And there must be one in the basement too.Other things I failed in the past:1)Water heater pressure relief valve must have a metal pipe going to about 3-4 inches from the floor (plastic not acceptable).

Some tenants are like children and pets where they try to take an inch so that eventually they get away with taking a mile; unfortunately for you, you are now seeing this firsthand.

Carefully have someone raise or tilt the washer an inch or so to give you some room under it, feel around the floor directly under.

See what you have , if there is a difference of over 1 to 2 inches , there are other problems 

Make sure the siding is at least 8 inches above grade, ensure that there is no untreated wood in contact with soil or foundation, check any exposed studs for damage, check any exterior trim/sills that come close to the ground, etc.Also, certain areas of the country are more termite prone than others.

Even though it will suck now at 25, when your 35...45...55...65...75 you will look back on these days and truly say “oh those were the good days when I struggled for every inch”.

They do tend to have a bit of a smell (like if your nose is within 6 inches of the tank), but nothing that would stay behind after your prospective tenants move out.  

Specifics for this building:This is a long term hold.Looking for balance of soundproofing and lower long term costApartments are one 1br and 3 studioLocated in lower income area so tenants will be hard on flooring and will have a higher turnover rateCurrent upstairs floor is 2 inch hardwood planks attached directly to joists.Ceiling below is 12ft high finished with a combination of plaster/drywall Wondering if anyone has had something similar and what worked for them?  

A normal rain doesn't pose a problem, but the buckets mother nature dumped on our area last week -- about 4-5 inches in total -- and you can see how this might be a problem.

The City says that the lots have to be built up 18 inches above the center line of the Street to build.