By Bob Beacham | Updated Feb 20, 2024 6:06 PM
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The main purpose of guttering is to channel rainwater away from the home and prevent it from damaging the foundation or seeping into the basement. During installation, rain gutter end caps and seams are coated with a flexible 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. However, gutter styles and materials vary considerably. What works well on vinyl, for example, may not be as effective on galvanized steel, aluminum, or copper. Plus, different kinds of damage require different repair techniques. One product may work better for pinholes or cracks, while another product may be required for a separated end cap.
As a result, we decided to test a variety of gutter installation and repair products, including exterior caulks, tapes, and roof sealants. They differ significantly in application methods and curing times, but each one is capable of creating a watertight seal on vinyl, PVC, and metal gutters. Whether your project involves new gutter installation or repairs and maintenance of old rain gutters, one of the following best gutter sealants available today will be able to handle the task.
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.
Our top picks feature a selection of the best gutter sealants on the market. 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.
Our tests proved the efficacy of the Geocel 2320 sealant. After loading it 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. This product adhered to anything it contacted, including concrete and wood as well as the gutter materials. 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.
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 sealant 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.
One of the most affordable gutter sealants we tested, Amerimax SeamerMate was easy to apply, easy to clean up, and formed an incredibly strong bond. Our drip-free caulking gun helped prevent messes. The product’s self-leveling consistency delivered professional-looking results, and it was paintable the day after application.
Although we preferred the final results of the Amerimax SeamerMate 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.
Get the Amerimax gutter sealant at The Home Depot, Ace Hardware, 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 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, or Lowe’s.
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, 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 or The Home Depot.
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, 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 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.
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.
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:
How well a particular sealant adheres to the gutter material is clearly of major importance. Most 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.
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.
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.
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.
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.
The information in this guide no doubt sheds some light on the various types of gutter sealants, how they work, and how to choose the best product for different challenges. During our research, however, several questions came up regularly—we’ve answered the most common ones succinctly below.
The gutter material, prevailing weather conditions, and the type of sealant all impact longevity. If applied carefully while paying close attention to the manufacturer’s instructions, a gutter sealant should last at least several years. Extreme cold or heat can reduce that time, but a careful product choice can maximize durability.
Use a caulk and sealant remover like Krud Kutter, mineral spirits, or lacquer thinner to remove old gutter sealant. Apply sparingly, allow it to soak in, and then lift with a putty knife or a chisel. Apply more remover if needed and wipe with a rag until you have a smooth, clean surface.
Some polyurethane sealants are safe to apply while moisture is present, though it is generally recommended to only seal gutters when they are dry. However, depending on the temperature, waiting 2 to 3 hours after the rain stops to apply sealant should be safe.
It depends on the product, so check the manufacturer’s instructions. Keep in mind that no type of gutter sealant should have prolonged contact with the skin, so it’s best to wear gloves. In particular, nitrile work gloves are reasonably tough yet thin enough not to restrict your movements.
Bob Vila has been America’s Handyman since 1979. As the host of beloved and groundbreaking TV series including “This Old House” and “Bob Vila’s Home Again,” he popularized and became synonymous with “do-it-yourself” home improvement.
Over the course of his decades-long career, Bob Vila has helped millions of people build, renovate, repair, and live better each day—a tradition that continues today with expert yet accessible home advice. The Bob Vila team distills need-to-know information into project tutorials, maintenance guides, tool 101s, and more. These home and garden experts then thoroughly research, vet, and recommend products that support homeowners, renters, DIYers, and professionals in their to-do lists.
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.
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