As I don't have large down payment, I am thinking to start building a portfolio with finding off market deals that have equity and do bit rehab/renovate and later get refinanace to pay off HML with a traditional lender/DSCR loan. please share any thoughts on my plan and any lending resources.

We welcome any suggestions or insights you may have Additionally, if anyone has information on the approximate cost of building a duplex and triplex in California, we would greatly appreciate your input.To provide context, neighboring properties in our area offer insights into the local housing market.

BiggerPockets has a section just for this, Under the BUILD YOUR TEAM tab- then select- MEET UPhttps://www.biggerpockets.com/forums/521This will help you see the opportunities in your own back yard and here from your LOCAL experts. 

If so, is the is the same rate with houses or buildings? 

Investment Info:Mixed-use building Purchase price: $405,000 Cash invested: $20,250Mixed use investment. 2 residential units with 1 storefrontWhat made you interested in investing in this type of deal?

I have been reading many books (and posts in this forum) and trying to build a system for investing. 

Option B allows you to save an extra $12,000 s month (minus maintenance costs) and build equity.

Every market is different so you need to niche down into the neighborhoods to get accurate numbers.

Go to BUILD YOUR TEAM at the top of your screen, and you can search for other MEMBERS or LOCAL MEETUPS.

Mortgage Interest Deduction: You can deduct the interest paid on a mortgage used to buy, build, or improve your home.4.