They pay your to rent space on top of the soil while owning their home.

I look underneath and sure enough it's cracked and water is running out.  

Going to build an ADU (800 total square feet) next to a house that has a basement and a second floor.Question is, which costs more:1) Building a second floor (roughly 400 sqft foundation and 400 sqft second floor).Or2) Build a basement (roughly 400 and 400 again).I realize there are many factors (sewer slope in basement, soil removal, etc.), I was just curious about general cost (2nd floor wood vs basement concrete).Any thoughts on the matter are greatly appreciated!

IN our market in the NW we have very few slabs and pretty stable soils  so to have a foundation issue is going to be a very old house.  

Includes 1 parking space, grocery store underneath building (great perk) and storage space. 1800/month rent and tenant is good till 2021 lease.

Since the sprinkler system runs throughout the soil in the garden wall and the soil is also basically a moderately inclined "hill", it might not be too easy to demolish the part of the wall that surrounds the ADU and fence it off, but my friend is fairly new to the rehab process.Here is a link to a diagram that explains it visually: ADU diagram (for some reason picture attachment isn't working)

Fees are typically very high because DSTs are relatively complex vehicles perhaps not that well suited for the uninitiated.They are a neat idea in principle, but they are very real issues underneath when you go to put things into practice.

I just purchased a house in Chicago and underneath the carpeting there was that old linoleum tile.

Put a plastic trash bag on the floor underneath it, and then hose the coil down well with your favorite multi-purpose cleaner (Windex, 409, Fantastik, Spic n Span, or equal), and maybe use a sponge or a wad of paper towels, gently, to wipe it down. 

Your architectural plan creation timeline varies greatly with the locale, municipality, architect's/engineer's workload & expertise, lot size, site utilities, soil conditions, age of current home, etc...