For a "dwelling unit" to be considered residential (27.5 year depreciation), it cannot be used on a 'transient basis' see Tax code - 26 U.S.

If you have a valid lease in place (and in your scenario, I would never do a formal lease/rental agreement...you should treat this like an extended stay hotel, which doesn't give the tenant an equitable interest), you should follow Sec. 92 of the Texas Property Code.

Hey Everyone,I have a single-family house in Folsom 95630 zip code area.

The house next to ours has a septic tank, so I'm wondering if the code has changed since that one was built in 2001.

Once the drywall was out, the insulation has to be brought to code.

https://www.courier-journal.co...

And yes, the lease expressly states no improvements or alterations can be made to the property without written consent of the landlord. 

Across the Greater Philadelphia market area, half of ZIP codes recorded a High or Moderate level of demand and roughly one-third were in the Slow or Limited category.The hotest part of the city is NE Philly. 

Check the zip code of the property you're interested in on zillow, redfin, etc. and you can see how much similar units are renting for in the area and I shoot for the most conservative amount of income when doing my analysis.

What zip code did you find this property in, and how many beds/baths does it have?