I need to replace a couple of damaged clapboards on a 100+ year old
house.

The (original) sheathing is 1-by-X without any apparant builders felt
(or maybe it has just decayed over the years).

When replacing isolated clapboards (either single ones or at most 3-4
in a vertical row), should I add some type of vapor/weather barrier
behind the replacement clapboards?

If so, what would you use and how would you apply it?

Thanks