George wrote:
Our house (c 1920?) has a split tread on a built-in staircase.
Questions:

* I can pretty easily rmv the ceiling underneath. I'm considering just
cleating some sort of backer behind it, and leaving the existing
(damaged) tread in place. Any thoughts on this?

* If I do replace the tread, when sort of wood should be used?

Thanks,
George

I would glue and screw as you seem to be suggesting, try to clean out
any debris in crack to get a nice tight fit. Then use wood putty on
top if needed, sand lightly, stain, etc. I think this will be easier
than trying to match the appearance with a new piece. If you do decide
to replace, bring the split piece to lumber yard. Trouble is, lumber
available today may not match that from 1920.