How to Finance a Triplex when planning to make it a Quadplex

[Jacob Eddy]

We recently went under contract on a Triplex for $380K and can get a conventional mortgage for a rate of 5% with a 25% down payment of $95K.  The property has a shell that can easily be finished out, making it a Quadplex, and would cost an additional $70K to add the 4th unit.  We can pay cash to have the 4th unit finished, then refinance the property to pull some of the money back out, but wanting to know if anyone would recommend another strategy instead?  This is our first decent size deal as investors and extremely new to thinking outside the box for financing any other way than a conventional mortgage.  Any advice is much appreciated!  Thank you!