Should I add builder's felt when replacing clapboards on old house?

[blueman]

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

[marson]

[hallerb]

i would prime the wood behind to protect it a little