The problem with plywood is getting in from here to there. It's heavy and getting a good grip is difficult...especially if you have to carry it for any length of time. An easy solution is to take a couple of C-clamps and tighten them on to each end. This will give you the handle you need to get a good, solid grip.
When buying a house, be sure to change the locks immediately. There is no telling how many people had access to the previous owner’s keys. When renting, be sure to ask about the landlord’s key-control policies.