We just tried to do this on a house and then realized that Corpus is very unfriendly to Airbnb unless you have a commercially zoned unit or you're Airbnbing an accessory dwelling.

Some others that I've used/am considering/had recommended to me:On-site, coin-operated laundry machines (most relevant for multi-family properties)Renting out storage space in basement or on-site shedRenting out unused off-street parking (where I live, winter RV parking is at a premium)Converting non-conforming to conforming rooms (including basements) to allow for re-organization and classification as bedroomsAdding accessory dwelling unit(s) to your property (may not even require separating lots)Separating utility metering (or installing individual unit readers) on multi-unit properties that are currently metered togetherDepending on your market, furnishing a portion of your units and renting them out fully furnished to shorter-term renters*Some (most) of these will depend on how individual properties are zoned, what zoning requirements are in your locale, and what there is demand for in your market.

If you are an owner occupant, build and ADDU and then move from the property the ADDU reverts to an "Accessory Structure," and if rented as a residence will be considered "non-conforming" by the city, and may be subject to code compliance issues a s potentially legal action.

I would budget more than $1,500 for the furnace unless you're going to do the labor yourself they start at 1200 and go up to well over 3,000 depending on the size of the property the cheapest plumber ever quoted me was $1,000 labor and then there was another 200 hundred dollars worth of accessories once you start connecting the vents.

An adult and child day care center as an accessory use when located within a school or religious facility building.

Reply from City of Columbus:In almost all cases at this time, a second dwelling (also known as an Accessory or Auxiliary Dwelling Unit (ADU)) unit would require a zoning use variance prior to permitting and construction and must meet the development standards as shown on the attached as for any other dwelling unit unless granted a variance as part of the use variance, also known as a Council Variance.The Columbus Zoning Code which contains all the requested standards is online at https://www.municode.com/library/#!

However, please note buying homes with accessory dwelling units (ADUs) may cost more in LA.

Seems to come up a lot with “accessory” items.

Yes new vanity, paint, accessories (towel rack, mirror, toilet seat if needed, etc) will give you the biggest bang for the buck.

Also, the AB68 language says, "If there is an existing primary dwelling, the total floor area of an attached accessory dwelling unit shall not exceed 50 percent of the existing primary dwelling".