What is a foam backer rod?

Asked by: Christina Smith

What is a backer rod and what does it do? Backer rods are usually round, flexible lengths of foam that are used as a “backing” in joints or cracks to help control the amount of sealant/caulking used and create a back stop. Many sizes/diameters are available for optimal fitting to the size of the joint being sealed.

Is foam backer rod necessary?

If bubbling concerns are critical on a project, then the backer rod is required. These innovative, foam rods used during construction are essential and necessary to a project’s success based on these reasons.

How do you use a foam backer rod?

You force the rod into the gap with a putty knife. And push it down just below the surface.

Why do you need a backer rod?

Backer rods are used as a “backing” material to fill a void, joint, or crack in residential and commercial applications. The primary purpose of backer rods is to: Control the sealant thickness and amount needed to fill the joint. Force the sealant to the sidewalls to ensure contact and proper adhesion.

When should backer rod be used?

A backer rod is a cylindrical type of foam used to fill cracks and gaps between building materials. It is used in a wide range of applications including tiling, flooring, window paneling and stoneware among others.

What is the difference between the joint sealant and backer rod?

Closed Cell



This means the material will not wick moisture making it suitable for joints with a high presence of water or dampness. Sealants, caulking or other chinking materials will stick more easily to closed cell backer rods which have a better bonding surface area than an open cell product.

Can you use sand instead of backer rod?

You can fill with silica sand, play sand, or backer rod. Spray foam or backer rod works great for large vertical areas like steps pulling away from stoops, if spray foam is used wait until it sets up, cut off even, or a quarter-inch below concrete then it is ready for sealing.

Does backer rod absorb water?

It is chemically inert and will resist oil, gasoline and most other solvents. The material will not stain, absorb moisture, nor adhere to sealant materials and is non-exuding.

Do you need backer rod for laminate flooring?

Foam Backer Rod for Gaps Along Walls



You are encouraged to install PE Foam Backer in the gaps along the walls after installing the laminate flooring. This foam backer will provide enough give for the boards to expand without becoming deformed. It also serves the purpose of adding insulation and resistance to moisture.

How do you fill a large gap before caulking?

Using foam backer rod to fill a wide crack before caulking. One of the best ways to save energy in your home is by caulking any cracks around windows and doors. While caulk alone can be applied to narrow cracks, gaps wider than 1/4” should be filled with foam backer rod first.

How thick of a gap can you caulk?

A single bead of caulk can fill gaps up to 1/4 inch. If the gap is slightly larger than this, fill it with a bead of caulk deeper into the gap, but not flush with the surface. Wait until the caulk is completely cured before coming back to put a surface bead on.

Does backer rod stop drafts?

They provide additional insulation and increase the energy efficiency of your home. By blocking drafts, backer rods ensure that your windows do not permit outside air indoors.

Is backer rod good for insulation?

The benefits of Closed Cell Backer Rod are:



Added insulation and log protection. Reduced amount of caulking or chinking needed. Flexible and great for log spaces.

Does backer rod stop drafts?

They provide additional insulation and increase the energy efficiency of your home. By blocking drafts, backer rods ensure that your windows do not permit outside air indoors.

Does backer rod absorb water?

It is chemically inert and will resist oil, gasoline and most other solvents. The material will not stain, absorb moisture, nor adhere to sealant materials and is non-exuding.