Electrical/plumbing/shower cement board & vapor barrier.....

If you are I would consider putting down a vapor barrier first, along with a sub floor like Dricore or some other dimple board to keep the flooring directly off the concrete.  

And most garages are not built as living space.It starts with the slab - 1) Different PSI concrete, 2) Wrong steel, 3) No (or wrong) vapor barrier 4) No hold-downs, 5) No shear walls....and it goes on from there.

Inventory is very low and properties vaporize! 

You'll want to have sub-slab sampling of the soil gas to see if there is a potential for vapor intrusion as well as groundwater.  

You should always have P100 filters and organic vapor cartridges standing by.

Then replace the vapor barrier.Why cheaper then new drains.

High turnover, lengthy vacancy periods, and greater tenant damage will vaporize your hoped-for profit.

Site-built homes have numerous areas in which to place utilities, and they usually don’t close the only escape route for occupants, as happens many times in mobile homes.”In addition, pre-1976 mobile homes had less insulation in walls, ceilings and floors, uninsulated air ducts and no vapor barriers in their roof cavities, making them an increased risk of fire hazards.

No smoking, to include cigarettes, pipes, cigars, or any other tobacco smoking material, and/or vapor like products is allowed within the structure of the building; including the rental unit, basement, garage, or outside on the adjoining grounds, either by the Tenants or their guests.