I recently got a liner installed in my dirt crawl space to have the
soil sealed off from the rest of the house (mainly to keep moisture
away from the rest of the house).

Now, the installer installed the liner in a fashion that there are
still spots where it doesn't seal off the dirt from the crawl space
(i.e. I can pull back the liner in some areas and touch the dirt). My
question to you guys is whether such a liner installation can still be
considered effective with respect to keeping moisture from the soil
away from the rest of the house? Or does it have to be perfectly
sealed off to be effective?

Thanks a lot in advance,
Wilko