The average cost to repair or replace stairs is $1,000 to $2,000, including materials and labor. Staircase repair costs are influenced by design complexity, material choice, labor rates, and stair shape. Common stair repairs include painting, carpeting, and structural improvement with specific material types.

The cost to remodel a staircase can range anywhere from $250 to $30,000, depending on the type of remodel. But most homeowners will pay around $1,500. Meanwhile, replacing a staircase usually costs between $1,000 and $10,000, with an average cost of around $2,300.

Simply cut the rotted or termite damaged materials out of the stair stringer and replace it with new lumber, possibly treated lumber if you think that will work better.

To tackle the old one, you can remove paint, sand down each step including the riser and stringer and refinish as you choose. But it takes a huge amount of time, especially if the treads are worn down. The next approach is to buy new treads and riser covers and new bull noses.