We saw the percolation test, and I'm not a soils or plumbing engineer by any means, so I cannot really weigh in helpfully on that subject (of getting a septic/sewage system installed). 

If there's original wood plank flooring underneath a carpet that's trashed, then a light refinishing can be affordable, even if it's got some blemishes which just contribute to its "character". 

The end result is that the vast majority of the walls/ceilings are falling apart and some even have mold underneath. 

Typically the home is then excavated out underneath to allow for your new basement pour.

Which is reprehensible.In Cleveland, my understanding (and yes, I’ve been keeping up with the reports on this issue) is that the vast majority of the problem is from lead paint in older homes and lead in the soil of former commercial properties.

I have read that soil quality effects the life span of the foundation but have not yet done any additional research.

I did it on my personal house, it's a couple hundred bucks for soil delivered by truck (yards of soil, not a bag from menards) and some gutter extensions if it's really wet.  

Daniel, what oftens happens is that they change the carpet and never change the padding underneath.

do you have snow.. freeze thaw.. or in spring when things grow wild  LOL  or texas were your soils move and create foundation issues over time .. or in Vegas were you have no yards  but sun beats the crap out of the places LOL.. how old is the house.. etc etc. 

The soil is unstable and many older homes do not have gutters.