My idea was I could live there immediately and also do all the minor work that would not require an actual tradesmen, which would allow me to start building equity.

I built a house and it’s going to be difficult to sell as I have no equity in it because of Cost to build.

If your IRA receives an equity portion of profits from the business, it will likely have tax liability via UBIT that would be detrimental.Owning income producing real estate or interest from lending are passive activities not subject to UBIT. 

If OP can lever-up while maintaining adequate reserves, he will be in better position than buying with heavy cash position.  

In areas with rapid and sustained appreciation, you can use the equity gained through appreciation to purchase additional properties.

Structuring a joint venture (JV) or equity partnership can make the deal appealing by offering a share of cash flow and appreciation. 

You have to be willing to sell your properties and access the equity to buy up. 

What the concept you mentioned is talking about is leveraging equity to gain cash vs. selling essentially. 

You didn't write how much 'sweat equity' you put into this place, but it was likely well worth it given the $400K cash out.  

It’s a strategy that allows investors to acquire rental properties with little to no money out of pocket while building equity along the way.If you're considering using the BRRRR method to grow your real estate portfolio, here's everything you need to know about how it works, its benefits, and potential risks.What is the BRRRR Strategy?