Wood Requirment:

These are the amounts of wood required to build each building and vehicle. These are in values of 100s similar to the trees written shortly above. I do not know what ?? does. This may be the number of wood required to rest in front of a hut. Has not been tested, but the other values have.

Please Note: As you decrease or increase the wood, it changes the building in the game, not graphically but in the sense that a Firewarrior hut will sometimes have extra wood taken inside and it's overall appearance goes unchanged, but the upgrade has been made.
Also Note: Decreasing the Amount of Wood on a hut's upgrades will weaken the upgraded states. If the 3rd level hut needs 1 wood, not only will the fully upgraded hut only have 1 wood for defense but it'll be instantly destroyed without time to repair AND the hut will automatically upgrade (aka change appearance) without use of wood because a normal upgrade gives you 1 of 3 wood. This is hugely important.