By Bob Beacham | Updated Apr 1, 2022 3:25 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. But the gutters themselves are subject to all kinds of harsh weather conditions, which could cause them to leak.

There are several effective approaches to fixing rain gutter leaks and plenty of different gutter sealants available. 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.

Exterior caulks and roof sealants are often suggested as cost-effective solutions—and it can be tempting to use them if there’s some leftover from other jobs—but are they really the correct choice? This comprehensive guide will provide the info you need and help you choose the best gutter sealants for a range of different materials.

There are several challenges when trying to choose the best gutter sealant. While gutter material is a key factor, the position and type of leak can affect choice, too. Prevailing weather conditions, curing time, and the flexibility of the final seal also play a part. Here’s what all the best gutter sealants have in common—as well as what might make one type better for a particular job than another.

Before discerning between types of sealants, it’s important to recognize that caulk and sealant are two entirely different products. Caulk usually comes in a tube and is applied using a caulking gun. Acrylic caulks are water-based and paintable, but they lack the flex of sealants. As a result they are more prone to cracking, particularly under wide temperature fluctuations, so they should not be used to seal gutters.

The best rain gutter sealant can be either water- or solvent-based. Some of the latter give off strong odors and can be irritating, so gloves and eye protection should be worn during use.

Different sealants can vary considerably:

How well a particular sealant adheres to the gutter material is clearly of major importance. Vinyl and aluminum gutters are most common, but galvanized steel, zinc, and copper are also used. Some products don’t stick to particular surfaces at all, and while general-purpose sealants can be very versatile, no single product is the best gutter sealant for all materials. 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 what the surface, preparation will be key. Pretty much all of the best gutter sealant reviews mention 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 about 2 days to dry completely. That can make a big difference if there’s only a short time window for the repair, especially if it also needs to be painted.

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 just about surviving freezing temperatures but also the range of temperatures the repair will have to endure. Metal gutters in areas where there is a wide fluctuation in weather conditions can be particularly challenging because of the amount they expand and contract.

It’s worth checking for 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 in coastal areas.

There are numerous products designed to seal gutters and nothing else. Others, however, can be used 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 to do, it may be economical to purchase a versatile sealant that could come in handy down the line.

Just be sure to check shelf life before investing in a large can of multipurpose stuff. Some of these products have a limited useful lifespan once opened, so while it might be great for a gutter repair now, in 6 months, when a different task arises, the contents might have hardened and become useless.

The gutter sealant chosen should come with instructions, which must be followed as closely as possible. But in terms of basic advice, the following tips should help ensure a successful gutter repair.

The list below features some of the best gutter sealants on the market. We took into account each product’s value, effectiveness, and environmental impact.

A number of paintable, rubberized gutter seals on the market can be very effective but, unfortunately, many are solvent-based. Water-based Liquid Rubber has virtually no odor yet all the benefits of its toxic competitors.

Liquid Rubber can be applied with a roller or even sprayed (though the latter requires professional-grade equipment). It sticks well to vertical as well as horizontal surfaces, and the ability to deform without splitting or cracking means it will flex as much as necessary without compromising adhesion. It is UV stable so it will not be damaged by the sun’s harmful rays, and it can be painted.

Depending on the size of the repair, it may need two coats, and drying time means it can take several days to fully complete the repair.

Get the Liquid Rubber gutter sealant on Amazon.

Gorilla’s waterproof tape provides a durable repair virtually immediately. It is 4 inches wide, a good size for substantial cracks or splits, and is arguably the best way to seal gutter seams. The adhesive grip is very high on all gutter materials. It is UV resistant, and once fixed it can withstand temperatures from as low as -70 degrees Fahrenheit up to 200 degrees Fahrenheit. There are 10 feet of tape per roll, and it will store almost indefinitely if kept in an airtight bag.

Although the manufacturer states that it can be applied wet, dry surfaces are recommended, as repairs made on damp surfaces have been known to fail. The surface also needs to be sound; if it’s dusty or flaking the tape will lift. Be sure to cut the tape to fit with the backing still in place; otherwise, the tape is likely to stick to the knife or scissors and can be very difficult to remove.

Get the Gorilla gutter sealant at Amazon, The Home Depot, and Walmart.

There can be definite advantages to using a caulking gun to apply sealant such as this DAP product. A gun is particularly good for injecting sealant into gaps and cracks, and this technique may also mean less waste than brushing.

DAP 18377 is a gel-type clear sealant that’s relatively easy to use on dry or damp surfaces. It dries in just 30 minutes and it can be painted. (Several competing products offer a range of colors, but they seldom match existing gutters accurately.) It will withstand temperatures from 20 degrees Fahrenheit to 120 degrees Fahrenheit, more than adequate for all but the most extreme environments. One caveat: There is no information on UV resistance.

Get the DAP gutter sealant on Amazon and at Walmart.

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

Rust-Oleum is touch dry in around 30 minutes, and a second coat can then be applied if necessary. For example, it may successfully fill gaps up to ¼-inch wide, but more than one application would be required. It then takes 24 hours to fully cure. Rust-Oleum LeakSeal is available in five colors and can also be overpainted with latex or oil-based paint.

Get the Rust-Oleum gutter sealant on Amazon and at Walmart.

General-purpose products are often capable, but specialist alternatives invariably provide a better solution. GE5050, for example, is formulated particularly for metals. It is a silicone-based sealant that can be applied with great accuracy and economy using a caulking gun. It flows easily into gaps, seams, and cracks, and the initial drying time is very rapid. It is waterproof in around 30 minutes, though a full cure takes 24 hours.

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

Although odor-free once cured, it gives off an unpleasant vapor during the application, so a breathing mask should be worn during use. It can also irritate the skin, so gloves and eye protection are equally important.

Get the GE gutter sealant on Amazon and at Walmart.

Liquid Rubber’s sealant will fix leaks in any type of gutter, and it is durable and environmentally friendly. Its versatility also makes it a great value. Gorilla tape is a virtually instant fix in almost all conditions, but it’s so sticky it can be difficult to work with.

Many DIYers have at one time or another been up a ladder cleaning a blocked gutter or attempting to fix a leak. In assessing the best gutter sealants currently available, the following criteria were considered.

Manufacturer information is helpful, but in order to assess real-world performance and durability we felt it important to review feedback from actual buyers. Products with significant application problems or failures did not make the cut. It is not always possible to select environmentally-friendly products so wherever quality water-based products were available, they were chosen over solvent-based products.

Value isn’t just about the cost per amount of a product. Generally speaking, even small containers could provide enough product for a single repair. So we also considered if the gutter sealer could be used for other tasks, thus offering better value for money.

The information presented above no doubt clued you in about the various types of gutter sealants, how they work, and how to choose the best product for different challenges. During our research, however,  a number of questions came up regularly—we answer the most common ones succinctly below.

The type of gutter, prevailing weather conditions, and the type of sealant all impact longevity. If applied carefully while paying close attention to manufacturer instructions, it should last at least several years. Extreme cold or heat can reduce that time, but careful product choice can maximize durability.

Use a caulk and sealant remover like Krud Kutter, mineral spirits, or lacquer thinner. Apply sparingly, allow to soak in, then lift with a putty knife or an old chisel. Apply more remover if needed and wipe with a rag until you have a smooth, clean surface.

Some polyurethane sealants can be applied while moisture is present, though in general it is recommended that gutters are dry when sealed. This may vary depending on temperature but probably 2 to 3 hours after the rain stops.

It depends on the product, and instructions should be provided on the packaging. However, none of these sealants is particularly good for your skin so we recommend protecting your hands in the first place with nitrile work gloves. These are reasonably tough yet thin enough to allow for a good feel and not restrict your movements.

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