I know with a hard money lender, you lost good amount of profit. 

Seriously, it's important.And as mentioned above, the amount of rent you receive on multi-family properties is based on 12 month rental comps.  

With the current mortgage rate constraints affecting how many buyers are willing to enter the market we are seeing a lot of borrowers have success with the BRRRR strategy with plans to sell in the next 3-5 years when interest rates go down.Researching potential LTR and STR rental amounts and seeing if holding for a few years is a viable option is a good analysis to do well. 

Hi @Zhong Zhang I have used vacancy hacks over the years to get personal properties under 1% when turning tenants over. 3% increase depends on renewing or getting new tenants, when renewing tenants that's  a safe amount. 

3) Windows - a fair amount of windows took damage.

Just to name a few: Borrower's Experience FICO Loan Amount Loan Type being sought: Perm (30 yr ams), Bridge (12-36mo I/O), Rehab (12-36mo I/O), Ground Up (12-60mo I/O) Property Type (1-4 unit, 5+ MF, Warehouse/industrial, Hospitality etc)If you have a specific deal in mind, then you can have a lender (or broker) look at it and give you a better idea.

Local PM's can get you the most accurate rent amount for your property.

Either way it would be a grey area, selling a house with a different amount of units/bedroom/bathroom seems extreme though. its an auction site, I have seen auction sites miss the fact there was additional lots in a sale.

The loan amount is 150k let's say. 

The cost to build will be significantly more than the amount of “value add” of an ADU putting you in a negative equity position.