Even if you haven't been in this kind of setup before, I am curious to hear your opinion. 

Consider connecting with local REI meetups, hospitality groups, or even online forums like this one to find like-minded investors.You could also pitch your successful track record to potential equity partners.

This is pretty clean.Scenario 2:  Your partner has owned the house for 15 years and has been taking accelerated depreciation, so the book value of the house is very low. 

In this space it's all about building a portfolio, my 1 house clients are at the highest risk because they can only rely on that 1 property, they don't have others to help alleviate the burden.

Hi Ursula,Even though this post is a few months old, I thought I’d chime in just in case you’re still working through this or for future projects.

I have spreadsheets filled with material lists for every phase of the build that includes pricing for materials as well as labor, and sources that I use for them.

This is an absolute no brainer. 

Please share as I explore using them for my rentals.

You're taking a great first step by joining this group and seeking guidance.

Some lenders offer creative solutions, like a cross-collateralized loan, where they use your existing equity as security without refinancing the duplex.Another idea is partnering with private lenders or exploring a second-position mortgage, depending on your lender's terms.