Cover Stairs with Hardwood or Replace with New Stairs?

"I have ugly carpeted stairs, and I want the look of a nice hardwood custom made stair. Should I cover my existing stair with hardwood or replace with new stairs?"

First consider how old your existing stairs are. If you have fairly new pine stairs under your carpet, the moisture content in your pine lumber will be higher than it will be in the hardwood. The woods dry differently. When a wood with a higher moisture content is covered with a dryer wood, it creates a high probability that it will develop squeaks.

Fitting hardwood stair parts to an existing stair can be laborious. There are about 30 pieces in a basic stair alone. This will likely result in over 100 cuts from prepping to installation. Keep in mind it's harder to make a non-square cut to fit something existing than to make a good/new square cut.

The cost of buying the hardwood stair parts will be essentially the same as buying parts for a new stair. The main difference is the labor of fitting them onto an existing stair or building a new stair. There may not be a savings to cover existing vs. a new stair.

Last, but certainly not least is quality. A new custom built hardwood stair will likely have better joinery and fit. It allows you the opportunity to use new routed stringers and have your treads and risers tightly wedged into them. A method of measurably better construction.

Price out both methods and compare all facts to make an educated cost decision.