Flipping houses for profit. How to categorize expenses?

I began a business of buying and selling houses for profit or use in rental income. I only have purchased one so far and need to know how to classify my expenses. For example the costs of appliances, fixtures, tile, paint, trim, plumbing all work that I did myself to install, are these able to be deducted as supplies or added to the cost basis? It would seem like some expenses must be supplies but where to draw the line? I haven't sold the house yet so I have no income to claim. The only expense I paid a subcontractor for is siding and window installation. I assume that would be added to the cost basis.