Thresholds are used at the bottom of door frames at home entrances. They are also used in interior doorways or pass-throughs where the flooring transitions between rooms. Floor thresholds, as these are called, are installed in the same manner as exterior door thresholds, except they don't need to be sealed with caulking on the front and back edges. They are installed on interior doorways when there is a carpet-to-wood or wood-to-tile flooring transition. The threshold helps protect the flooring at the edges and creates a more finished transition between rooms.
Measure the opening along the floor inside the interior doorway or pass-through. This is the length required for the threshold. Measure the thickness of the wall at the doorway opening. This is the width required for the threshold. Thresholds come in standard widths to accommodate different standard wall thicknesses. Assess the two adjoining floors. If they are level, you can use a flat-bottomed threshold. If one floor is raised above the other, you will need to use a rebated (notched) threshold. This will accommodate the raised floor.
Lay the threshold flat on a work surface with the top facing up. Measure the threshold and mark it to the length of the measurement in Step 1, using a pencil.
Place the threshold on the table of a mitre saw with the top facing up. Slide the threshold along the mitre saw table and align the outside of the pencil mark with the edge of the saw blade. Pull the trigger on the saw and guide it down through the threshold until it is completely cut.
Position the threshold across the floor in the doorway opening so that it's covering the seams of the adjoining flooring materials. Orient the threshold so that the rebated (notched side) is covering over the higher floor if the adjoining floors are uneven. No floor-surface preparation is needed to install an interior threshold.
Drill 1/16-inch-diameter pilot holes through the centre of the threshold every 6 to 8 inches along the entire length. Drill through the threshold and into the floor approximately 1/2 inch.
Drive the included screws through the mounting holes that you drilled in Step 5 and into the floor, using a screw gun, to fasten the threshold in place.
Select a threshold in a style that will complement your flooring and existing woodwork.
Wear eye protection when installing thresholds.