Then build firewalls between properties and businesses.

Some do well with it, others need to set up fire walls so they can focus and not be forced multitask.

I even dumped a few bags in the fire wall space between units in the attic.

“The way my realtor and I typically work is he knows I just want to hear numbers.”Do you believe this sets up some sort of firewall between you and you borrowers?

When they build them they need to make sure they build fire walls between units that go all the way to the roof.

Rehabbed and flipped it.Took it down to the studs, and then called in the Building Dept Inspector, and told him our plans.He agreed with everything that we wanted to do.As the work progressed, we had him come over to take a look, and he said, everything that we had done, was exactly the way he would have done it.We had to build a fire wall in the basement, because the garage was part of the basement.We thought that we had to put in a solid metal door, and he told us, that a solid wood door is legal.

There is also a brick parapet running through the middle that acts as a firewall between the four units (it is a quadplex).

I have been told that mice can still come from the other homes connected to mine, via bitting through the firewall, and make entry again. 

That is annoying.We have a great firewall here!

@Megan Clancy The answer is reasonable firewalls between sets of assets, and plenty of insurance.