Cut a slit in any carpeting covering existing stairs using a utility knife. Make the cut in the top stair.
Remove the carpeting by placing your fingers into the slit and ripping the carpet from the stairs.
Remove any nails or staples protruding from the surface of the stairs with a hammer.
Sweep the stairs to remove any dust or debris trapped by the carpet.
Measure the distance of the overhang on each stair deck by placing a tape measure against the riser and measuring out. The overhang consists of the horizontal distance between the protruding lip of the top of a stair and the vertical riser beneath the stair.
Measure a distance equal to the overhang on the top of each stair deck using a tape measure. Draw a straight line across the width of the stair at this point, using a pencil.
Cut along the line drawn on each stair deck using a circular saw. Tap the edge of each stair gently with a hammer to remove the overhang cut with the circular saw.
Remove any extra overhang not removed by the saw and hammer with a hammer and chisel. Place the chisel at the edge of the remaining wood, and hit the chisel handle with the hammer.
Sand the area exposed by each cut.
Sweep the stairs again to remove sawdust created by cutting and sawing the stairs.
Measure the depth of the bottom stair, using a tape measure.
Measure the depth of the bottom stair on a stair tread, starting from the lip of the treading and moving the tape measure back. Add 1 inch to the depth of the stair. For instance, measure 9 inches back on the tread for an 8-inch-deep stair. Draw a line across the width of the stair at this point, using a pencil.
Cut along the pencil line on the stair tread with a circular saw.
Measure the width of the bottom stair with a stair measuring tool. Stair measuring tools contain two feet that slide along a central measuring mechanism. Open the tool on the stair by sliding the feet out until they reach the edge of the stairs.
Move the stair measuring tool to the stair tread cut to depth of the first stair, without changing the settings on the tool. Draw a pencil line across the depth of the tread on the outside edge of each side of the stair measuring tool.
Cut along the lines drawn on the stair tread with a circular saw.
Place the stair tread on the bottom step to ensure it fits properly. Use a saw to resize the tread if it's too big, or cut a new tread to size if it's too small.
Apply construction adhesive to the bottom stair deck. Use at least half a tube of adhesive for each tread.
Place the tread on top of the adhesive, lining it up evenly on the top of the stair deck.
Attach the stair tread to the deck by driving a finishing nail through each corner of the tread, using a finishing nailer.
Repeat the installation process for each stair in the staircase.