EXPANDER Nails Expander nails are designed for light and continuous installation of brick, concrete and natural stone. Applications include the installation of steel and timber cavities in concrete, in the underside of concrete floors or for nailing battens to suspended ceilings. The expander nail is tubular and compresses slightly when driven into a pre-drilled hole. The tendency of the steel to return to its original shape causes the nail to be clamped in the hole. Expansion is parallel along the entire length of the nail, providing a large contact area with the substrate for a secure fastening. When drilling, the hole diameter should be the same as the nail diameter.