The Best Sealant for Leak-Proof Gutters

Let’s face it. Leaky gutters are not fun to deal with.

It is normal for the sealant on your gutters to wear away and for leaks to form after a while.

Worn down sealant is one of the #1 causes of gutter leaks.

There are a ton of sealant types to choose from and it can be overwhelming trying to choose the best.

So we narrowed it down to the best options that will make sure your gutters are leak-proof for the long haul.

Here is our list of the very best gutter sealant/caulk options.

Our Top Picks

When choosing sealants there are so many options to pick from. We tried to find gutter specific sealants to make sure they last for the long haul.

We also included more general options that way you can find some in your local hardware store, such as Home Depot or Lowes.

1. Geocel 2320 Sealant – Best Overall

Geocel 2320 best gutter sealant

When it comes to gutter sealants, Geocel is the best option.

It is the industry standard for gutter sealants. Why, you may ask?

Geocel 2320 creates a leak-proof joint when applied to your gutters. As your gutters get exposed to extreme heat and cold, they will shift and move over time.

This gutter sealant moves with your gutters as they undergo the stress of being outdoors.

It’s called “self-leveling”. An important feature as your gutters will move more than you expect during their lifespan.

And Geocel 2320 moves with them.

The chemical properties promote a tight seal between the gutters and the sealant.

As the sealant gets blasted by ultraviolent light from the sun over it’s lifespan, the 2320 can resist it.

In fact, it’s made to have a high ultraviolent resistance.

You can also paint over the sealant, if you plan on doing so.

When applying the sealant, you want your gutters to be dry and clean for a tight bond.

And it’s expected your sealant will last for a long time depending on your climate.

But the real secret lies in the “tri-polymer blend”. Meaning it’s not water or rubber-based, but instead it’s a proprietary blend.

We don’t know what it’s actually made up of (because it’s a secret) but it’s basically liquid gold for you gutters. If you want to check it out, you can find the Geocel 2320 linked here for an affordable price.

2. Liquid Rubber Waterproof Sealant

liquid rubber sealant for gutters

Liquid rubber is an excellent option for gutter sealant. It’s used by contractors for roofing, shingles, and gutters.

Any part of your house that gets blasted by sunlight, the liquid rubber sealant will do wonders.

It’s made to be ultraviolent resistant.

The liquid rubber sealant is water-based, safe, and super easy to use.

No complicated steps to apply it and it’s not dangerous at all.

In some cases (if the gap your sealing is large), you may need to apply two coats for a longer-lasting seal.

This can increase the time it takes do the gutter repairs. It might stretch your project an extra day as you wait for the first coat to dry.

But it’s an excellent option to consider.

3. DAP Gutter and Flashing Rubber Sealant

Dap gutter sealant

This one is another rubber sealant, like the last one.

I’m noticing a trend here…

The Dap 14777 Gutter Sealant is UV-resistant and paintable. Both things we are looking for when it comes to gutter sealant.

It’s also flexible and shrink-proof, meaning that the seal will water-proof for longer.

Wither other caulk types, they will shrink when exposed to different weather conditions. This type will stay sealed for longer.

It’s also less likely to develop mold or mildew as it ages. This is common with sealants that get exposed to high amounts of humidity and water.

4. Rust-Oleum 267970 LeakSeal Rubber Sealant

rustoleam rubber sealant for gutters

If you’re looking for a cheaper option that’s widely available in big box stores, this is for you.

The Rust-Oleum 267970 is another rubber based sealant that will work your gutters.

Like other gutter sealants, it’s paintable and UV-resistant, perfect for your gutters.

This was not made for gutters, but instead roofing projects in general. So it may not last as long as the other gutter caulk options.

The benefit to this sealant is how affordable it is and how easy it is to get it.

Not to mention, it’s one of the easier options to apply as a DIY project.

But you won’t see many professional gutter contractors use this sealant as it’s not quite as good.

5. Flex Seal – Only for Emergencies

Flex seal sealant

Last, we have Flex Seal.

Now, it’s not recommended to use Flex Seal for your gutters unless it’s an emergency. Flex Seal, while the container says rubber-based, is really more like a silicone based sealant, which is not recommended for gutters.

Silicone will not last very long if used for your gutters. You can expect it to last a year or two at the most.

And it creates other issues as well. If you have used Flex Seal in the past, you will need to remove all the old sealant. Otherwise it can mess with the water-proof seal of future projects.

It’s recommended to clean it out with a wire brush, making sure to get all the existing Flex Seal. Flex Seal does not last very long because it’s not made to move, shrink, and expand like other rubber sealants. It’s also not as UV-resistant, meaning sunlight will wear it down fast.

Now, if all you have on hand is Flex Seal, you can use it in a pinch for an upcoming storm. But you should expect that you will need to repair it in a year or so (or sooner).

Our Verdict

If you're looking for a professional gutter sealant that will last for the long haul, go with Geocel 2320. It's the industry standard for a reason. It's UV-resistant, paintable, self-leveling, and perfect for long-lasting leak-proof gutters.

How We Chose the Best Gutter Sealants

To find the best gutter sealants, we focused on what the professions actually use.

At most big box stores, like Home Depot or Lowes, we have found they do not have the best options for gutter sealant

If you want long-lasting gutters, you should use what the pros use. These options are affordable, easy to use, and will last a long time in-between repairs.

You may need to order them online instead of going to the store, but they work wonders

We have also found that rubber based sealants are by far the best. If you already have sealant on hand already, make sure it is rubber based.

It’s a common mistake for DIYers to use silicone based sealants. They end up needing to repair their leaky gutters every year. Silicone is not recommended for gutters.

What to Consider When Choosing Gutter Sealant

sealed gutters that are leak proof

When choosing which gutter sealant to use, here is what you should look for.

There are a lot of factors to consider, but there are options out there that check every box.

Type

There are a wide variety of sealant types based on if they are water-based, oil-based, and more.

For standard aluminum gutters, it’s hard to beat rubber-based sealants.

They are resistant to the intense rays of the sun and are often paintable.

Other common sealant types for gutters include propietary blends made specifically for gutters.

Sealants such as Geocel 2320 are an example.

Silicone based sealan

Adhesion Strength and Surface

When applying the sealant, you want to make sure it’s compatible with the type of gutter that you have.

Most gutters nowadays are aluminum, especially in new constructions.

But for DIY projects, it’s common to use vinyl. This will have completely different bonding properties and you’ll need a different sealant.

Other gutter types include copper, steel, and cast iron depending on your location.

You always want to use a sealant that’s a good fit for the material of your gutters.

Otherwise, the sealant will wear away fast and you’ll need to do it all over again.

Dry Time, Flexibility, and Durability

Before beginning a gutter sealing project, you want to remove any old sealant with a wire brush. Otherwise, you will not have a strong seal.

Also make sure the area is dry and clean. Some types of sealants will say they can work in damp conditions, but for best results clean and dry is better.

Over time, your gutters will move as they get hit with heat and cold weather.

The heat will make them expand, while cold will make them shrink.

To keep your moving gutters sealed, you want a sealant that expands and shrinks with the gutters. Otherwise leaks will develop.

Certain types of sealant will last longer than others too. While silicone based sealants will last for a year, rubber sealants can last for decades.

Versatility

When looking for a gutter sealant, it is best to get products that are for gutters.

They are for gutters and nothing else. This means the specialized products will (usually) do a better job by staying leak free for longer.

At big box stores, you will find more general products made for a variety of uses. If you do find a general product, make sure it’s used for roofing jobs, such as shingles.

Sealants made for roofing tend to have better UV-resistance. So they are a good fit for gutters depending on the blend.

Make sure to also look at the shelf life. Nothing is worse than opening the bottle only to realize the entire contents are solid.

This can often happen with products that expire in 6 months or less.

Safety

When handling the sealant, always check ahead of time if it is toxic. Luckily, most of the options are not toxic if you get any on your skin, but some may be.

Always wear glasses to avoid any sealant in your eyes.

If your sealant is toxic, wear the appropriate safety items such as gloves if needed.

Tips for Using Gutter Sealant

gutters protecting foundation
Image from Canva

Now that you are ready for your gutter sealant project, let’s walk through some tips.

You’ll be learning exactly what the gutter pros do so you can have long-lasting gutters that won’t leak.

Here are some basic tips:

  • Clean gutters before applying: Before using the sealant, clean your gutters. You want to remove any leaves or debris that might be sitting in your gutters. Wipe out any mud or gunk around the joints you plan on sealing.
  • Remove old sealant: Use a wire brush or metal scraper to remove all the old sealant. Leaving the old sealant can ruin the seal and cause your gutters to leak. Even if you apply new sealant over it.
  • Dry the area: Always make sure the area is dry before applying the sealant. You will get a more water-proof seal. If your gutters are wet, either wait until they are dry or wipe off the area beforehand.
  • Check the weather: If you plan on applying the sealant, you want at least a day or two of sunny weather. Any rain can ruin the new sealant you install. If you plan on doing more than one coat, you may need an extra day for everything to dry.
  • Apply a generous bead: Place a large bead of sealant down. You want the entire crack full of sealant with some extra to settle into the crack. You also need extra so you can overlap over the edges of the gutters.
  • Flatten the edges of your bead: Go accross the sides of the sealant bead and flatten it down with your finger. You want the bead to be almost in the shape of a triangle. The flatten area around the bead will make sure no water can penetrate through the sealant.
  • Give at least 24 hours to dry: You want at least 24 hours of dry weather for the sealant to dry. If it begins to rain on your fresh sealant, you can expect leaks to develop.

Can I Use Silicone Sealant on Gutters?

Silicone sealant is not recommended for gutters.

It does not last as long as rubber sealants and is not as UV-resistant.

You can use silicone sealant if it’s an emergency, but it will not last very long (usually under a year).

Can I Use Flex Seal as a Gutter Sealant?

Flex seal is not recommended. Often used by DIYers due to its availiability, Flex Seal is not recommended for gutters.

Flex Seal is a silicone based sealant and will not last as long as a rubber sealants or other propietary blends.

How Long Does it Take for Gutter Sealant to Dry?

Gutter sealant can take 2-24 hours to dry depending on the sealant you use.

Always read the instructions on the back of the container for optimal drying time.

If you plan on applying more than one coat, it can take several days to finish the project.

Always plan ahead and check the weather when applying sealant to your gutters.

How Long Does Gutter Sealant Last?

Gutter sealant can last up to 25-35 years depending on the type of sealant used and the weather in your area.

In certain cases, gutter sealant can even last up to 50 years.

When a poor sealant gets used, it can develop leaks fast. Silicone sealants are notorious for not lasting very long on gutters.

How to Remove Old Gutter Sealant

It’s always recommended to remove old gutter sealant before applying new sealant.

You can remove old sealant with a wire brush. Scrub the old sealant until it is all removed, making sure clean out inside the joint.

If you have an electric screwdriver you can buy a wire brush attachment to speed up this process.

Once the old sealant gets removed, wipe the area clean before applying the new sealant.

How Long After Rain Can You Put Sealant on Gutters?

It’s a good idea to wait at least 48 hours after rain to put sealant on your gutters.

If you have clogged gutters, you will need to clean them out and unclog them before the area can dry.

If you notice your gutters are still damp after 48 hours, wipe the area down around the joint. Once dry, you can apply the sealant.

How To Remove Gutter Sealant from Hands

Using sealant can be a messy project and if you are not using gloves it is easy to get on your hands.

To remove gutter sealant from your hands, start by rubbing your hands together. This will remove any large chunks.

Then apply acetone or nail polish remover to the areas where the sealant is still sticking.

The acetone will soften the areas of sealant so you can remove it with a cloth.

Once the sealant gets wiped off, wash your hands off with soapy water to get them squeaky clean.

Note: Always check beforehand to see if your sealant is toxic or not. If it is toxic, handle your sealant with gloves.

Scroll to Top