I own a SFR in Dallas which is valued at around $460k. I'm currently just shy of breaking even on rent.
A major plus to this property is the zoning to add another unit in the backyard .

It would be about 900 SF and would bring in an additional $2500 per month. All estimates show construction costs to be $170-210 per square foot . It should be $200k total . Adding permits and design plans adds another $22k.

I can tap into my business line of credit for about $80k and some savings at $40k to fund this project. To be on the safe side, I will need around $120k .

I just came across this article at" 0% interest financing through business credit lines" . It just seems to be TOO good to be true.

Would appreciate some feedback or opinion on this .

Here's the Article:

What is business credit stacking?

I'm not sure how they will check your personal credit but not report balance and payment history. I'd really deep dive on this.

How would making immediate payments help you on a long term payback? You would not receive rent until the project is complete and move in ready. 9 months? 12? You have to start making minimum payments in 30-45 days.

At some point the free runs out. Then you are churning cards to keep the benefits of the cards. How much time will that require?

If you have enough equity in your current residence then a HELOC would be cleaner. Frost Bank just closed a loan at no closing costs and interest only on what you draw as needed. It was 8% but a much simpler loan. One loan for as long as you need the financing.

If your deal doesn't pencil at a rate like that long term you might consider not doing it. At some point the credit card charges will be higher than 8.