HI all,

I have a couple of questions about redoing our interior stairs.

The house is 100 years old and the existing treads and risers are quite
worn and some of the tread nosing has been broken off. The risers and
treads are 3/4" pine boards. I have no problem replacing these, will
use 1 inch oak for the treads and most likely 3/4' poplar for the
risers. Will paint the risers and stain the treads to match the
hardwood floors.

The stairs are about 40" wide with two stringers made of 2 by 12 (true
2 inches thick and 12 inches wide) and one middle stringer made of 3/4
inch pine.

My concern is the span and the middle stringer; I would like to replace
the middle stringer with a thicker one as the stairs are a little
wobbly.

First is replacing the center stringer overkill? Or should I replace
this with a good piece of 2by lumber

The treads are on the narrow side (about 8 inches) I read in an old
construction book (circ 1940) that treads should not extend more than 1
3/4 inches beyond the riser. So to widen the steps a little I wanted
to have a 1 3/4 inch overhang on each tread. Is that too much for a 1
inch oak tread?

I tried to find out stringer spacing requirements on the web but no
luck, only thing I found is a rule of thumb of 32 inch span between
stringers. Any suggestions?

Thanks,
Dave M