Should Zombies avoid fire?

I’ve been playing with matches, and I’ve found that the pile of wood a door gives you is enough to make a lethal fire, but not enough to cause it to spread. In practice, this makes deals with a hoard really simple, just lure them to a broken doorway, and a few turns before the first zed enters, light the pile. They all step in one at a time and burn up.

Unfortunately, I just lost my base by doing the same thing to a cleared out broken window with a stick on it, and the fire engulfed the entire house. Oops. I just don’t know what went wrong.

Anyway, this technique seems way too powerful, easily cleaning out a dozen zeds at a time if you’re careful. I think this should be nerfed. A burning zed should have its inventory torched, but it should be able to survive long enough to step through the fire, especially if it’s a small seconds old one. Burning zombies inside your base (or any enclosed space for that matter) should make the threat larger, not smaller.

I think you hit quit before it all went bonkers.
Just browse Cataclysm DDA wiki a bit, or this forum and you’ll find that it’s easier to get yourself killed when using fire other than staying clear of making one. Anything you do can cause more trouble than you expected; if you liked those explosions, well, soon you will find out your surroundings likes it more. >:-)
As for mindlessness of Zs is concerned, not all of them, and not always, will they step upon that square that you just lit.