A threshold sits on the floor at a door opening and closes the gap between the floor and the door. This keeps drafts, moisture and insects from entering your home under the door. When something damages the threshold, it needs to be replaced as soon as possible. Install a threshold to a concrete floor in much the same way as you would to a wood floor. This project requires no special techniques, but it does use a few different tools.
Measure the door opening's width. If the opening has a threshold installed already, measure the old threshold's length and width. Tighten a Phillips driver bit into a drill and back out the screws securing the threshold to the concrete floor.
Use a utility knife to cut through any caulk securing the old threshold to the concrete floor. Insert a pry bar between the threshold and the floor. Pull down on the pry bar's handle to lift the threshold off the floor.
Hold the old threshold on top of the new threshold. Trace the old threshold's edges to transfer the contours to the new threshold. If no old threshold exists, measure the door jamb stops -- the thin strip of wood running up the side jambs' centre -- and transfer this to the new threshold.
Cut the new threshold with a jigsaw. Lay the threshold in the opening and check that it fits tightly against the side jambs. Tighten a 1/8-inch masonry bit in a drill. Drill a pilot hole into the concrete floor through each of the threshold's screw holes.
Use concrete screws to secure the threshold in place. If you want to use the screws supplied with your threshold, you need to use anchors. Drill the pilot holes with a drill bit the same diameter as the anchors. Tap an anchor into each pilot hole with a hammer and then secure the threshold in place.