Degenerate
Even if you have a building, it will eventually turn back into dirt. Everything will degenerate eventually. A brick falls off here, a door comes loose there. Nothing can last forever.
Imagine a time lapse video of a building degenerating.
だ
お, くず
None
As you watch the building degenerate, you can't help but think of your dad (だ). You had to watch him waste away the same way of a degenerative disease. Why do people have to die, dad?
This may not be a happy thing to think about, but it will help you remember this kanji better. Imagine your dad fighting a degenerative disease. Imagine helping him fight through this. Everything will be okay eventually. I promise.