Gutters can spring leaks. It’s just the way it is. You can replace the leaky section, or in many cases, you can save time and money by patching or sealing the leak, provided you know what types of gutter patches and sealants to use.
It’s important to know that not all sealants are the same. There are different varieties to fix different problems. Perhaps the leak is caused by a hole, or maybe it’s the result of a bad joint or seam.
Caulk vs. Sealant
There are two basic products for closing wounds on gutters – caulk and sealant. Both terms are used interchangeably, both are used to fill cracks and gaps, and both can be applied with a caulking gun. The difference is elasticity.
Caulk is made of latex and acrylic materials, which makes it more rigid than sealants, which are made of silicone. Because of this, it’s prone to cracking, especially under high-temperature fluctuations, and thus it shouldn’t be used to seal gutters.
Types of Gutter Sealants
The best rain gutter sealants are either water- or solvent-based.
- Water-based sealants are thinner in consistency and easier to apply but need to be applied more frequently and degrade in half the time.
- Solvent-based sealants are thicker, adhere more quickly, and last longer. But they produce strong odors and can irritate skin and eyes, so wear gloves and safety goggles while using them.
There are multiple types of sealants, each with considerable differences:
Liquid Rubber Sealants
Versatile and water-based, liquid rubber sealants offer all the benefits of their solvent-based counterparts without toxicity. You apply them with a brush or roller.
These sealants create watertight seals, which prevent moisture from escaping. They’re paintable and can be used both indoors and outdoors. They’re also UV-stable, meaning the sun’s rays don’t damage them.
However, they can take up to 48 hours to dry after being applied, and when they do dry, they turn black or brown, making them less pleasing to look at. Additionally, you may need to apply more than one coat.
Example: Liquid Rubber Waterproof Sealant
| Pros | Cons |
| ✓ Paintable | ✗ Slow to dry |
| ✓ Non-toxic | ✗ May need more than one coat |
| ✓ Flexible | ✗ Not aesthetically pleasing to look at after drying |
| ✓ Resilient against the sun’s rays |
Butyl Rubber Sealants
Butyl rubber sealants are effective in temperatures from 20 to 120°F and on both wet and dry surfaces. They adhere quickly and remain flexible after drying. This allows them to flex with the gutter as it expands and contracts, all while ensuring a watertight seal.
However, they take a little skill to apply, as they’re dispensed from a caulking gun. Additionally, if left uncovered, they dry out quickly as they don’t have a cap. Furthermore, while they can withstand high temperatures, they lack UV protection.
Example: DAP 18377 3.0 Crystal Clear Premium Gutter and Flashing Sealant
| Pros | Cons |
| ✓ Handle cold and hot temperatures | ✗ Hard to squeeze out of the tube |
| ✓ Work on wet and dry surfaces | ✗ Dry out quickly |
| ✓ Remain flexible after drying | ✗ No UV protection |
| ✓ Don’t shrink or crack as the gutter moves. |
(Poly)urethane-Based Sealants
Urethane-based sealants are designed specifically for sealing around galvanized, vinyl, and aluminum gutters. They have strong chemical and weather resistance and plug up cracks and holes of all sizes. Additionally, they can be easily painted and resist mildew.
Urethane-based sealants take anywhere from one to two days to fully dry. Apply them carefully, as they need to be installed and cured correctly to last a long time.
Example: DAP Dynaflex Gutter & Narrow Seam Advanced Elastomeric Waterproofer
| Pros | Cons |
| ✓ Resist mildew | ✗ Needs to be installed carefully |
| ✓ Flexible | ✗ Takes 1-2 days to dry |
| ✓ Strong chemical and weather resistance | |
| ✓ Easy to paint |
Seal Tape
Unlike the other products, this one is a tape, making it easy to apply: just tape over the leak. It’s designed for multiple surfaces, including wood, glass, and acrylic. Regardless of the surface, it seals large holes and cracks on pool liners, roofs, gutters, and vehicles.
Seal tape is versatile; it can be used indoors, outdoors, and even underwater. It also has strong UV and weather resistance, as it resists sunlight and temperatures ranging from -70 to 200°F.
Even though it can be applied wet, it works best on dry surfaces because adhesion to wet surfaces is always a little iffy. It should also be applied to smooth surfaces rather than rough surfaces. Finally, it’s very sticky, so it can be tough to cut with scissors.
Example: Gorilla Waterproof Patch & Seal Tape
| Pros | Cons |
| ✓ Versatile | ✗ It can fail when applied to wet surfaces |
| ✓ Repairs instantly | ✗ Hard to cut with scissors due to stickiness |
| ✓ Withstands sunlight, freezing, and high temperatures | ✗ It doesn’t work on rough surfaces |
| ✓ Can be applied underwater | |
| ✓ Flexible |
How to Pick the Right Patch or Sealant
Choosing the right gutter sealant is challenging. No sealant is better than the other. The gutter material is the main factor, but other factors are involved, such as the location and type of leak, prevailing weather conditions, drying time, and flexibility of the final seal.
Here is what all the sealants have in common:
Adhesion strength and surface
How well a sealer adheres to the gutter material is crucial. No single sealant is best for all surfaces, and some don’t stick to certain surfaces at all. Check your gutter sealant’s compatibility before applying it.
The most common types of gutter materials are vinyl and aluminum, but galvanized steel, zinc, and copper are also used.
Note that general-purpose sealants are a jack-of-all-trades, master of none. They are very versatile, but generally aren’t the best sealant for the job compared to more specialized options.
Dry time, flexibility, and durability
When choosing a sealant, you should be cognizant of its drying time, its flexibility properties, and its durability.
Drying Time: Gutter sealants require anywhere from under an hour to two days to dry and cure. That makes a big difference if you want to paint over them as soon as possible. If you have to complete the job quickly, then you may opt for a quick-drying product.
Flexibility: A sealant’s flexibility is crucial to its success. Gutters frequently shift due to wind, and temperature changes can cause them to expand and contract, compromising the integrity of the repair. If you live in a region prone to extreme temperature fluctuations, choose a formula that will flex with the gutter or gutter seam. This particularly applies to metal gutters, which expand and contract under fluctuating weather.
Durability: Durability also extends to protection from the elements. For example, UV-resistant sealants are protected from the sun’s rays. Sealants with chemical resistance are also worth looking into. For instance, if you live in a coastal area, look for a sealant with resistance to salt.
Versatility
Sometimes, you just need to do a simple gutter repair. If that’s the case, it might be more economical to buy a more versatile sealant. Some sealants can be used for a variety of coating and repair purposes, such as sealing around window frames and fixing holes in pool liners.
If you need such a sealant, check its shelf life before buying it. Some sealants have a shorter lifespan once opened, and it’s frustrating to use them to repair your gutters only for them to harden and become useless six months later if you need them for another task.
Frequently Asked Questions
It depends on the type of gutter, weather conditions, and the type of sealant used. Some brands offer a lifetime guarantee, while others last anywhere from one to four years.
Some polyurethane sealants can be applied to wet gutters. However, it’s generally recommended to wait until your gutters are completely dry before applying sealant. If waiting isn’t an option, apply the sealant two to three hours after the rain stops.
Use a sealant remover, mineral spirits, or lacquer thinner. Apply a small amount, allow it to sit, and remove it with a putty knife or chisel. Repeat the process if necessary, and wipe away any remaining residue until you get a smooth, clean surface.
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Main Image: Man applying sealant to the leaky joint of a rain gutter. Photo Credit: Anna Kapustina / Adobe Stock
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