Everyone else is right. But 2'' is also a bit excessive, and is
probably due to the nature of your foundation and a remarkably thick
door frame threshold -- if the floor is resting directly on a concrete
slab, and is say only 1" thick, then the bottom piece of the door frame
would have to sit above the slab (and so must be about 3" or more
thick, which seems like a lot). More likely, the door is sitting on top
of the same subfloor that the wood floor is sitting on, giving you only
about 1/2" pocket to set the treshold in -- which is normally plenty.

Our doors have a threshold about 1" high at most, even our sliding
doors.

wrote:
Hi,

What you are seeing here http://i.math.drexel.edu/~pg/step.jpg is the
entrance into my hose from my porch. What you see is a concrete step,
then a wooden threshold about 2" high, and then the hardwood floor is
the same level as the top of the concrete step.

What is the purpose of the threshold?

(My initial idea was for water protection, but then I realized that the
porch is several feet above the ground and the concrete step is almost
a foot tall, so that can't be it. Could it be that the door was the
wrong height when it was originally bought?)

Thanks!

Aaron Fude