Exterior door thresholds help keep wind, water and insects from entering your home. Thresholds are especially important on ground level doors exposed to storm runoff and snow accumulation. A tight seal will help keep any water or snowmelt outside of your home. If your ground-level floors are concrete, you'll need to mount the threshold directly to the concrete slab. With a hammer drill and some concrete screws, you can install an exterior door threshold on a concrete slab floor in just a few minutes.
Measure the width of the doorway with a tape measure. Cut the threshold to fit snugly into the doorway. Notch the ends of the doorway to fit around the jamb stops, if necessary.
Place the threshold in the doorway in its final resting position. Close the door and make sure the door fits snugly against the threshold. Mark through the mounting holes in the threshold onto the concrete with a pencil. Remove the threshold.
Slide a concrete screw through one of the mounting holes in the threshold. Measure the length of the exposed screw on the underside of the threshold. Add 1/4 inch to the measurement and mark that length on a masonry bit with a piece of tape. Drill the mounting holes in the concrete slab with a hammer drill and masonry bit. Drill straight into the concrete, using even pressure, until the tape touches the slab. Vacuum the mounting holes and doorway to remove concrete dust.
Sweep the concrete in the doorway and wipe it with a damp cloth to remove any dust or dirt that could prevent the sealant from bonding to the concrete.
Apply silicon sealant to the bottom of the threshold in the locations indicated in the instructions. If the threshold has rubber or silicon gaskets installed on the bottom, skip this step.
Place the threshold in the doorway and press it down into place. Insert concrete screws in the mounting holes and tighten them with a screwdriver.