We're working w/an unfinished basement staircase (what the contractor installed). We planned to simply pry up the existing bullnosed, solid treads and replace them w/solid pine treads, HOWEVER, we discovered the (closed tread) staircase has a mortised stringer. Our questions are:

1. If we pry/saw out the current tread (from the mortised situation) will it compromise the stability of the entire staircase?

2. Since we wont be able to fit the new tread back into the routed/mortised slots, can we just nail the new tread onto the middle & end wedges (leaving the routed/mortised slots unfilled)? If so, will this make for a stable staircase?

I've been searching your site all day and can't find an answer to these questions. I appreciate your resonse(s).

jenise

Sounds like you have a mortised sideskirt. The stringers are what you call wedges. Assuming your stringers are solidly mounted, you can attach your treads directly to them.
Is it possible to cut the bullnose on the existing treads and lay your new treads on top? This is sometimes desirable if your rise variance is within limts(and you plan on new risers). If not, removing 2-3 treads and shimming can even it out..