Carpet on stairs in a home or office eventually wears down and becomes compacted and ugly from unavoidable traffic. Worn carpet can be covered--and prevented--by installing stair runner rugs on top of the carpeting. A runner rug is a full-length additional carpeting piece placed along both the rise and tread of each stair step. Tread rugs can be placed on individual step tops and provide the same coverage as stair runners.
Vacuum the stair carpet before installing the runner. Use different brush attachments to extract deep dirt.
Measure for the length and width of the stairs. Find the exact middle of the stair width and mark it with a small chalk mark. Determine how much space to leave on the edges of the runner; you should have an equal measurement between the installed runner and the wall, and between the runner and the other wall or railing. Draw lines on both the rise and treads of the stairs to mark where the ends of the carpet should lay. To find the length needed for the runner, begin at the top step and measure the tread and rise for each step, and where you wish to place the runner.
Cut tackless strips to place at the back of the treads and at the bottom of each rise. The tackless strips secure the runner into place without placing tacks in the middle of the runner, where they can wear spots in the rug or cause minor bare feet injuries. The tackless strips should be roughly 1½ inches narrower than the width of the runner.
Attach the tackless strip to the back of the tread and bottom of the rise. Hammer the tackless strip onto the stairs using finishing nails that are long enough to penetrate through the existing carpet and pad and into the wood of the stairs. The strips should be positioned approximately an inch from the back of the tread and an inch from the bottom of the rise. Different installers may recommend different measurements that are often based on the thickness of the runner you're installing.
Position the runner so the pile of the runner faces down the stairs; this is not vital, but will help you keep the stairs cleaner. After positioning the rug, place the runner over the stairs and begin installation, working from top to bottom.
Drive carpet tacks into the top edge of the carpet, then pull the runner taut down to the tackless strip on the rise, curving minimally at the corner and placing the carpet over the tackless strip on the tread. Attach carpet nails every 6 inches along the inner edge of the runner to secure the edges into place before repeating this step on the remaining stairs.
Apply floor trim to secure the end of the rug. The runner should end either at the bottom of the last rise, on the floor past the final rise, or at the end of the final tread. The runner should never end in the middle of the final rise.