Can someone help me to understand small development loans?

Hi, I am hoping somebody can give me a bit more info on what options I may have in regards to a small development loan.  Essentially I am hoping to build two houses on a subdivided block of land (i will subdivide etc).  I would like to live in one of the houses and sell off the other.  I have heard about Gross Realisable Value (GRV) loans where the interest may be capitalized until you sell the property.  Do these loans have the same servicing requirements as a standard loan?  Eg, according to the Commonwealth Banks normal servicing constraints I may be eligable to borrow upto 400k with my current commitments.  I will have 400k of my own money, hence meaning the most my project could cost is 800k.  However, I am estimating the cost would equate to approximately 1 million, meaning that I would be short 200k?

I estimate I should be able to sell the second house for a minimum of 600k, leaving me with little or no mortgage.  So, i suppose my main question is do the development loans not worry so much about standard servicing requirements?  And, if so can someone tell me more?

Any info would be greatly appreciated.

Thanks