Say you took my earlier advice and decided to hunker down and wait for the dead to rot out. One problem you have to face is cabin fever. There isn't going to be any TV in post zombie land, and the nights get long. All those post traumatic stress problems are going to start popping up with your people. What you need to do is find some make work projects to keep everyone busy. Now a roof top garden is nice, but not really satisfying so I suggest working on a simple pit trap.
First, make sure the area is fairly clear of the dead. They seem to move around if you aren't rattling the cages so its fairly likely you can find a day where they are somewhere else. Have one look out and at least two people with guns. Make sure you have a knotted rope handy so folks can get out of the pit quickly. If you have access to a back hoe that would be great, but since this is a more a make work project it actually works better with just a bunch of folks with shovels.
Start the pit in front of the main entrance, say about thirty feet away. The pit doesn't have to be too deep, I wouldn't go much more than eight feet really. Make sure to pack the soil on the side of your dwelling. Also be sure to post a warning of some sort. A bright bit of fabric would be enough. Wouldn't want to thin out any more survivors now.
When you get it to a good depth start putting sharp things in the bottom. My preference would be sharpened rebar. The point isn't that is going to kill a zombie. The chance of a zombie falling and getting a rebar through the head is at best 50/50. The point is that the zombie is going to get pierced somewhere and that will probably make it even less agile. Don't worry if it doesn't seem big enough at first. It's a work in progress. Say your goal is to completely surround your base, there's no hurry in reaching that goal. Always remember safety first.
As your pit gets used by zombies you will have to deal with clean up. Generally I'm not in favor of setting zombies on fire because it takes a bit for them to take enough damage from the fire and until then you have to deal with both zombies and fire at the same time. However, for the pit its a good way to clean up. Bring a little gas and a match and then step back and let nature do the work. After the smoke clears if you have some lime be sure to shovel a little into the pit. It will keep it from stinking up the place too much.
In no time at all your group of survivors will have an excellent little defense against the zombie hordes. They'll feel proud and have a sense of accomplishment, which will go a long way to help morale. It might even inspire some to create their own traps. You might, however, want to discourage traps involving explosives and/or gunpowder. Remember, safety first.