david blumberg wrote:

Alternate tread stairs are for steep applications, such as to a loft. I
was asked to build a set for someone. The tread width is 24", the depth
for the wide half is 10", reducing to 4" for the narrow half. Thickness
spec'd at 1 1/16". Housed in the stringers (1 1/2" thick). Material to
be ash, maple, or birch...

I wouldn't worry about the glue...I'd worry about the wood itself
snapping along the grain. This is probably why the one you linked to
used plywood.

I've seen a version of this where they had a third stringer down the
middle of the stair, and each stair was only 12" wide but staggered (ie.
no "narrow half").

Chris