Our Foam Backer Rod is used to fill in your expansion joints just below the caulking. You want to use the size that is just a little bigger than the width of the expansion joint. If you find that the expansion joint has uneven width, slice the backer rod into better fitting smaller widths, or purchase multiple sizes of backer rods. Measure your pool’s perimeter for the proper length, and be sure to purchase a little extra.
Do NOT use sand in your expansion joint! Sand does not allow compression the way foam can, and as your deck expands it will create damaging force on your pool beam, coping or tile.