. $40,732 mins expenses..At a PP of $1.25M with 30% down ($375k) you'll be short of a 10% COC return..Also 7.2% seems like a very strong rate on a 10plex.

My question is while I was looking on redfin, I found a big 14-unit buildings that is for sale around $3 Million.

The main thing you will need to do before renovating any house or building is to make sure you have a good team in place (an administrator or a licensed care home manager).

You don't want to rush to partner just to get your next property.If I was new again now and didn't have the capital to get my second one, I would go to every meetup in my area, meet other investors, and build relationships.

Build the relationship with them.

What are the pros and cons of building from scratch for the purpose of STR?

So I would like your advice.My idea:My sister and I would build a fourplex together and finance it as owner occupied.

They don't buy a lot, and even when they or any affordable housing developer buy land, it often can take forever for them to consider the property and then the actual escrow can be long if they are building the capital stack to buy the property. 

Determine what your financial expectations are for an investment property, run your numbers very conservatively (and for gosh sake, include room for unexpected costs, even on a new build) and then see if it makes sense.

Building the right team of strategic partners is key to effectively completing development/new construction projects.