How to Design Flooring Thresholds

Measure the width of the doorway with a tape measure at the floor level. Determine a width for a threshold, from the outside of the closed door to the inside; thresholds may be flush with the outside edge of the door or extend beyond it. Measure the difference in height of the flooring if applicable; tile, for instance, may be higher than hardwood flooring.

Match a wood threshold to the flooring on a wood floor. Use oak, for instance, on a typical oak hardwood floor, of the same color as the finished floor. Use metal or vinyl for a carpet, ceramic or vinyl floor covering or fabricated thresholding for a laminate floor. Make the threshold conform to the use of the doorway; a kitchen or back door, for example, typically needs a metal threshold, while a front door requires something more decorative, compatible with hardwood or carpet.

Round or bevel the threshold's edges so there are no sharp angles to trip over. Bevel both sides for a threshold over level flooring surfaces. Indent one bottom side of a threshold to join materials of different height, so one part of the threshold is thinner to accommodate a thicker flooring material.

Create double thresholds for exterior doors with a storm door. Make a wood threshold for the interior part of the doorway, where the basic door will close, but use a metal threshold strip under a storm door. Butt those pieces tightly together, with the top surfaces level. Use this combination so the wood threshold does not extend into the area covered by the storm door. The metal threshold will conform to a metal door and weatherproof the wood threshold.