilla tape to wet surfaces, our tests revealed that only dry surfaces work well. The surface also needs to be sound: The tape will lift if the surface is dusty, flaking, or slimy. We had to cut the tape to fit with the backing still in place; otherwise, the tape stuck to the knife or scissors and was very difficult to remove. It’s also important to use caution while positioning the tape. Once we placed the tape, it was nearly impossible to remove.

One downside is that the Gorilla tape didn’t blend well with the gutter surface. The thick profile of the tape stood out, as did the pure white color against the patina of our 50-year-old gutters. Additionally, this product is not paintable and so is best used on the inside of the gutter, if possible, to hide the repair. 

Get the Gorilla gutter sealant at Amazon, Ace Hardware, The Home Depot, or Walmart.

Our Ratings: Application 4/5; Cleanup 4/5; Cure Time 4/5; Durability 5/5

Primarily labeled as a window, siding, and door sealant, OSI Quad Max is also highly rated for gutter sealant applications. It has a higher viscosity than other gutter sealants to allow for faster setup and creates a tough watertight bond that stands up to UV rays, dust, dirt, and extreme weather. This product is an excellent choice if you need to keep a project moving quickly, as it is paintable within an hour and cures fully in as little as 24 hours.

During our tests, we noted stiffer resistance on the caulking gun while applying OSI Quad Max sealant compared to most of the other gutter-tested products. This sealant is also less forgiving of sloppy work. Since it isn’t a self-leveling sealant, it didn’t flow downward into the voids quite as thoroughly, and any imperfections in the bead were likely to remain after curing if we didn’t take the time to smooth them out. However, once cured, our end caps and drilled holes stayed watertight.

Get the OSI Quad Max gutter sealant at Lowe’s, The Home Depot, Ace Hardware, or Walmart.

Our Ratings: Application 4/5; Cleanup 4/5; Cure Time 4/5; Durability 4/5

While general-purpose products are often capable, specialist alternatives invariably provide a better solution. This GE sealant caulk for gutters​, for example, is formulated particularly for metals. It is a silicone-based sealant that we applied with great accuracy and economy using a caulking gun during our tests. It flowed easily into gaps, seams, and cracks, and we found the initial drying time to be very rapid. This product is permanently waterproof in around 30 minutes, although a full cure takes 24 hours.

The silicone component keeps the sealant flexible, so it will not shrink or crack. It has high UV resistance and can withstand temperatures from -60 degrees Fahrenheit to a staggering 400 degrees Fahrenheit.

Although odor-free once cured, the GE silicone gutter sealant does emit an unpleasant vapor during application, so it’s important to wear a mask during use. It can also irritate the skin, so gloves and eye protection are equally necessary.

Get the GE gutter sealant at Amazon, Lowe’s, The Home Depot, or Walmart.

Our Ratings: Application 5/5; Cleanup 4/5; Cure Time 4/5; Durability 3/5

Rust-Oleum LeakSeal gutter sealant spray contains butyl rubber, which is known for flexibility and high adhesion. Spraying it on is an easy and convenient way to handle small gutter repairs. 

This product is dry to the touch in about 30 minutes, and you can apply a second coat, if necessary. For example, it may successfully fill gaps up to ¼-inch wide, but more than one application would be required. The sealant then takes 24 hours to fully cure. Rust-Oleum LeakSeal is available in five colors and can also be painted over with latex or oil-based paint.

As with the tape and paint-on products, this spray sealant is not designed for attaching end caps. However, it did a thorough and relatively quick job of patching pinholes and bridging joints.

What our tester says: “In my tests, Rust-Oleum LeakSeal spray went on as easily as advertised, with a tight spray pattern that helped minimize overspray. I used a scrap of cardboard to shield the peripheral area, and it worked well. The sealant filled both the ⅛-inch and ¼-inch holes in a single application, but I added a second coat to increase strength.”–Mark Wolfe, Product Reviews tester and writer

Get the Rust-Oleum gutter sealant at Amazon, Ace Hardware, Tractor Supply Co. (black), or Walmart.

Our Ratings: Application 4/5; Cleanup 5/5; Cure Time 5/5; Durability 4/5

Waterproof butyl tape makes gutter repair fast and easy. XFasten aluminum butyl tape has a unique “quilted” backing that allows the tape to conform to textured or uneven surfaces. The thick adhesive side embeds into surface voids for a perfect watertight fit, and the aluminum side is highly puncture-resistant. The roll measures 16 feet long by 4 inches wide and has a 5-year storage life, making it an ideal choice for storage in an emergency repair kit.

To cover our ⅛-inch and ¼-inch holes, we cut ½-inch by ½-inch squares of the XFasten tape. Because the weather was cool and dry, we were easily able to remove the backing and place the adhesive patches over the holes. The tape held water instantly. Next, we added a seam test by overlapping two gutter system sections—the end of one section nested inside the matching end of the other section, overlapping by 4 inches. We taped the seam from the outside, with the XFasten tape centered on the seam. Then, we taped the inside seam the same way. The tape provided a perfectly drip-free seal while strengthening the joint. 

The main problem with the XFasten tape was that the sides of the roll, where the adhesive was marginally exposed to air and handling, became extremely sticky. This made the roll more difficult to handle, especially while taping interior seams. Still, the end result was a strong waterproof patch that was ready within seconds instead of hours or days.

Get the XFasten gutter sealant at Amazon or Walmart.

Our Ratings: Application 5/5; Cleanup 4/5; Cure Time 4/5; Durability 3/5

Flex Seal sealant has been an infomercial staple for years, and it works as advertised for rain gutter and downspout repairs. This rubberlike product goes on like spray paint and becomes a tough, flexible, watertight skin that resists sagging and dripping in hot weather and won’t crack in cold weather. It’s a great choice for quick repairs of leaky seams and pinholes.

Since our testing period was in late November, we took note of one instruction in particular. Flex Seal requires an air temperature of at least 65 degrees Fahrenheit during application, so we performed our testing on a warm afternoon.  After applying the first coat, we waited 24 hours before applying a second coat. After another 24 hours, we tested the seal. It worked perfectly on the ⅛-inch and ¼-inch holes as well as the overlapped seam. The gutter was leak-free, and the cured spray showed a fair amount of toughness against attempts at scraping with a paint scraper and puncturing with a finishing nail.

We didn’t love that Flex Seal sealant required mild temperatures for application. However, we did like how easy it was to apply and how effective it was once cured. This product is also useful for a wide range of household projects, so it could be a handy item to have available.

Get the Flex Seal gutter sealant at Amazon (2-pack), Lowe’s, Tractor Supply Co., Ace Hardware, The Home Depot, Walmart, or Staples.

How We Tested the Best Gutter Sealants

We simulated gutter installation and gutter leak repairs in our tests and evaluated how each product performed on aluminum and PVC gutters. Using salvaged sections of aluminum and PVC gutters, we first drilled a series of ⅛-inch and ¼-inch holes in the gutter bottoms and applied the sealant product to repair the holes. Then, we used each product to install gutter end caps on both gutter types.

Throughout testing, we made sure to strictly follow the manufacturer’s instructions for each sealant. During the application process, we noted both whether the product was clean or messy to use and how easy or difficult it was to clean up afterward. We also noted the number of applications required, the cure time for each application, the total cure time, and overall durability. After we completed all applications and installations, we filled the gutters with water, observed the water level for 12 hours, and noted any leaks. Finally, we scored each gutter sealant on a scale of 1 to 5 for ease of application, ease of cleanup, quick results, and durability.

What to Consider When Choosing a Gutter Sealant

There are several considerations to keep in mind when choosing a gutter sealant. While the gutter material is a key factor, the position and type of leak can also impact your selection. Prevailing weather conditions, curing time, and the flexibility of the final seal also play a part. Here are the characteristics that the best gutter sealants have in common—as well as what might make one product better for a particular job than another.

Type

Before discerning between types of sealants, it’s important to recognize that caulk and sealant are different products. Caulk usually comes in a tube, which you apply using a caulking gun. Acrylic caulks are water-based and paintable, but they lack the flexibility of sealants. As a result, they are more prone to cracking—particularly under wide temperature fluctuations—so avoid using acrylic caulks to seal gutters.

The best rain gutter sealant can be either water- or solvent-based. Some of the latter emit a strong odor and can be irritating to the skin, eyes, and nasal passages, so be sure to wear gloves, eye protection, and a mask during use.

Different sealants can vary considerably:

• Paste sealants most closely resemble caulks. Often silicone-based, they are frequently used for aluminum and other metal gutters and are most often applied with a caulking gun.
• Liquid rubber sealants are versatile, water-based, multisurface products applied with a brush or a roller.
• Spray-on sealants apply quickly and easily over small areas. They are often similar in composition to liquid rubber sealants, though they tend to be more expensive.
• Sealant tapes are another rapid adhesion, multisurface solution. Some sealant tapes may be less durable than other types of sealants.

Adhesion Strength and Surface

How well a particular gutter seam sealant​ adheres to the gutter material is clearly of major importance. Most types of rain gutters are made of vinyl or aluminum, but some gutters are constructed of galvanized steel, zinc, or copper. Certain sealants may not stick to particular surfaces, and while general-purpose sealants can be versatile, no single product is the best gutter sealant for all materials. Thus, it’s vital to check compatibility. Failure to do so may mean a temporary fix, but adhesion strength will be compromised and the leak might soon reappear.

No matter the gutter material, preparation will be key. Nearly all of the best gutter sealant reviews emphasize the need to follow the manufacturer’s instructions carefully, and we echo that advice: It’s essential to read and follow directions to avoid failure of the repair.

Dry Time, Flexibility, and Durability

Gutter sealants can require anywhere from under an hour to up to several days to dry completely. That can be a big difference if there’s only a short time window for the repair, especially if you also need to paint the gutter.

Generally speaking, a degree of flexibility in a sealant is beneficial because gutters are subject to movement from wind and temperature changes. Flexibility can also impact the durability of the fix. It’s not only about surviving freezing temperatures but also the wide range of temperatures a repair may have to endure depending on the part of the country in which you live. Metal gutters in areas that experience extreme fluctuation in weather conditions can be particularly challenging because of how much they will expand and contract.

It’s worth considering a sealant that contains UV inhibitors, which give increased protection against the harmful effects of the sun’s rays. Chemical resistance can also be beneficial. Salt, for instance, can be a problem for homes in coastal areas.

Versatility

Numerous products are designed to seal gutters and nothing else. Shoppers can purchase other products, however, for various coating and repair purposes—from sealing around window frames to fixing holes in pool liners. If you only have a modest gutter repair, it may be economical to purchase a versatile sealant that could come in handy later for another home improvement project. However, it’s also wise to be wary of multi-use products that won’t stand up long term for gutter sealing, like traditional expanding foam, for example.

Still, be sure to check shelf life before investing in a large can of multipurpose sealant: Some of these products have a limited useful lifespan once opened. In these cases, a sealant might work well for gutter repair now, but when a different task arises in a few months, it might have hardened and become useless. 

Tips for Using Gutter Sealants

As noted above, remember to follow the manufacturer’s instructions as closely as possible for any gutter sealant you purchase. In terms of basic advice, the following tips should help ensure a successful gutter repair.

• Cleaning gutters once every 6 months will help identify damage early on and allow for repairs before major problems arise.
• Try to only apply a gutter sealant on top of existing repairs or surfaces that are damp in an emergency. Ideally, the gutter should be clean, dry, and free of any previous product.
• Ensure that the waterproof gutter sealant thoroughly penetrates cracks and seams rather than just lying on the surface.
• If the joint in need of repair will not hold together on its own, apply clamps or binding while the sealant cures. Depending on the product, curing can take several days.
• While gutter sealants can be very effective and often handle large repairs, there are limits. Sometimes, the best solution is to replace a section of the gutter.

FAQs

Meet the Tester

Mark Wolfe is a writer with an extensive background in the green industry and an avid DIYer who lives in a 50-year-old home. When he isn’t writing, he spends his time upgrading, repairing, and replacing anything and everything in his home, yard, and garden. He tests and writes reviews about hand tools, lawn care and home repair products, and outdoor living goods.

Additional research provided by Bob Beacham.

 

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