Re: Old Pine Floor
Yes, you should use a vapor barrier, 15 lb. felt will work. Second I would finish the boards on all sides and ends to help stabilize the wood. If it is not quarter sawn it is going to have a tendency to cup, sealing will help limit that.I prefer "Old Masters" oil based poly. It's a durable, hard finish and has great self leveling properties. Stay away from Minwax products, IMHO in recent years they have become crap.
Be sure you live your life, because you are a long time dead.-Scottish Proverb