Caulk Saver Foam Backer Rod for Gaps and Joints Backing Rod Concrete Filler Rope, Gray (3/8 Inch x 260 Ft)

I have a very tough situation with a west-facing penthouse facing the pacific. The siding rotted around the windows and I had to replace it and recaulk around the windows. I jammed this into the joint to back the caulk and it seems to work.

I should have bought the 1/4 diameter but I went with 3/8 inch. I also but way too much. I was able to get double the amount for less than 50% for the lesser amount, if that makes sense. I have way too much left. However, the product is easy to work with. Snip off the amount you want with scissors or tear it from the roll. I used a standard screwdriver to push it in the cracks between the window frame and the brick wall.

I had an enclosed porch that needed caulked but the paneling that was up left about an inch to the floor. Put this in and then called and at turned out perfectly.

As advertised

Lowered my radon significantly by simply plugging the cracks.

Does not work well for caulking base

It fills cracks