Deductions & credits

I have gotten different answers on this... I ended up reporting it on Sched C.  But, after a subsequent conversation, it seems better (next time) to use Inventory and Cost of Goods Sold for rehabs.  After all, that is what it is, I think.  Yet, I do not understand the tax treatment of such.  I have not thought of including it as an Investment, as you say, but that now sounds better !  What is the tax treatment of the Inventory vs. Investment treatment?  It seems there are many ways to handle these !  THANK YOU !