Caulking Tips: Use Backer Rod

The secret money saving tool with most any caulking job is backer rod.

Insert backer rod for best caulk performance. Insert backer rod to create best joint design and save money on caulk.

It can go by many names: pre-caulking filler rope, Grip Strip, backer foam. What is backer rod, and how in the world does it help you save money? Read on to learn!

Insert it into all caulk joints that are 1/4" wide and 1/2" deep or larger.


1) It fills the joint so you use less caulk (read: saves you $$$); and

Caulk stretches better and lasts longer with backer rod. Caulk stretches better and lasts longer with backer rod.

2) It creates the ideal joint design, allowing the caulk to stretch properly so it won't rip or tear, which helps you avoid re-doing the work (read: saves you $$$ AND time).

What types of backer rod are there, and where do I use them?

Sashco's Filler Rope™(shown in picture above):

  • Great for indoor and outdoor use in joints up to 1 1/4" wide.
  • Water-resistant outer skin, but also very pliable for easy insertion into tight joints.
  • Light gray color.

Closed cell round:

  • Most common type of backer rod, widely available in most any hardware store.
  • Great for indoor and outdoor joints
  • Water resistant
  • More stiff than Filler Rope™. Not as pliable for tight-fit joints.
  • Usually gray or black in color.

Grip Strip:

  • Closed cell trapezoid shape
  • Great for indoor and outdoor use
  • Best used in between slab siding or in wide chinking joints on log homes
  • White in color.
  • Can be cut down to size in order to fit a joint

Open cell round:

  • Good for indoor use only.
  • Most pliable of the backer rods so great for tight joints
  • Usually yellow in color