| Thanks Snag one, appreciate it, but let me ask this - are builders cutting
| these doors down from 24 inches wide, to something less (in my case 23 5/8
| inches)? My guess is no they are not.


I'm afraid your guess is wrong. It's just as Terry
Coombs said. Doors typically come in sizes at every
two inches. Even hollow core doors can be trimmed
a bit for height and width. They generally have
wood around the outside. A door replacing an existing
door often has to be trimmed, especially in old houses
where one side of the door frame can be 1/2" higher
than the other side.

The typical way to get doors is by ordering through
a local lumber yard for items in the Brosco catalogue,
which is a supplier that will deliver stock items to lumber
yards within 2-3 days. (Home Depot actually has
better selection at better prices, but it takes *weeks*
to get anything through them.)
If you can find a Brosco catalogue you can see the
way doors are typically sold. The options depend on
the door, but the typical option is 24, 26, 28, 30, 32, 34,
or 36" wide and 78 or 80" high.

You don't need a table saw to make a good cut. Just
clamp a straight edge onto the door as a guide and you
can cut it with a circular saw.

What you have, hollow core 6-panel, is almost certainly
masonite (junk, but they look pretty good... until someone
kicks a hole through them) that came pre-hung. If it's
23 3/4" that's probably a 24" door, but you're not likely to
find the exact same thing sitting around a lumber yard or
in a Brosco catalogue. Your options are to buy a stock
24" wood panel door or find a place to order a masonite
panel door. In either case, expect to do some trimming
to fit, and unless you find exactly the same brand you
may have to settle for slightly different panels. (Wood,
for instance, will probably have more relief than the
masonite version.) If you can find the brand and exact model
you might be able to order a 24" replacement at Home Depot.
You may or may not be able to get just the "slab". (Not
prehung.)