The issue of whether to run the crawl space vapor barrier all the way up the crawl space foundation walls has been discussed form time to time;

As modified from points Andy raised in the last discussion on this, I generally oppose running it up to the sill plate unless there is a lot of exposed foundation material on the exterior to allow “rising damp” to evaporate off.

Here’s a pic from a crawl space today: 40 year old house; brick veneer; sill plate probably about 6-8″ above grade; and VB and FG batts recently added (within the last year, at a guess.)

It doesn’t come through completely in this reduced size image, but the sill plate was soaked through – look at the “sticking plastic” to the left of the piece I tore away, and the wood immediately to the right was glistening with moisture.

(There was a lot of condensation on the rim joist in this crawl, as well, but I believe the soaked sill palate was from rising damp, not the condensation.) View Image

Another reason I don’t like VB up the crawl wall is that it makes it harder to spot termite tubes. This pic is from the back of the same crawl. The arrow on the left points to some tubes on the bare wood. The arrrow on the right points to some tube material behind the plastic. (In this case, the plastic was probably put up after the termite tubes were formed and I suspect the home owner might have been trying to hide termite evidence, but the concern remains the same.) View Image