I am trying to install hardwood treads and risers on my existing prefabricated stairs, and I have encountered a problem with the stair risers being different heights. I've read several articles stating that riser height should be within 3/8" of each other, and all under 8 1/4". Unfortunately the riser height at my bottom step will be 8 3/4" when I've finished putting on the hardwood tread. The top riser will also be much shorter than all the others. Is there a way to correct this? I'm most concerned about the bottom step being too high. The existing stair treads are pine that is mortised into the stringers. Could I just rip off the pine tread? Or will I make my staircase structurally unsound? Help, please.

I have encountered a similar situation with oak stairs. You can see pictures in the gallery of my lower staircase. It was the upper staircase that had me worried.

That is, until I looked closer.

Interestingly, the riser at the bottom was already taller than the remainder and the top riser was shorter. This was not a problem that I created, nor one that I was going to make all that much worse. Well, I am raising the floor riser by 3/4", but the top will rise equally to match the second floor wood flooring.

I wonder if these prefabricated stairs were intentionally made this way to match flooring on each level. Whatever the case, I'm not all that concerned.

Concerning the nosing and mortise, nail a fence strip on each tread to run your circular saw along. If you have a saber saw, cut even closer to the stringer. If you are really fortunate, the two saws will be the same brand and have the same width tables (Skil, for instance).

I cut carefully through the stairnose with a saber saw on each side of the nosing along the stringer, stopping just as the blade touched the riser. This provides an easy means to strike a line along the tread.

Use a short wonder bar to chop the remaining nosing out of the stringer.

Chop a 1/4" piece of nosing to fill in the mortise hole. Use spackling to fill the hole flush, sand an paint. You will never know the mortise was there!