On Mon, 8 Feb 2010 04:26:30 -0800 (PST), the infamous Sonny
scrawled the following:

From what you have described, plaster and lathe, I wouldn't think the
plaster and lathe is along the bottom of the stair stringers, but

C'mon, guys. A lathe is a roundyround tool. Lath is a stick used in
construction.


encases some cavity under the stairs. Since you will open that area,
why not finish the interior, there, for storage or other and create an
access door, concealed, maybe, if an obvious door would not complement
the surounding design/decor/trim.

I second the additional storage suggestion.


If there is such an area, accessing a tread should not be an issue, in
order to secure the tread easily.

For the fix, I'd glue and screw a board to the bottom of the cracked
tread. I'd fastening the board to the front riser under the tread
with a screw, and to the back of the next riser via another board
coming down, also glued.

--
We don't receive wisdom; we must discover it for ourselves
after a journey that no one can take for us or spare us.
-- Marcel Proust