Everything You Need To Know About Foam Backer Rods

Everything You Need To Know About Foam Backer Rods

Everything You Need To Know About Foam Backer Rods

Literally and figuratively, there is so much flexibility available with a foam backer rod. This handy item blocks out any unwanted moisture and streamlines many processes for construction workers. That is why it will be quite easy to find these foam rods on a construction site, as they provide so much versatility and ease. If you’ve never used them before, you might wonder if backer rods are waterproof and how to use backer rods for caulking. Keep reading if you are not entirely familiar with these helpful objects or wish to learn some useful information; here is everything you need to know about foam backer rods.

Foam Backer Rod

What are foam backer rods? You might be entirely unfamiliar with foam backer rods, but that’s okay—we will go in depth on the topic. These rods look like foam noodles that kids and adults alike love to play with and use in a pool. However, unless you accidentally shrink yourself down, foam backer rods probably won't do well holding you up in the water.

True to their name, foam backer rods are round tubes made of a spongy material that makes them very flexible and perfect for fitting into small, tight areas. Moreover, they come in a wide range of shapes and sizes, making them perfect for any job.

Why Use Them?

Did you know that foam backer rods were specifically designed to fill any joints or crevices before applying sealant? If you haven't heard of using a foam backer rod when caulking, you might assume there is really no point to them, but you would be wrong. Their waterproof, flexible, and malleable nature makes them supremely helpful for weatherproofing purposes, closing off gaps, preventing sealant from cracking, and improving the aesthetic appeal of your house.

Depending on the size, they are not always required, but they are extremely beneficial if you work on any renovation or construction project. It would help if you used a foam backer rod for any crack, gap, or joint larger than a one-quarter inch that needs filling. Without a rod, the caulking job could fail because there is too much space for the sealant to fill. Moreover, with a foam backer rod, your caulking job can withstand the test of time.

How It's Used

If you are doing construction work, there will always be a gap in the middle of any connection between materials and building elements. For example, say you are installing a door in a brick house—even with a perfect fit, you will need to seal off some cracks. This is where a foam backer rod comes in, as you will place it in the back of the gap before applying sealant.

The sole purpose of caulk is to close off the crack between the door and brick, not to fill in the back of the crack. If you use caulk to fill in the back, the sealant is more likely to crack or appear distorted. A foam backer rod takes the phrase "I've got your back" to a whole new level, as it fills up the back of a crack so the caulk can do its job.


Foam backer rods are extremely useful for caulking. The use of caulking is multidimensional; it can repair gaps, joints, and cracks in or around your house's exterior, its interior, and all surfaces. Caulking is extremely valuable, but to make the most of its use and ensure its longevity, you should consider using a foam backer rod. Many people don't use rods simply because they are unaware of their existence and caulk a joint without one. With a backer rod, you will be caulking like a pro!


You could be anywhere, not even actively surveying the construction of a building, and your eyes will stop upon it. It is the elephant in the room that you can't help but notice—poorly applied sealant! Nothing takes you out of the moment more than a lousy caulk job. You likely know the look: squiggly, uneven, and falling off.

It is incredible how a poorly applied sealant can drastically alter the look and appeal of a building. It gives the impression of a rushed job done with little to no attention or care to detail. However, a foam back rod applied before caulking can fix any issues in aesthetic appearance; this is especially important when you are caulking high-traffic areas.


There is nothing more frustrating than feeling a cool chill emanating from a window or door somewhere in your household. Cracks can occur due to normal wear and tear or improper sealant application. That is why most construction workers will use a foam backer rod, as it helps make an airtight and waterproof seal that caulking alone cannot efficiently and entirely do.

With proper weatherproofing applied to your household, air can't seep in or out as quickly. Foam backer rods will also help improve your stress, as you might see a significant improvement in your energy bill.

How To Choose

Now that you have received the rundown on everything you need to know about foam backer rods, you might wonder how to choose the right one for your job. These rods come in a relatively wide range of sizes and shapes; they’re available from about one-fourth of an inch to four inches in diameter. Moreover, they come in different shapes: open, closed, and bi-cellular. Foam noodles are also easy to cut down to size to adapt to uniquely shaped gaps and spaces.

Do you have a construction project coming up for which you need to find foam sheet rolls? If that is the case, then FoamNoodles is happy to help you secure the right fit!

Open Rod

Open rods are perfect for window glazing as well as any jobs dealing with expanding and contracting joints. Their open structure allows for more breathability, so air can easily pass through, allowing the sealant to dry quickly. However, they are not suitable for projects requiring weatherproofing due to their airiness. Moreover, they are very flexible and soft, making them easy to control and excellent for more minor, harder-to-reach gaps.

Closed Rod

Closed rods are dense and thick, making them quite impermeable. Closed rods are perfect for weatherproofing, as their thickness keeps moisture and air out and won't taint the sealant. Moreover, its dense structure makes it easier for caulk to stick to its surface—better than with an open rod—which is important for weatherproofing.

Bi-Cellular Rod

Bi-cellular rods have the best of both worlds; they have the softness and flexibility of an open rod with the density of a closed rod. The outer skin of a bi-cellular rod repels any moisture or dampness while its inner structure is very compressible. Bi-cellular rods are perfect for any job an open rod can do, especially if that area is in a place more prone to moisture, but you shouldn’t entirely rely on them for serious weatherproofing; in those instances, use closed rods.

Foam backer rods can be indispensable for construction projects. To learn more about how contractors can benefit from foam noodles, you should explore our blogs or contact us with questions.

Everything You Need To Know About Foam Backer Rods
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