With the new tax laws that have changed, I see that you can not write off interest paid on a HELOC on your "primary residence" unless it’s used for the repair, improvement or purchase of property.

My only point is unless you can see the future all you are left with is making choices that improve your percentage chance of success. 

Acquiring below market and implementing a value-add improvement plan will result in a portfolio of properties that appreciate over time and that also offer significant tax advantagesPick the right market – not all housing markets were impacted in the same way during the last recession.

The important thing to point out is that like you said, this job made it a full bath, which is an improvement/addition, not a repair.

My Business partner wants to move in and we can improve it while we house hack it.

Do investors commonly make capital improvements to boost the amount they are eligible to borrow against?

Also recently went alcohol-free, so have an abundance of time and energy to spend building value and wealth through RE!

I have seen up to a 100 point score improvement on some files.

So my thoughts were to build a plot, build an energy efficient townhouse, each floor will be rented by a different family.  

It seems like a lot to someone who is trying to save that on their own from their day job to improve their position, but in all reality, you can make a great ROI on that money in real estate if placed correctly.