Backer Rod

Pest Proofinggap fillerEco-Friendly

Flexible foam rope used to fill deep or wide gaps before caulking. Provides backing for sealant, reducing amount of caulk needed and improving seal performance.

Typical Cost
$0.25-1.50 per linear foot depending on diameter
Shelf Life
Indefinite - does not degrade in packaging
Where to Buy
Hardware stores, home improvement centers, construction supply

Common Use Cases

  • Fill gaps larger than 1/4 inch before caulking
  • Back sealant in expansion joints
  • Fill deep cracks in foundation
  • Support sealant in pipe penetrations
  • Fill gaps between cabinet and wall

Application Instructions

Select backer rod diameter slightly larger than gap width (should compress 25%). Push rod into gap using flat tool or finger - do not stretch. Rod should sit 1/4" to 3/8" below surface. Apply sealant over backer rod. Do not use where it will be exposed to solvents or extreme heat.

Specifications

Closed-cell or open-cell polyethylene foam. Closed-cell for areas exposed to moisture. Diameters: 1/4", 3/8", 1/2", 5/8", 3/4", 1". Gray or white color. Sold by linear foot or in coils.

Related Materials

Other gap filler materials

View all

Copper Mesh

Tightly woven copper or stainless steel mesh used to fill holes and gaps around pipes, in walls, and other openings. Rodents cannot chew through copper or stainless steel mesh.

$8-20 per pound (covers many applications)

Steel Wool (Soapless)

PROFESSIONAL NOTE: Copper mesh is strongly preferred over steel wool for all rodent exclusion work because steel wool rusts and fails, especially in moisture-prone areas. Steel wool may be used for temporary exclusion in dry interior locations only. Must be soapless to avoid deterioration.

$3-8 per package
Important Disclaimer: The information provided in this knowledge base is for educational and reference purposes only. Pest management professionals should always consult current product labels, Safety Data Sheets (SDS), manufacturer instructions, and applicable local, state, and federal regulations as the definitive source of truth. Product formulations, application methods, safety requirements, and regulations may change over time. This information may be out of date and should not replace professional judgment, proper training, or required licensing and certifications.