Hi all.
I'm planning to replace the entire door frame/side light
timbers in not too distant future. The frame that is
in place now is probably the same one installed when the house
was built about a hundred yeasrs ago, although the door was
new circa 15 years or more ago.
So if I'm going to replace the frame I should also replace the threshold
timber.
So 2 questions:

Is it a simple job the remove and replace the threshold?
..
And what kind of joint is it that locks the frame verticals to the
threshold?

Thanks.

Arthur