Materials have increased more than 20% in the last 5-8 years.

And does the person doing the labor get paid or only the materials paid for by the partnership?

all materials, all labor costs to others, Not you, utilities, interest payments, permits, licenses, auto/truck expenses, tools needed are all deductable. 

--reach out and thank them upon getting the booking and ask if they have any questions--send a "Welcome" email or automated message during the week prior to arrival--reach out the day after arrival to ask how everything was the first night and ask if there is anything that the property needs--reach out at the end of the stay (that morning or within 24 hours) and ask how everything was, anything to improve, anything to add to the house and then offer an incentive for returning guests.My 2 cents,Mike Absolutely stay in your place as Mike said.You will see things the cleaners will never let you know about.We stayed in our PF will putting up the Christmas decorations and found a cracked plastic shelf in the fridge. 

We have had two homes broken into and materials stolen recently.

How are they sourcing materials?  

Estimated CostsADU costs can range DRAMATICALLY depending on the state of the lot, custom vs fast track plans, size of ADU, materials and finishes, speed and quality of the builder, etc.

Btw, I’ve found that these types transactions actually work better when used to purchase/sell COMMERCIAL property. 2.

Price out as much as you can in terms of materials and estimates.