Originally Posted by jeh
but is it common to have so much poo in the joist space? is that not a health risk?
It's common if they've had access for years and it has accumulated. I would be more focused on denying them access in future than ripping out your walls to track down rat ****. That is the kind of thing that is a slippery slope. It could be everywhere, for all you know, as once they are in house it is relatively easy for them to travel around it through plumbing and heating and cooling chases.
No, it's not a health risk. It dries out and is basically just dessicated organic matter sitting up in a sealed area.
Of course, it might be a risk to your psychological health, knowing it is all there. That's a different matter.