Zombie Panic! Source is a standalone cooperative, survival-horror, first-person-shooter! Set in the middle of a zombie apocalypse, players start as a small group of survivors attempting to stay alive. Each map will have its own objectives to complete and win the round or survive by a period of time.
The boards themselves have been converted into ammo that the hammer uses in order to enter "tool mode" to barricade. The boards can be dropped and picked up, just like any other ammo. When you don't have any boards, then the hammer can only be used as a melee weapon.
At the moment you can carry a maximum of 6 boards, just like you could when they were only a weapon. The only difference being you can use all of the boards from one hammer. However, 6 boards will likely be unbalanced and end up getting changed, this is just a starting point for internal testing.