Upgrading to oak stairs is easier and less expensive these days due to the availability of oak stair treads. The stair treads consist of a 1-inch thickness of oak, risers (the rise between each step) and stringers (the boards that hold each step in place) from ¼ inch of plywood with oak veneer. Screws and glue are used to make the structure sound. You will need to measure your steps, risers and stringer and cut the oak to the dimensions that you need with a power saw, or have your building supply store do this for you. Number each step and riser so you know specifically where to install each piece. Installing an oak staircase with stair treads can be half the cost of installation with solid oak. This is a project that can be completed without hiring a carpenter.
Remove the nosing on the subfloor (the lip on the front of the step). Use a chisel, handsaw or power saw to cut it away from each step.
Cover the stringer (the side of the steps) with the ¼-inch oak veneer you had cut for the stringer. Affix it with construction adhesive.
Cover the riser of each step with the oak veneer that you previously measured and cut to size. Glue the riser in place with the construction adhesive and hammer in a few 2 ½-inch spiral finishing nails to secure it.
Install each of the treads by applying construction glue on the back and affixing to the tread. Hammer in finishing nails to hold it in place.
Fill any nail holes with a putty stick that matches the colour of the oak.
Always follow the manufacturer's instructions for specific brands of stair treads.
Wear safety goggles whenever using a power saw. Wear work gloves to protect your hands from scrapes or cuts.