The main stack, drain lines in the basement floor, trap and the sewer line to the city main are the big ones.You can either knock these out as they become problems or bite the bullet and spend the money.

Can you help a flipper with flooring?

The house rents for $1200 month currently and will be able to get $1600 if renovated (finish basement bathroom, new flooring and fixtures, mainly cosmetic).

My condo sits on the second floor.

New kitchens, some new baths, flooring, a new roof and a new sewer.

Do refrigerator, range, faucets, toilets, kitchen, flooring, bathrooms, rough plumbing, siding, roof, HVAC, fencing, rough electrical, hardscape.

It is a mixed use property (storefront 1st floor, 2 additional floors of apartments above).

Multiple improvements done on this duplex in 2021, including new roof, gutters, flooring, drywall, electrical, appliances, and heating/cooling unit for the second floor.

While this is a significant sum, trashing a unit by damaging the paint and flooring can easily result in expenses over $10k plus the lost rent, court and attorney costs. 

I painted it, redid the floors, put on new doors and hardware, fixed all the existing issues (leaks in roof, toilets not working, sinks leaking, water damage on exterior and upgraded the panel to a 220V) What was the outcome?